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Title:
UV RADIATION CLEAVABLE COMPOUNDS
Kind Code:
A1
Abstract:
The present invention relates to a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant and/or UV absorbing and/or photostabilizing properties.


Inventors:
EGGLESTON, Ian (6 Avondale Buildings, Bath BA1 6RD, GB)
POURZAND, Shararah (31 Calton Gardens, Bath BA24QG, GB)
Application Number:
GB2013/052401
Publication Date:
03/20/2014
Filing Date:
09/13/2013
Assignee:
UNIVERSITY OF BATH (Claverton Down, Bath BA2 7AY, GB)
International Classes:
C07D213/81; A61K31/513; A61P35/00; C07D309/40; C07D401/12; C07D405/12
View Patent Images:
Domestic Patent References:
WO2009088975A2N/A2009-07-16
Foreign References:
201000359322010-02-11
63796552002-04-30
201102755582011-11-10
Other References:
SIMPSON C J ET AL: "Preparation of vinylphenols from 2- and 4-hydroxybenzaldehydes", TETRAHEDRON LETTERS, PERGAMON, GB, vol. 46, no. 40, 3 October 2005 (2005-10-03), pages 6893-6896, XP027863751, ISSN: 0040-4039 [retrieved on 2005-10-03]
CH. SOUMYANANDA: "Curcumin recognizes a unique binding site of tubulin", MEDICINAL CHEMISTRY, vol. 54, 2011, pages 6183-6196, XP002715584,
Attorney, Agent or Firm:
MCCONCHIE, Connor (D Young & Co LLP, 120 Holborn, London EC1N 2DY, GB)
Claims:
CLAIMS

1. A compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant and/or UV absorbing and/or photostabilizing properties. 2. A compound according to claim 1 , wherein the compound is of Formula I

C-M Formula I wherein C is a precursor to a transition metal chelating compound;

M is an optionally substituted cyclic moiety having x number of rings wherein x is an integer from 1 to 3 and wherein M is at least substituted by OH or NHF , wherein R1 is H or hydrocarbyl; and the connection between C and M is photolabile when exposed to electromagnetic radiation having a wavelength in the range of 320 to 400 nm so as to yield a first compound which is a transition metal chelating compound and a second compound which is a cyclic compound having x+1 rings. 3. A compound according to claim 2, wherein is at least substituted by OH or NHR-i, wherein is H or C Cs alkyl.

4. A compound according to claim 3, wherein M is at least substituted by NHFM , wherein R-i is a C C6 alkyl.

5. A compound according to claim 3, wherein M is at least substituted by OH. 6. A compound according to any one of claims 2 to 5, wherein the or each ring of M is a 5 to 10 membered carbocyclic ring, which may optionally include one or more hetero atoms.

7. A compound according to claim 6, wherein the or each ring of M is a 6 membered carbocyclic ring, which may optionally include one or more hetero atoms.

8. A compound according to claim 7, wherein M includes at least one hetero atom. 9. A compound according to claim 8, wherein the or each ring of M is additionally substituted by at least one substituent selected from the group consisting of H, OH, hydrocarbyl, oxyhydrocarbyl, nitro, halo, haloalkyl, nitrile and amino.

10. A compound according to claim 9, wherein two or more of the additional substituents combine to form a further ring comprising at least one hetero atom. A compound according to any one of claims 2 to 10, wherein x is 1 or 2. A compound according to claim 1 1 , wherein M is of Formula He:

wherein D is a ring comprising from 3 to 10 members, R3 is H or C Ce alkyl, R4 is OH or NHRi wherein R-i is H or C C6 alkyl, R2 is a substituent independently selected from the group consisting of H, OH, hydrocarbyl, oxyhydrocarbyl, halo, haloalkyi, (CH2)i-ioOH, nitro, nitrile and NR 0Rn, wherein R10 and Rn are independently selected from H and C C6 alkyl, wherein each R2 may join together to form a ring optionally containing at least one heteroatom, m is an integer from 0 to 8, R9 is H or C Ci0 alkyl and wherein denotes the point of attachment with C.

13. A compound according to claim 12, wherein R3 is H or methyl, R4 is OH or NH2, and R2 is a substituent independently selected from H, hydroxy], C-,-C6 alkoxy, Ct-C6 haloalkyi, NRnR-12 wherein Rn and R 2 are independently selected from H and C C6 alkyl, and R9 is H or C C10 alkyl. 14. A compound according to any one of claims 2 to 13, wherein C is a precursor to an iron chelating compound.

15. A compound according to claim 14, wherein C is of Formula Ila:

wherein B is an optionally substituted 5 to 10 membered carbon ring which may contain one or more hetero atoms, Ri3 is H or a hydrocarbyl group, Ri is H or C-rCe alkyl, and wherein - — denotes the point of attachment with M.

16. A compound according to claim 15, wherein B is an optionally substituted phenyl ring.

17. A compound according to claim 15, wherein B is an optionally substituted pyridine ring. 8. A compound according to any one of claims 15 to 17, wherein R-|3 is a cyclic group.

19. A compound according to claim 18, wherein Ri3 is an aryl group or a heteroaryl group.

20. A compound according to claim 19, wherein R13 is pyridyl.

21. A compound according to any one of claims 15 to 20, wherein R13 is pyridyl and R 4 is H.

22. A compound according to any one of claims 15 to 21 , wherein ring B is substituted with a group (CH)nOH, wherein n is an integer from 0 to 10.

23. A compound according to claim 2, wherein the compound is of formula Ilia

Formula Ilia wherein B, D and R2 , R3, R4, Rg, R-i3 and R-μ are as defined above.

24. A compound according to any one of claims 2 to 23, wherein C is a precursor to an iron chelating compound selected from isonicotinoyl hydrazone, pyridoxal isonicotinoyl hydrazine, 3-hydroxy-1 ,2-dimethyl-4(1 H)-pyridinone or 3-[3,5-Bis(2-hydroxyphenyl)-1 H- 1 ,2,3-triazol-1-yl]benzoic acid. 25. A compounds according to claim 1 selected from:

26. A compound for use in medicine, wherein the compound is as defined in any one of the preceding claims.

27. A compound for use in the prevention of a condition or disease associated with exposure to uitraviolet-A (UVA) radiation, wherein the compound is as defined in any one of the preceding claims.

28. A compound for the use of claim 26 wherein the condition or disease is selected from skin cancer, such as malignant melanoma, wherein the compound is as defined in any one of the preceding claims.

29. A composition comprising the compound defined in any one of claims 1 to 25, and one or more dermatologically acceptable carriers.

30. A cosmetic composition comprising the compound defined in any one of claims 1 to 25, and one or more dermatologically acceptable carriers.

31. A compound, composition or use as defined herein with reference to the examples.

Description:
UV RADIATION CLEAVABLE COMPOUNDS

The present invention relates to a compound which is useful in sun screen formulations. The present invention also relates to formulations comprising the compound and the use of the compound in medicine for the prevention of diseases or conditions associated with exposure to sunlight.

BACKGROUND TO THE INVENTION

Exposure of human skin to sunlight is known to produce a number of effects. Although some of the effects are perceived by some to be positive e.g. tanning, many of the effects have a negative impact on health. In particular, exposure of human skin cells to UV radiation from the sun is considered to be one of the main factors in the development of photodermatoses, cutaneous photoaging, immunosuppression and skin cancers. As a result, the ability to protect human skin cells from the harmful effects of sunlight is very important.

Sunlight is polychromatic, i.e. it is composed of electromagnetic radiation of different wavelengths. In particular, the sunlight striking the Earth's atmosphere can be considered to be composed of electromagnetic radiation with wavelengths spanning five regions: ultraviolet C (UVC), ultraviolet B (UVB), ultraviolet A (UVA), visible light and infrared.

The damaging effects of sunlight are derived mainly from the UV portion. For example, skin cancer resulting from exposure to UV radiation from the sun is a particularly concerning issue. The global incidence of skin cancer is thought to be increasing year by year and approximately half of all cancers in the US are skin cancers. Prolonged sun exposure is the major cause of melanoma and non-melanoma skin cancer (NMSC).

Owing to their differing wavelengths, UVA, UVB and UVC do not all have the same effect on human skin; UVA is considered to have a wavelength spanning 320 to 400nm, UVB is considered to have a wavelength spanning 290 to 320 nm and UVC is considered to have a wavelength spanning 230 to 290 nm.

Historically, it had been thought that UVB exposure was most damaging to human skin. This is because DNA absorbs UVB radiation. This absorption can lead to damage of the DNA structure. For example, it is possible that upon absorbing one photon of UVB radiation, two neighbouring bases on the DNA backbone will dimerise. This change in structure leads to corresponding errors when the DNA is later replicated and thus can lead to cancerous growths. This type of damage is sometimes referred to as direct damage, as the UVB acts directly on DNA. Conventional sunscreens provide protection through organic molecules or inorganic materials that filter out harmful UV radiation, thereby limiting the dose at the skin surface. Typically though, such sunscreens provide greater protection against short wavelength UVB than UVA, and more than one active sunscreen component is required to provide broad spectrum protection. This is because unlike UVB, the UVA component of sunlight is oxidative in nature and generates reactive oxygen species (ROS) in cells via photochemical interaction with intracellular chromophores. So while the shorter UVB component of sunlight directly interact with DNA causing DNA damage and mutations mainly in the epidermal layer of the skin, the longer UVA component of sunlight penetrates to the deeper layers of the skin and causes damage to DNA, lipids and proteins via the production of ROS. It is noteworthy that, although short-lived, ROS are present even after UVA exposure has been stopped, because they are also generated by additional non-photosensitized mechanisms such as NADPH oxidase, which generates superoxide radicals. Furthermore, there is now strong evidence that exposure to UVA doses at natural exposure levels leads to an immediate release of potentially harmful "labile" iron in skin cells. It is this dual role of UVA as a generator of ROS and an enhancer of labile iron that classifies this radiation as a potent oxidising component of sunlight. UVA-mediated generation of ROS not only induces direct oxidative damage to skin constituents, but the immediate increase in the cytosolic labile iron pool (LIP) that it causes both intensifies the oxidative damage already occurring in the skin cells, and may also exacerbate skin damage caused by further UVA exposure.

As the cumulative negative effects of UVA are not being adequately addressed by current sun screen formulations, improved ways of protecting the skin from the harmful effects of sunlight, in particular UVA radiation, are desirable. One approach to develop better sunscreen products is the addition of antioxidant compounds to augment photoprotection. Thus there may be two layers of protection in such compositions wherein i) UV filters provide 'passive' protection by absorbing and reflecting harmful UV rays from the skin and ii) antioxidants offer 'active' protection by boosting the body's natural antioxidant reserve to quench any ROS generated from UVA that has passed the UV filters. Despite the attractive nature of this photoprotection strategy, conventional antioxidants which scavenge ROS, such as vitamin C (ascorbic acid) and vitamin E

(tocopherol) have only a very modest protective effect, as such sunscreen ingredients cannot properly address the phenomenon of UVA-induced excess labile iron release in cells that can still contribute to the generation of ROS and oxidative damage. Conventional radical scavengers can therefore not neutralise the overall ROS production upon exposure of cells to strong oxidising agents such as UVA which also promote redox-active labile iron release in cells.

Although the use of iron chelators for photoprotection was proposed almost 20 years ago there has been little development of topical specific iron chelators for photoprotective purposes. This is probably because most strong iron chelators are likely to affect iron homeostasis in healthy cells. Such agents are capable of starving cells of the essential nutrient iron that is required for the function of important iron-containing enzymes involved in various cellular functions, notably division. Some chelators such as desferrioxamine (DFO) are also specific inhibitors of ribonucleotide reductase enzyme (RR) that requires iron incorporation into its R2 subunit to promote DNA synthesis. The present invention seeks to address some of the problems associated with the compounds and formulations of the prior art.

In particular, the present invention seeks to address the limitations of existing sunscreens through the design of a single sunscreen component that provides a dual mode of protection, not only protecting against the effects of labile iron with an iron trapping agent (i.e. iron chelator), but also generating a scavenger of harmful ROS (i.e. antioxidant).

Importantly, both these protective effects are triggered upon demand, to provide protection when and where required, and to the appropriate extent i.e. providing greater protection to more exposed areas of skin, and increased UVA blocking as the radiation dose increases. SUMMARY OF THE INVENTION

In its broadest aspect, the present invention relates a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant and/or UV absorbing and/or photostabilizing properties. In one aspect, the present invention relates to a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant properties.

In one aspect of the present invention, there is provided a compound of Formula I

C-M Formula I wherein C is a precursor to a transition metal chelating compound; wherein M is an optionally substituted cyclic moiety having x number of rings, wherein x is an integer from 1 to 3 and wherein is at least substituted by OH or NHR-i , wherein is H or hydrocarbyl; and wherein the connection between C and M is photolabile when exposed to ultraviolet-A (UVA) radiation so as to yield a transition metal chelating compound and a cyclic compound having x+1 rings.

In a further aspect of the present invention, there is provided a compound as defined herein for use in medicine.

In a further aspect of the present invention, there is provided a compound as defined herein for use in the prevention of a condition or disease associated with exposure to ultraviolet-A (UVA) radiation.

In a further aspect of the present invention, there is provided a composition comprising a compound as defined herein, and a dermatologically acceptable carrier.

For ease of reference, these and further aspects of the present invention are now discussed under appropriate section headings. However, the teachings under each section are not necessarily limited to each particular section.

DETAILED DESCRIPTION

In one aspect, the present invention relates to compound which when exposed to ultraviolet- A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant and/or UV absorbing and/or photostabilizing properties.

In one aspect, the present invention relates to a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is a transition metal chelating compound and a second compound which has antioxidant properties. In one aspect, the present invention relates to a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is an iron chelating compound and a second compound which has antioxidant properties.

In one aspect, the present invention relates to a compound which when exposed to ultraviolet-A (UVA) radiation is cleaved to produce a first compound which is an iron chelating compound and a second compound which is a coumarin or iminocoumarin compound which has antioxidant properties. In one embodiment, the compound is a compound of Formula I

C-M Formula I wherein C is a precursor to a transition metal chelating compound;

M is an optionally substituted cyclic moiety having x number of rings, wherein x is an integer from 1 to 3 and wherein M is at least substituted by OH or NHR-i , wherein P is H or hydrocarbyl; and wherein the connection between C and M is photolabile when exposed to ultraviolet-A (UVA) radiation so as to yield a first compound which is a transition metal chelating compound and a second compound which is a cyclic compound having x+1 rings. Transition metal chelating compound

A "transition metal chelating compound" as used herein is a compound which is capable of effectively chelating a transition metal.

The chelation of a transition metal can be measured according to methods known in the art. For example, with regard to iron chelation, it is known that Fe3+ quenches the fluorescent dye calcein. Accordingly, the ability of a compound to effectively chelate iron can be determined by measuring the change in calcein fluorescence in the presence of iron. One such -method is disclosed in Pelle et al, Photodermatology, Photoimmunology &

Photomedicine, 27, 231-235, 2011. An effective or strong iron chelator is a compound that avidly binds iron, selectively forming a stable complex with ferric ion (Fe3+), and depleting the cellular concentration of free Fe3+. The efficiency of chelation of Fe3+ may be expressed in terms of -log10[Fe3+], or pFe3+, the concentration of free, unchelated Fe3+ in the presence of the chelator. For example, strong iron chelators pyridoxal isonicotinoyl hydrazone (PIH) and salicaldehyde isonicotinoyl hydrazone (SIH) have pFe3+ values of 28 and 29, respectively.

salicaldehyde isonicotinoyl hydrazone (SIH) pyridoxal isonicotinoyl hydrazone (PIH) Iron chelators such as HBSer with pFe3+ = 20 are considered to be "weak" and do not chelate sufficient intracellular Fe3+ to provide a protective effect upon UVA-induced iron release.

In one embodiment, the transition metal chelating compound is an iron chelating compound. In one embodiment, the transition metal chelating compound has a pFe + of 23 or greater.

Further, a "precursor" to a transition metal chelating compound is a compound which is not capable of chelating a transition metal to any significant extent. Thus, as used herein a precursor to a transition metal chelating compound is a compound which is not capable of effectively depleting the basal cellular concentration of a transition metal ion.

In one embodiment, the precursor to a transition metal chelating compound is a precursor to an iron chelating compound. In one embodiment, the precursor to an iron chelating compound has a pFe3+ of 20 or less.

The precursor may be substantially identical to the resulting transition metal chelating compound with the exception that one or more of the chelating groups on the transitional metal chelating compounds is blocked. In the context of the present invention, C can be considered to be a precursor to a transition metal chelating compound where M is used to block chelating group(s) of C. Blocking may be achieved by M being directly bound to the chelating group and/or by moiety M sterically hindering the chelation of the transition metal.

Preferably, is bound directly to the chelating group being blocked.

In view of the ability of M to block the chelating groups of the transition metal chelating compound, it can be said that the transition metal chelating compound is "caged" and that M is acting as a "caging group". Therefore, any reference in the present application to a caged compound or group is a reference to C, any reference to a "caging" group or compound is a reference to group M and any reference to "uncaging" refers to M being cleaved from C.

Antioxidant

An "antioxidant" or a compound which has "antioxidant" properties refers to a compound which is able to inhibit the oxidation of other molecules. In particular, such compounds are able to prevent the oxidation of other molecules by scavenging free radicals which would otherwise be able to initiate a negative cellular chain reaction. A typical example of an antioxidant is ascorbic acid.

UV absorbing

The term "UV absorbing" as used herein refers to a compound which is capable of absorbing the energy associated with a photon of UV radiation and convert said energy to a less harmful form, such as heat. For example, melanin is a pigment which is able to absorb UV radiation and, via a process known as internal conversion, transition from the excited state following photon absorption to a lower energy state without the subsequent emission of a photon. Commercially available UV absorbers include butyl methoxydibenzoylmethane (BMDBM) and octyl methoxycinnamate (O C).

Photostabilizing

One possible result of a compound absorbing a photon of UV radiation is the transition of that compound into an excited triplet state. Such triplet state species are able to stimulate the production of reactive oxygen species (ROS). As described above, the production of ROS can be a factor in cellular damage. The term "photostabilizing" as used herein refers to a compound which is capable of quenching compounds which persist in a triplet state and therefore which are able to prevent the production of ROS. Examples of photostabilizing compounds include 3,3-diphenylacrylate derivatives such as e.g. octocryiene (PARSOL® 340) or Polyester-8 (Polycrylene®). Photolabile

The term "photolabile" refers to a bond which, following exposure to electromagnetic radiation, absorbs one or more photons and undergoes electronic excitation which results in either direct cleavage of said bond or some other form of chemical transition, e.g. isomerisation, so that one or more other chemical bonds within the molecule are inevitably cleaved.

Hydrocarbyl and oxyhydrocarbyl

The term "hydrocarbyl group" as used herein means a group comprising at least C and H and may optionally comprise one or more other suitable substituents. Examples of such substituents may include halo, alkoxy, nitro, an alkyl group, a cyclic group etc. In addition to the possibility of the substituents being a cyclic group, a combination of substituents may form a cyclic group. If the hydrocarbyl group comprises more than one C then those carbons need not necessarily be linked to each other. For example, at least two of the carbons may be linked via a suitable element or group. Thus, the hydrocarbyl group may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for instance, sulphur, nitrogen and oxygen. A non-limiting example of a hydrocarbyl group is an acyl group. A typical hydrocarbyl group is a hydrocarbon group. Here the term "hydrocarbon" means any one of an alkyl group, an alkenyl group, an alkynyl group, which groups may be linear, branched or cyclic, or an aryl group. The term hydrocarbon also includes those groups but wherein they have been optionally substituted. If the hydrocarbon is a branched structure having substituent(s) thereon, then the substitution may be on either the hydrocarbon backbone or on the branch; alternatively the substitutions may be on the hydrocarbon backbone and on the branch.

In some aspects of the present invention, one or more hydrocarbyl groups is independently selected from optionally substituted alkyl group, optionally substituted haloalkyl group, aryl group, alkylaryl group, alkylarylalkyl group, and an alkene group. In some aspects of the present invention, one or more hydrocarbyl groups is independently selected from C CiD alkyl group, such as Ci-C6 alkyl group, and C C3 alkyl group. Typical alkyl groups include alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, and C8 alkyl.

In some aspects of the present invention, one or more hydrocarbyl groups is independently selected from aryl groups, alkylaryl groups, alkylarylalkyl groups, -(CH2)Mo-aryl, -(CH2)i_i0- Ph, (CH2)1-10-Ph-C1-10 alkyl, -(CH2)1-5-Ph, (CH2)1-5-Ph-C1-5 alkyl, -(CH^-Ph, (CH2)1-3-Ph-C1-3 alkyl, -CH2-Ph, and -CH2-Ph-C(CH3)3. The aryl groups may contain a hetero atom. Thus, the aryl group or one or more of the aryl groups may be carbocyclic or heterocyclic. Typical hetero atoms include O, N and S, in particular N. In some aspects of the present invention, one or more hydrocarbyl groups is independently selected from -(CH2)-,.10-cycloalkyl, -(CH2)i-10-C3_10cycloalkyl, -(CH2)1-7-C3.7cycloalkyl, -(CH^. 5-C3.5cycloalkyl, -(CH2)1-3-C3.5cycloalkyl, and -CH2- C3cycloalkyl.

In some aspects of the present invention, one or more of the hydrocarbyl groups is independently selected from alkene groups. Typical alkene groups include C C10 alkene group, C C6 alkene group, C C3 alkene group, such as d, C2, C3, C4, C5, Ce, or C7 alkene group. In a preferred aspect the alkene group contains 1 , 2 or 3 C=C bonds. In a preferred aspect, the alkene group contains 1 C=C bond. In some preferred aspects, at least one C=C bond or the only C=C bond is to the terminal C of the alkene chain. The term "oxyhydrocarbyl" group as used herein means a group comprising at least C, H and O and may optionally comprise one or more other suitable substituents. Examples of such substituents may include halo-, alkoxy-, nitro-, an alkyl group, a cyclic group etc. In addition to the possibility of the substituents being a cyclic group, a combination of substituents may form a cyclic group. If the oxyhydrocarbyl group comprises more than one C then those carbons need not necessarily be linked to each other. For example, at least two of the carbons may be linked via a suitable element or group. Thus, the oxyhydrocarbyl group may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for instance, sulphur and nitrogen. In one embodiment of the present invention, the oxyhydrocarbyl group is a oxyhydrocarbon group.

Here the term "oxyhydrocarbon" means any one of an alkoxy group, an oxyalkenyl group, an oxyalkynyl group, which groups may be linear, branched or cyclic, or an oxyaryl group. The term oxyhydrocarbon also includes those groups but wherein they have been optionally substituted. If the oxyhydrocarbon is a branched structure having substituent(s) thereon, then the substitution may be on either the hydrocarbon backbone or on the branch; alternatively the substitutions may be on the hydrocarbon backbone and on the branch.

Typically, the oxyhydrocarbyl group is of the formula C1-60 (such as a C1-30).

Moiety C C is a precursor to a transition metal chelating compound.

In one embodiment, C is a precursor to an iron chelating compound.

In one preferred embodiment, C is a precursor to isonicotinoyl hydrazone, pyridoxal isonicotinoyl hydrazine, 3-hydroxy-1 ,2-dimethyl-4(1 H)-pyridinone, 3-[3,5-Bis(2- hydroxyphenyl)-1 H-1 ,2,3-triazol-1-yl]benzoic acid or kojic acid. In one embodiment, moiety C is connected to moiety M via an oxygen atom.

In one embodiment, C is of Formula lla Formula lla

B is an optionally substituted 5 to 10 membered carbon ring which may contain one or more hetero atoms. In one embodiment, B is an optionally substituted 6-membered ring containing carbon atoms and at least one hetero atom. In one preferred embodiment, B is an optionally substituted pyridine ring.

In one embodiment, B is an optionally substituted 6-membered ring containing carbon atoms. In one embodiment, B is an optionally substituted phenyl ring.

The optional substituents of B are independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, halo, haloalkyl, nitro, nitrile and NR15Ri6, wherein R15 and R16 are independently selected from H and hydrocarbyl.

In one embodiment, ring B is substituted by at least one group selected from OH, Ci-Ci0 alkyl, Ci-C 0 alkoxy, (CHa ioOH, halo, haloalkyl, nitro, nitrile and NR15R16, wherein R 5 and Ri6 are independently selected from H and Ci-C6 alkyl.

In one embodiment ring B is substituted with a group (CH2)nOH where n is from 0 to 10. In one embodiment, n is from 1 to 10. Thus, in one embodiment B is substituted with a group (CH2)i-ioOH. In one embodiment, n is from 1 to 3.

In one embodiment, ring B is a 6 membered hetero aryl ring comprising at least one nitrogen atom, wherein ring B is substituted by at least one C C10 alkyl group and at least one (CH2)i- 10OH group. R13 is H or a hydrocarbyl group. In one embodiment, R 3 is selected from H, C Ci0 alkyl, C C 0 alkenyl, aryl, or hetero aryl, any of which may be optionally substituted. In one embodiment, R 3 is an optionally substituted aryl group. In one embodiment, R 3 is an optionally substituted phenyl group. In one embodiment, R13 is an optionally substituted heteroaryl group comprising at least one nitrogen atom. In a preferred embodiment, Ri3 is an optionally substituted pyridine group. R-,3 may be substituted with one or more substituents independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, halo, haloalkyl, nitro, nitrile and NR 5R 6, wherein R 5 and R 6 are independently selected from H and hydrocarbyl.

In one embodiment, Ri3 may be substituted with at least one group selected from OH, C C10 alkyl, C C 0 alkoxy, (CH2)i-ioOH, halo, haloalkyl, nitro, nitrile and NR15R 6, wherein R15 and R 6 are independently selected from H and C C6 alkyl.

R 4 is H or C C6 alkyl. In one preferred embodiment, R 4 is H. In one preferred

embodiment, R 4 is C C6 alkyl. In one preferred embodiment, R14 is CH3. denotes the point of attachment with M. In one embodiment, B is an optionally substituted 5 to 10 membered carbon ring which may contain one or more hetero atoms, R 3 is H or a hydrocarbyl group, R-, is H or C C6 alkyl, and denotes the point of attachment with M.

In one preferred embodiment, B is an optionally substituted 6 membered phenyl or hetero aryl ring comprising at least one nitrogen atom, Ri3 is an optionally substituted pyridine group, Ri4 is H or CH3 and denotes the point of attachment with M.

In one preferred embodiment, B is an optionally substituted 6 membered phenyl or hetero aryl ring comprising at least one nitrogen atom, R13 is an optionally substituted heteroaryl group comprising at least one nitrogen atom, R 4 is H or CH3 and denotes the point of attachment with . one embodiment, C is of the formula lib

wherein Z is selected from O, NH or N-alkyl, and the ring is further substituted with at least one group selected from alkyl, alkenyl, alkoxy and alkyl-OH, where— denotes the point of attachment with M.

In one embodiment, Z is O. In one embodiment, Z is NH. In one embodiment, Z is N-alkyl, preferably N-Me. In one embodiment, Z is O and the ring is further substituted with alkyl-OH, preferably -CH2 ursor to kojic acid. In one embodiment, C is

where denotes the point of attachment with M. In one embodiment, Z is N-Me and the ring is further substituted with an alkyl group, preferably -CH3. In one embodiment, C is

where denotes the point of attachment with M.

Moiety M M is an optionally substituted cyclic moiety having x number of rings, wherein x is an integer from 1 to 3 and wherein M is at least substituted by OH or NHR ( wherein is H or hydrocarbyl. x is the number of rings present in moiety . Where there is more than one ring present in moiety M, then these rings may be fused or alternatively connected by a linking group (such as a C-C bond). Further, and as described below, may be substituted with one or more groups which either is a ring or forms a ring with a further substituent of M. These additional rings contribute to the total number of rings present in moiety M. Thus, where x is 1 , M is a mono-cyclic moiety and the optional substituents of are not, or do not form, a further ring. Likewise, where M is 2, M may be a monocyclic moiety including a substituent which is itself a ring, or M may be a fused bi-cyclic moiety.

Therefore, in one embodiment, x is 1 and M is a monocyclic moiety. In one embodiment, x is 2 and M is a bi-cyclic moiety, where the rings may or may not be fused. In one embodiment, is a bi-cyclic moiety where the rings are fused together. In one embodiment, M is a bi-cyclic moiety where the rings are not fused together.

In one embodiment, x is 3 and M is a tri-cyclic moiety, where the rings may or may not be fused. Where x is 3, each of the rings may be independently linked to another ring, or more than one of the rings may be fused together. For example, in one embodiment one ring may be linked to two fused rings. In another embodiment, all three rings may be fused together, where either each ring is fused to each of the other rings, or where one ring forms a fused link between the other rings. In a preferred embodiment, x is 1.

In one embodiment, one or each of the rings may contain one or more unsaturated bonds and may contain one or more heteroatoms such as sulphur, nitrogen and oxygen.

In one embodiment, one or each of the rings contains 3 to 10 members. In one

embodiment, the or each of the rings contains 5 to 10 members. In one embodiment, the or each of the rings contains 5 to 8 members. In one embodiment, the or each of the rings contains 5 or 6 members. In one embodiment, the or each of the rings contains 6 members.

In one embodiment, the or each of the rings is a phenyl moiety. In one embodiment, x is 1 and the ring is a phenyl moiety.

In one embodiment, x is 1 and the ring is optionally substituted with one or more substituents independently selected from the group consisting of H, OH, hydrocarbyl, oxyhydrocarbyl, nitro, halo, haloalkyl, nitrile and amino, where hydrocarbyl and oxyhydrocarbyl are as defined above.

In one embodiment, x is 1 and the ring is optionally substituted with one or more substituents independently selected from the group consisting of H, OH, C C10 alkyl, C^C^ alkene, (CH2)i-ioOH, C C10 alkoxy, nitro, halo, haloalkyl, nitrile and amino.

In one embodiment, x is 1 and the ring is a phenyl moiety optionally substituted with one or more substituents independently selected from the group consisting of H, OH, hydrocarbyl, oxyhydrocarbyl, nitro, halo, haloalkyl, nitrile and amino, where hydrocarbyl and

oxyhydrocarbyl are as defined above. In one embodiment, x is 1 and the ring is a phenyl moiety optionally substituted with one or more substituents independently selected from the group consisting of H, OH, C C 0 alkyl, C C10 alkene, Ci-C10 alkoxy, nitro, halo, haloalkyl, nitrile and amino. In one embodiment, x is 1 and the ring is a phenyl moiety substituted with at least one alkene containing group.

As described herein, R^ is selected from H and hydrocarbyl.

In one embodiment, is selected from H and C C 0 alky! group. In a preferred embodiment, Ri is selected from H. In a further preferred embodiment, R- is C1-C10 alkyl, more preferably C C6 alkyl, more preferably C C3 alkyl. In one embodiment, R-i is CH3.

In one embodiment, the, or at least one of the rings of M, is substituted with OH or HR^ and an alkene containing group. Therefore, in one embodiment, the or at least one of the rings of M, is substituted with OH and an alkene containing group. In another embodiment, the or at least one of the rings of M, is substituted with NHR^ and an alkene containing group.

In one embodiment, the or at least one of the rings of IVI is a phenyl group and is substituted with OH or NHR1, and an alkene containing group, wherein the OH or HR^ group and the alkene containing group are ortho to each other on the phenyl ring.

In one embodiment, M is of Formula lie

Formula He

D is a ring comprising from 3 to 10 members. In one embodiment, D is a carbocyclic ring comprising from 5 to 10 members. In one embodiment, D is a carbocyclic ring comprising from 5 to 8 members. In one embodiment, D is a carbocyclic ring comprising from 5 or 6 members. In one embodiment, D is a 6-membered carbocyclic ring. In one embodiment, D is a phenyl ring.

Alternatively, D is a heterocyclic ring comprising from 3 to 10 members including carbon atoms and at least one hetero atom. In one embodiment, D is a heterocyclic ring comprising from 5 to 10 members including carbon atoms and at least one hetero atom. In one embodiment, D is a heterocyclic ring comprising from 5 to 8 members including carbon atoms and at least one hetero atom. In one embodiment, D is a heterocyclic ring comprising 5 or 6 members including carbon atoms and at least one hetero atom. In one embodiment, D is a 5 or 6-membered heteroaryl ring comprising at least one hetero atom. R2 is a substituent independently selected from the group consisting of H, OH, hydrocarbyl, oxyhydrocarbyl, halo, haloalkyl, (CH2)i-i0OH, nitro, nitrile and NR10Rn, wherein R 0 and R^ are independently selected from H and C CB alkyl, wherein each R2 may join together to form a ring optionally containing at least one heteroatom. m is an integer from 0 to 8. In one embodiment, m is from 1 to 8. In one embodiment, m is from 1 to 4. In one embodiment, m is 1. In one embodiment, m is 2.

R3 is H or hydrocarbyl. In one embodiment, R3 is H or C Cs alkyl. In one embodiment, R3 is H. In one embodiment, R3 is CH3.

R4 is OH or NHRi wherein Ri is H or hydrocarbyl. In one embodiment, R is H or Ci-C6 alkyl. In one embodiment, Ri is H. In one embodiment, Ri is C CB alkyl. In one embodiment, R-i is CH3.

R9 is H or hydrocarbyl. In one embodiment, R9 is H or C C6 alkyl. In one embodiment, R9 is H. In one embodiment, Rg is Ci-C6 alkyl. In one embodiment, R9 is CH3. denotes the point of attachment to moiety C. In a preferred embodiment, D is a 5 or 6 membered carbocyclic ring or 5 or 6 membered heteroaryl ring comprising at least one hetero atom; m is 2; each R2 is independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, (CH2)i-ioOH, halo, haloalkyl, nitro, nitrile and NR10R11, wherein R10 and Rn are independently selected from H and C C6 alkyl, wherein each R2 may join together to form a ring optionally containing at least one heteroatom; R3 is H or d-C6 alkyl; R4 is OH or NHR1 wherein Ri is H or C Ci0 alkyl; and— - denotes the point of attachment with C.

In one preferred embodiment, is of Formula lid

Formula lid

R3 is H or hydrocarbyl. In one embodiment, R3 is H or C C6 alkyl. In one embodiment, R3 H. In one embodiment, R3 is Ci-CB alkyl. In one embodiment, R3 is CH3. R4 is OH or NHR-i wherein Ri is H or hydrocarbyl. In one embodiment, R-t is H or GI-L>-IQ alkyl. In one embodiment, R-i is H. In one embodiment, is CrC 0 alkyl. In one embodiment, R-i is CH3.

R5 to R8 are independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, halo, haloalkyl, nitro, (CH2)i-ioQH, nitrite and NR10Rn, wherein R 0 and Rn are independently selected from H and C C6 alkyl, wherein two of R5 to R8 may join together to form a ring optionally containing at least one heteroatom, and wherein denotes the point of attachment with C.

In one embodiment, R5 to R8 are independently selected from H, OH, Ci-C10 alkyl, C C10 alkoxy, halo, haloalkyl, nitro, (CH2)i- 0OH, nitrile and NR10Rn, wherein R10 and R-n are independently selected from H and C C6 alkyl.

In one embodiment, R5 to R8 are independently selected from H, OH, C C6 alkyl, C C6 alkoxy, halo, haloalkyl, nitro, (CH2)i-ioOH, nitrile and NR10Rn, wherein Rio and Rn are independently selected from H and CH3. In one embodiment, R5 to R8 are independently selected from H, C C3 alkyl, C Ce alkoxy, halo, haloalkyl, nitro, (CH2)i-ioOH, and NR10Rii, wherein R10 and R-ι-ι are independently selected from H and CH3.

In one embodiment, at least one of R5 to R8 is C C6 alkoxy. In one embodiment, at least one of Rs to R8 is C C6 alkyl. In one embodiment, at least one of R5 to R8 is halo. In one embodiment, at least one of R5 to R8 is haloalkyl. In one preferred embodiment, at least one of R5 to R8 is CF3.

In one embodiment, at least one of R5 to RB is NR10Rn, wherein R 0 and Ri-, are

independently selected from H and CH3. In one embodiment, R10 and Rn are both CH3. In one embodiment, Ri0 and R-H are both H. In one embodiment, two of Rs to R8 join together to form a ring optionally containing at least one heteroatom. In one embodiment, two of R5 to R8 join together to form a ring containing two hetero atoms. In one embodiment, two of R5 to R8 join together to form a ring containing two oxygen atoms. In one embodiment, two of R5 to R8 join together to form a ring containing two nitrogen atoms.

In one embodiment, two of R5 to R8 join together to form a ring of the following structure

Rg is H or hydrocarbyl. In one embodiment, R9 is H or C C10 alkyl. In one embodiment, R9 is H. In one embodiment, R9 is C C10 alkyl. in one embodiment, R9 is CH3.

In one preferred embodiment, R3 is H or C CB alkyl, R4 is OH or NHRi wherein Ri is H or C Cio alkyl, R5 to R8 are independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, (CH2)i-ioOH, halo, haloalkyl, nitro, nitrile and NRi0Rn, wherein R10 and R-n are independently selected from H and C C6 alkyl, wherein two of R5 to R8 may join together to form a ring optionally containing at least one heteroatom, R9 is H or C C10 alkyl, and denotes the point of attachment with C. In a further preferred embodiment, R3 is H or CH3, R4 is OH or NH2, and R5 to R8 are independently selected from H, hydroxyl, Ci-C3 alkyl, C Ce alkoxy, C C6 haloalkyl and NR10Rn wherein R10 and Rn are independently selected from H and C C6 alkyl, and R9 is H or CfC1D alkyl.

In a further preferred embodiment, R3 is H or CH3, R4 is OH or NHRi wherein R-i is alkyl, and R5 to R8 are independently selected from H, hydroxyl, C C6 alkyl, CrC6 alkoxy, C Ce haloalkyl and NR 0Rn wherein R 0 and are independently selected from H and C C6 alkyl, and R9 is H or C Cw alkyl.

C-M

As described above, the connection between C and M is photolabile when exposed to ultraviolet-A (UVA) radiation so as to yield a first compounds which is a transition metal chelating compound and a second compound which is a cyclic compound having x+1 rings.

In this regard, it is known that ultraviolet-A radiation has a wavelength in the region of from about 320 nm to 400 nm. Thus, in one embodiment, the connection between C and M is photolabile when exposed to electromagnetic radiation having a wavelength in the region of from about 320 nm to 400 nm so as to be cleaved to yield a first compound which is a transition metal chelating compound as defined herein and a second compound which is a cyclic compound as defined herein.

Particularly Preferred Embodiments

In one preferred embodiment, the compound of the present invention is of formula Ilia Formula Ilia wherein B, D, R2 , R3, R4, R9, R13, Ri4 and m are as defined above. In one preferred embodiment, the compound of the present invention is of formula lllb

Formula lllb wherein B is an optionally substituted 6 membered phenyl or hetero aryl ring comprising at least one nitrogen atom, R 3 is an optionally substituted heteroaryl group comprising at least one nitrogen atom, R-u is H or CH3; and

D, R2, R3, R4, R9 and m are as defined above.

In one preferred embodiment, the compound of the present invention is of formula lllc

Formula 1 lie wherein B and R3 to R1 are as defined above.

In one preferred embodiment, the compound of the present invention is of formula llld

Formula llld wherein B is an optionally substituted 5 to 10 membered carbon ring which may contain one or more hetero atoms, R13 is H or a hydrocarbyl group, R14 is H or Ci-C6 alkyl;

R4 is OH or NHR-i wherein Ri is H or hydrocarbyl;

R5 to R8 are independently selected from H, OH, hydrocarbyl, oxyhydrocarbyl, (CH2)i-ioOH, halo, haloalkyl, nitro, nitrile and NR10Rn, wherein R10 and Rn are independently selected from H and C C6 alkyl, wherein two of R5 to R8 may join together to form a ring optionally containing at least one heteroatom; and

R9 is H or C C 0 alkyl. In one preferred embodiment, the compound of the present invention is of formula Ille

wherein B is an optionally substituted 6 membered phenyl or hetero aryl ring comprising at least one nitrogen atom, Ri3 is an optionally substituted heteroaryl group comprising at least one nitrogen atom, R14 is H or CH3;

R4 is OH or NHR1 wherein Ri is H or C1-C3 alkyl;

R5 to R8 are independently selected from H, hydroxy!, C C8 alkyl, C C6 alkoxy, (CH2)i.-ioOH, Ci-C6 haloalkyl and NR10Rn wherein R10 and R-n are independently selected from H and C C6 alkyl, wherein two of R5 to R8 may join together to form a ring optionally containing at least one heteroatom; and

Rg is H Or U1-U10 alkyl.

In one preferred embodiment, the compound of the present invention is of formula Illf

wherein D, R2, R3, R4l Rg and m are as defined above. In one preferred embodiment, the compound of the present invention is of formula lllg or lllh

22





Compositions

The compounds of the present invention defined herein can be used as part of a

composition. In particular, the presently defined compounds can be used in combination with one or more dermatologically acceptable carriers. Therefore, in a further aspect the present invention is related to compositions comprising a compound as defined herein and one or more dermatologically acceptable carriers.

The term dermatologically acceptable carrier refers to all carriers and/or excipients and/ or diluents conventionally used in topical preparations.

Preferably, the topical compositions according to the present invention are in the form of a suspension or dispersion in solvents or fatty substances, or alternatively in the form of an emulsion or micro emulsion (in particular of O W-type), PIT-emulsion, multiple emulsion (e.g. O/W/O-type and W/O/W), pickering emulsion, one- or multiphase solution or vesicular dispersion or other usual forms, which can also be applied by pens, as masks or as sprays. If the topical preparation is or comprises an emulsion it can also contain one or more anionic, nonionic, cationic or amphoteric surfactant(s). !n a particular preferred embodiment, the topical compositions according to the invention are O/W emulsions.

Preferred topical compositions according to the invention are sun care preparations.

Topical compositions in accordance with the invention can be in the form of a liquid, lotion, a thickened lotion, a gel, a cream, a milk, an ointment, a paste or a make-up, and can be optionally packaged as an aerosol and can be provided in the form of a mousse such as an aerosol mousse, a foam or a spray foam, a spray, a stick. In accordance with the present invention, the topical compositions according to the invention may optionally be combined with further ingredients such as ingredients for skin lightening; treatment of

hyperpigmentation; preventing or reducing acne, wrinkles, lines, atrophy and/or

inflammation; anti-cellulites and slimming (e.g. phytanic acid), firming, moisturizing and energizing, self-tanning, soothing, as well as agents to improve elasticity and skin barrier and/or further carriers and/or excipients or diluents conventionally used in topical compositions. The necessary amounts of the cosmetic and dermatological adjuvants and additives can, based on the desired product, easily be determined by the skilled person.

Preferred examples of further ingredients are vitamin C (ascorbic acid) and/or its derivatives (e.g. ascorbyl phosphate such as Stay C (sodium ascorbyl monophosphate) from DS Nutritional Products Ltd.), folic acid, niacinamide, vitamin A and/or its derivatives (e.g., retinoid derivatives such as retinyl palmitate or retinyl propionate), vitamin E and/or its derivatives (e.g., tocopherol acetate), vitamin B6, vitamin B12, biotin, co-enzyme Q10, EGCG, hydroxytyrosol and/or olive extract, shea butter, algae extract, cocoa butter, aloe extract, jojoba oil, echinacea extract, chamomile extract, water melon extract such as e.g. Pepha Protect commercially available at DSM Nutritional Products Ltd., glycyrrhetinic acid, glycyryca glabra extract, in particular vitamin E and/or its derivatives, shea butter, algae extract, cocoa butter, aloe extract and/ or vitamin A and/or its derivatives. The additional cosmetically active ingredient is typically included in an amount of at least 0.001 wt. % based on the total weight of the topical preparation. Generally, an amount of about 0.001 wt. % to about 30 wt. %, preferably from about 0.001 wt. % to about 10 wt. % of an additional cosmetically active agent is used. A vitamin E derivative for use in the present invention is tocopheryl acetate. Tocopheryl acetate may be present in the topical preparations in an amount from about 0.05 wt.-% to about 25 wt.-%, in particular 0.5 wt.-% to 5 wt.-%. Another vitamin E derivative of interest is tocopheryl linoleate. Tocopheryl linoleate may be present in the skin care composition in an amount from about 0.05 wt.-% to about 25 wt.-% in particular .05 wt.-% to 5 wt.-%. Vitamin A and/or its derivatives in particular retinoid derivatives such as retinyl palmitate or retinyl propionate is preferably used in the topical preparations according to the invention in an amount of 0.01 - 5 wt.-%, in particular 0.01 - 0.3 wt.-%.

However, in one embodiment it is envisaged that no additional active ingredients are added to the composition. Thus, in this embodiment the composition will consist essentially of a compound as defined herein and a dermatologically acceptable carrier.

The topical compositions of the invention can also contain usual cosmetic adjuvants and additives, provided that they do not interfere with the interaction of UVA with the compound of the present invention. Such adjuvants or additives include preservatives/ antioxidants, fatty substances/ oils, water, organic solvents, silicones, thickeners, softeners, emulsifiers, antifoaming agents, moisturizers (such as e.g. glycerine, propyleneglycol), aesthetic components such as fragrances, surfactants, fillers, sequestering agents, anionic, cationic, nonionic or amphoteric polymers or mixtures thereof, propellants, acidifying or basifying agents, dyes, abrasives, absorbents, essential oils, skin sensates, astringents, antifoaming agents, pigments or nanopigments, or any other ingredients usually formulated into cosmetic compositions but which do not interfere with the interaction of UVA with the compound of the present invention. Such cosmetic ingredients commonly used in the skin care industry, which are suitable for use in the compositions of the present invention are e.g. described in the CTFA Cosmetic Ingredient Handbook, Second Edition ( 992) without being limited thereto.

The necessary amounts of the cosmetic and dermatological adjuvants and additives can, based on the desired product, easily be chosen by a skilled person in this field.

Of course, one skilled in this art Will take care to select the above mentioned optional additional compound or compounds and/or their amounts such that the advantageous properties intrinsically associated with the combination in accordance with the invention are not, or not substantially, detrimentally affected by the envisaged addition or additions. Further, the composition of the present invention can include independent UVB-filter substances. Such UVB-filter substances comprise all groups which absorb light in the range of wavelengths 290 nm to 320 nm and which are or can be used as cosmetically acceptable UVB-filter substances. Such UVB-filter substances are e.g. listed in the CTFA Cosmetic ingredient Handbook or "The Encyclopedia of Ultraviolet Filters" (ISBN: 978-1-932633-25-2) by Nadim A. Shaath.

The composition may comprise further UV-filter substances such as in particular IR- or UVC- filter substances. Such filter substances are e.g. listed in the CTFA Cosmetic ingredient Handbook or "The Encyclopedia of Ultraviolet Filters" (ISBN: 978-1-932633-25-2) by Nadim A. Shaath.

Suitable UVB-filter substances may be organic or inorganic compounds. Exemplary UVB- filter substances encompass e.g. acrylates such as e.g. 2-ethylhexyl 2-cyano-3,3- diphenylacrylate (octocrylene, PARSOL® 340), ethyl 2-cyano-3,3-diphenylacrylate;

Camphor derivatives such as e.g. 4-methyl benzylidene camphor (PARSOL® 5000), 3- benzylidene camphor, camphor benzalkonium methosulfate, polyacrylamidomethyl benzylidene camphor, sulfo benzylidene camphor, sulphomethyl benzylidene camphor, terephthalylidene dicamphor sulfonic acid (Mexoryl® SX); cinnamate derivatives such as e.g. ethylhexyl methoxycinnamate (PARSOL® MCX), ethoxyethyl methoxycinnamate, isoamyl methoxycinnamate as well as cinnamic acid derivatives bond to siloxanes; p- aminobenzoic acid derivatives such as e.g. p-aminobenzoic acid, 2-ethylhexyl p- dimethylaminobenzoate, N-oxypropylenated ethyl p-aminobenzoate, glyceryl p- aminobenzoate; benzophenones such as e.g. benzophenone-3, benzophenone-4, 2,2',4,4'- tetrahydroxy-benzophenone, 2,2'-dihydroxy-4,4'- dimethoxybenzophenone; esters of benzalmalonic acid such as e.g. di-(2-ethylhexyl) 4- methoxybenzalmalonate;

organosiloxane compounds carrying chromophore groups such as e.g. polysilicones-15 (PARSOL® SLX), drometrizole trisiloxane (Mexoryl® XL); imidazole derivatives such as e.g. 2-phenyl benzimidazole sulfonic acid (PARSOL® HS) and salts thereof such as e.g. sodium- or potassium salts, ammonium salts, morpholine salts, salts of primary, sec. and tert. amines like monoethanolamine salts, diethanolamine salts; salicylate derivatives such as e.g.

isopropylbenzyl salicylate, benzyl salicylate, butyl salicylate, ethylhexyl salicylate (PARSOL® EHS, Neo Heliopan® OS), isooctyl salicylate or homomenthyl salicylate (homosalate, PARSOL® HMS, Neo Heliopan® HMS); triazine derivatives such as e.g. ethylhexyl triazone (Uvinul<(R)> T-150), diethylhexyl butamido triazone (Uvasorb® HEB), bis- ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb® S); Benzotriazole derivatives such as e.g. 2,2'-methylene~bis-(6-(2H-benzotriazole-2-yl)-4- (1 ,1 ,3,3,-tetramethylbutyl)-phenol (Tinosorb® M); encapsulated UV-filters such as e.g. encapsulated ethylhexyl

methoxycinnamate (Eusolex® UV-pearls) or microcapsules loaded with UV-filters; Inorganic UV-filter substances encompass pigments such as e.g. microparticulated zinc oxide or titanium dioxide (e.g. commercially available as PARSOL® TX). The term

"microparticulated" refers to a particle size from about 5 nm to about 200 nm, particularly from about 15 nm to about 100 nm. The particles may also be coated by other metal oxides such as e.g. aluminum or zirconium oxides or by organic coatings such as e.g. polyols, methicone, aluminum stearate, alkyl silane. Such coatings are well known in the art. The total amount of the additional UVB-filter substance in the topical compositions according to the invention is preferably in the range of about 1 to 40 wt.-%, preferably in -the range of about 5 to 30 wt.-%, in particular in the range of 10 to 30 wt.-% with respect to the total weight of the topical composition. Preferred UVB-filter substances according to the invention encompass polysilicones-15, phenylbenzimidazol sulfonic acid, octocrylene, ethylhexyl methoxycinnamate, ethyl hexylsalicylate and/ or homosalate.

In order to enhance the photostability of sun care products it may be desirable to add an independent photostabilizer, i.e. a photostabilizer which is in addition to the compound produced when the compound as defined herein is exposed to ultraviolet-A radiation.

Exemplary photostabilizers known to a skilled person in the art encompass e.g. 3,3- diphenylacrylate derivatives such as e.g. octocrylene (PARSOL® 340) or Polyester-8 (Polycrylene®); Methoxycrylene (Solastay), benzylidene camphor derivatives such as e.g. 4- methyl benzylidene camphor (PARSOL® 5000); benzalmalonate derivatives such as e.g. polysilicones-15 (PARSOL® SLX) or diethylhexyl syringylidene malonate (Oxynex ST liquid); dialkyl naphthalates such as diethylhexyl naphthalate (Corapan TQ) without being limited thereto. An overview on further stabilizers is e.g. given in 'SPF Boosters & Photostability of Ultraviolet Filters', HAPPI, October 2007, p. 77-83 which is included herein by reference. The photostabilizers are generally used in an amount of 0.05 to 10 wt.-% with respect to the total weigh of the topical composition.

The compositions of the present invention are intended to be applied topically. Thus, in one embodiment the composition of the present invention is a topical composition. The term "topical composition" as used herein refers in particular to cosmetic compositions that can be topically applied to mammalian keratinous tissue such as e.g. human skin or hair, particularly human skin.

The term "cosmetic composition" as used in the present application refers to cosmetic compositions as defined under the heading "Kosmetika" in Rompp Lexikon Chemie, 10th edition 1997, Georg Thieme Verlag Stuttgart, New York as well as to cosmetic preparations as disclosed in A. Domsch, "Cosmetic Preparations", Verlag fur chemische Industrie (ed. H. Ziolkowsky), 4th edition, 1992.

BRIEF DESCRIPTION OF FIGURES Figure 1 shows a schematic overview of a compound of the present invention being acted upon by UVA radiation to produce a first compound which is an iron chelator and a second compound which is a UV filter or antioxidant.

Figure 2 shows a schematic overview of preferred subset of compounds of the present invention being acted upon by UVA.

Figure 3 shows the HPLC monitoring of UVA induced uncaging in-vitro of aminocinnamoyl- PIH to PIH and hydroxycinnamoyl-SIH to SIH respectively. Plots represent the percentage of relative peak areas of the caged compounds and the free chelators collected at 280 nm post-UVA. Figure 4 shows the flow cytometric evaluation of percentage of live and dead HaCaT keratinocytes treated with DFO and PIH for 72 hours.

Figure 5 shows the flow cytometric evaluation of percentage of cells in S phase in HaCaT keratinocytes treated with DFO and PIH for 72 hours (BrdU assay).

Figure 6 shows a morphological study of DED-Raft HaCaT cultures treated with 100uM DFO and PIH for 72h.

Figure 7 shows a morphological study of DED-Raft HaCaT cultures treated with 100uM PIH or caged-PIH (10) (non-irradiated or pre-irradiated with UVA) for 72h.

The present invention will now be described with reference to the following non-limiting examples. EXAMPLES

In the examples the following abbreviations have the indicated meanings:

AcOH - acetic acid

CEETP - (carbethoxyethylidene)triphenylphosphorane; ethyl-2-(triphenylphosphoranylidene) propionate

DCM - dichloromethane

DIPEA - A/,A-diisopropylethylamine

DMF - /V,N-dimethylformamide

DMAP - 4-dimethylaminopyridine

DMSO - dimethylsulfoxide

EDC.HCI - 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide ESI - electrospray ionisation

Et3N - triethylamine

Et20 - diethyl ether

EtOAc - ethyl acetate

EtOH - ethanol

INH - isonicotinoylhydrazide

MeOH - methanol

Pyr - pyridyl

RT - room temperature

SIH - salicylaldehyde isonicotinoyl hydrazone

TBS-CI - fe/f-butyldimethylsilyl chloride

TBDPS - terf-butyldiphenylsilyl

THF - tetrahydrofuran

1. Preparation of compounds

Preparation 1

(£)-iert-ButyldimethyIsilyl-3-(2-(ierf-butyldimethyIsilyIoxy)phenyl)acrylate

A solution of frans-2-hydroxycinnamic acid (1.04 g, 6.34 mmol), imidazole (938 mg, 13.78 mmol) and ferf-butyldimethylsilylchloride (2.04 g, 13.54 mmol) in anhydrous DMF (20 mL) was stirred under argon at RT overnight, and then 60 °C for 2 h. The solvent was evaporated off to give an oil which was dissolved in DCM (40 mL) and washed with H20 (3 χ 40 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the crude product, which was purified by column chromatography on silica gel, eluting with 0-2% MeOH in DCM. This gave the title compound as a pale yellow oil (1.82 g, 73%). Rf = 0.82 (10% MeOH in DCM). 1H NMR (CDCI3, 400 MHz) δ: 0.24 (6H, s, Si(CH3)2), 0.32 (6H, s, Si(CW3)2), 0.98 (9H, s, C(CH3)3), 1.01 (9H, s, C(CH3)3), 6.37 (1H, d, J = 16.1 , ArCH=CWC02Si), 6.83 (1 H, dd, J = 8.2, 1.0, ArH), 6.95 (1 H, t, J = 7.6, ArH), 7.26 (1 H, td, J = 7.8, 1.7, ArH), 7.53 (1 H, dd, J = 7.8, 1.7, ArH), 7.96 (1 H, d, J = 16.1 , ArCH=CH). 13C NMR (CDCIg, 100 MHz) δ: -4.67, -4.21 , 17.81 , 18.31 , 25.72, 25.79, 119.70, 120.00, 121.43, 125.92, 127.68, 131.1 1 , 140.16, 154.47, 167.16. Preparation 2

(E)-ferf-Butyldimethylsilyl-3-(2,4-J /'s(iert-b^

A solution of frans-2,4-dihydroxycinnamic acid (3.00 g, 16.7 mmol), imidazole (3.6 g, 52.5 mmol) and ferf-butyldimethylsilylchloride (8.30 g, 55.0 mmol) in anhydrous DMF (60 mL) was stirred under argon at RT overnight. The solvent was evaporated off to give an oil which was dissolved in DC (150 mL) and washed with H20 (3 χ 100 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the crude product, which was purified by column chromatography on silica gel eluting with 1-2% EtOAc in petroleum ether. This gave the title compound as a colourless oil which solidified upon storing at 2-8 °C to a white solid (5.05 g, 58%). 1H NMR (CDCI3, 400 MHz) 6: 0.21 (6H, s, Si(CH3)2), 0.25 (6H, s, Si(CH3)2), 0.32 (6H, s, Si(CH3)2), 0.98 (9H, s, C(Ctf3)3), 0.98 (9H, s, C(Ctf3)3), 1 02 (9H, s, C(CW3)3), 6.27 (1 H, d, J = 16.0, ArCH=CHC02Si), 6.32 (1 H, d, J = 2.3, ArH), 6.47 (1 H, dd, J = 8.6, 2.3, ArH), 7.42 (1H, d, J = 8.6, ArH), 7.90 (1H, d, J = 16.0, ArCH=CH). 13C NMR (CDCI3, 100 MHz) δ: -4.65, -4.42, -4.20, 17.80, 18.18, 18.31 , 25.56, 25.75, 25.79, 111.24, 114.05, 117.65, 119.55, 128.50, 139.96, 155.68, 158.51 , 167.35.

Preparation 3

(£)-Ethyl-3-(4,5-dimethoxy-2-nitrophenyI)-2-methyl acrylate

A solution of 6-nitroveratraldehyde (4.00 g, 18.94 mmol) and CEETP (8.09 g, 22.33 mmol) in anhydrous toluene (200 mL) was heated at 85°C under argon for 19 h. The solvent was evaporated off and the resulting crude product was purified by column chromatography on silica gel, eluting with DCM, to give the title compound as a yellow solid (5.36 g, 96%). Rf = 0.53 (DCM). Mp = 143-145 °C. H NMR (CDCI3, 400 MHz) δ: 1.34 (3H, t, J = 7.1 , CH2CH3), 1.90 (3H, s, CH=C(CH3)), 3.91 (3H, s, OCH3), 3.95 (3H, s, OCH3), 4.27 (2H, q, J = 7.1 , CH2CH3), 6.70 (1 H, s, ArH), 7.72 (1 H, s, ArH), 7.91 (1 H, s, Ctf=C(CH3)). 13C NMR (CDCl3, 100 MHz) δ: 14.08, 14.28, 56.44, 56.50, 61.05, 107.91 , 112.38, 126.63, 129.49, 136.44, 140.39, 148.64, 153.03, 167.78.

Preparation 4

(E)-3-(4,5-Dimethoxy-2-nitrophenyl)-2-methyIacrylic acid

A solution of (E)-ethyI-3-(4,5-dimethoxy-2-nitrophenyl)-2-methyl acrylate (0.9 g, 3.05 mmol) in THF (26 mL) was treated with 1M NaOH (9.2 mL) and EtOH (5 mL) and stirred at room temperature for 41 h. The organic solvents were evaporated off and the pH of the remaining aqueous solution was adjusted to pH 3 with 6M HCI. The resulting suspension was extracted with EtOAc (3 x 100 ml_), and the combined organic extracts were dried (MgSO,,), filtered, and the solvent evaporated to give the title compound as a yellow solid (763 mg, 94%). f = 0.67 (10% MeOH in DCM). Mp = 255-259 °C 1H NMR (acetone-ds, 270 MHz) δ: 1.91 (3H, s, CH=C(CW3)), 3.98 (3H, s, OCH3), 4.01 (3H, s, OCH3), 7.02 (1 H, s, ArH), 7.75 (1 H, s, ArH), 7.92 (1 H, s, CH=C(CH3)). 13C NMR (DMSO-d6, 100 MHz) δ: 13.80, 56.13, 56.48, 107.82, 1 12.86, 125.73, 129.53, 135.43, 139.86, 148.25, 152.90 , 168.71.

Preparation 5

(E)-3-(2-Amino-4,5-dimethoxyphenyl)-2-methyIacrylic acid

A solution of (E)-3-(4,5-dimethoxy-2-nitrophenyl)-2-methylacrylic acid (1.00 g, 3.74 mmol), iron powder (1.4 g, 26.2 mmol) and AcOH (12 mL) in 66% aqueous EtOH (18 mL) was heated at reflux for 1 h. The reaction mixture was filtered through ceiite and the EtOH was evaporated off. The resulting suspension was diluted with H20, extracted with EtOAc (4 x 80 mL), and the combined organic extracts were dried (MgS04), filtered, and the solvent evaporated. This gave the title compound as a dark yellow solid (521 mg, 60%). Rf = 0.34 (8% MeOH in DCM). Mp = 159-161 °C. H NMR (CDCI3, 400 MHz) δ: 2.08 (3H, s, CH=C(CH3)), 3.81 (3H, s, OCH3), 3.86 (3H, s, OCH3), 6.30 (1 H, s, ArH), 6.74 (1 H, s, ArH), 7.73 (1 H, s, CH=C(CH3)). 13C NMR (CDCI3) 100 MHz) δ: 14.01 , 55.75, 56.57, 100.23, 1 12.28, 113.16, 126.50, 136.75, 139.87, 141.62, 150.89, 173.68.

Preparation 6 (E)-2-MethyI-3-(6-nitrobenzo[oQ[1,3]dioxyl-5-yl) acrylate

A solution of 6-nitropiperonal (2.00 g, 10.25 mmol) and CEETP (4.09 g, 11.29 mmol) in anhydrous toluene (100 mL) was heated at 65°C under argon for 19 h. The solvent was evaporated and the resulting crude solid was purified by column chromatography on silica gel eluting with DCM to give the title compound as a bright yellow solid (1.64 g, 84%). Rf = 0.35 (DCM). Mp = 1 18-121 °C. 1H NMR (CDCI3, 400 MHz) δ: 1.33 (3H, t, J = 7.1 , CH2CH3), 1.89 (3H, s, CH=C(CW3)), 4.26 (2H, q, J = 7.1 , CH2CH3), 6.15 (2H, s, OCH20), 6.69 (1 H, s, ArH), 7.64 (1H, s, ArH), 7.83 (1 H, s, CH=C(CH3)). 13C NMR (CDCI3) 400 MHz) δ: 13.96, 14.25, 61.05, 103.24, 105.62, 109.71 , 128.72, 129.70, 136.07, 142.02, 147.83, 151.81 ,' 167.64. Preparation 7

(E)-2-Methyl-3-(6-nitrobenzo[cfl[1,3]dioxyl-5-yl) acrylic acid A solution of (EJ-a-methyl-S-ie-nitrobenzoIdltl.Sldio yl-S-yl) actylate (2.00 g, 7.16 mmol) in THF (52 mL) was treated with 1 M NaOH (22 mL) and EtOH (13 mL) and stirred at room temperature for 22 h. The organic solvents were evaporated off and the pH of the remaining aqueous solution was adjusted to pH 4 with 6M HCI. The resulting suspension was extracted with EtOAc (3 χ 100 mL), and the combined organic extracts were dried ( gS04), filtered, and the solvent evaporated to give the title compound as an orange solid (840 mg, 93%). Rf = 0.61 (10% MeOH in DCM). Mp = 189-202 °C. 1H N R (CD3OD, 270 MHz) δ: 1.81 (3H, s, CH=C(CH3)), 6.26 (2H, s, OCH20), 7.07 (1 H, s, ArH), 7.68 (1 H, s, ArH), 7.76 (1 H, s, CH=C(CH3)), 11.95 (1 H, s, C02H). 13C NMR (DMSO-d6, 100 MHz) δ: 13.50, 103.61 , 104.95, 109.50, 127.88, 129.54, 135.30, 141.53, 147.65, 151.78, 168.50.

Preparation 8

(£)-3-(6-aminobenzo[d][1 ,3]dioxoI-5-yI)-2-methylacrylic acid

A solution of (E)-2-methyl-3-(6-nitrobenzo[d][1,3]dioxyl-5-yl) acrylate (300 mg, 1.19 mmol), iron powder (466 mg, 26.2 mmol) and AcOH (3.6 mL) in 66% aqueous EtOH (5.4 mL) was heated at reflux for 1 h. The reaction mixture was filtered through celite and the EtOH was evaporated off. The resulting suspension was diluted with HzO, extracted with EtOAc (4 x 80 mL), and the combined organic extracts were dried (MgS04), filtered, and the solvent evaporated. This gave (E)-3-(6-aminobenzo[o(l[1,3]dioxol-5-yl)-2-methyl acrylic acid as a dark yellow solid (220 mg, 84%). Rf = 0.10 (8% MeOH in DCM). Mp = 191-194 °C. 1H NMR (DMSO-ds, 400 MHz) δ: 1.99 (3H, s, CH=C(Ctf3)), 5.03 (2H, s, NH2), 5.93 (2H, s, OCH20), 6.42 (1 H, s, ArH), 6.73 (1 H, s, ArH), 7.50 (1H, s, CH=C(CH3)), 12.24 (1H, s, C02H). 13C NMR (DMSO-d6, 100 MHz) δ: 14.25, 96.80, 100.36, 108.29, 111.33, 125.37, 134.74, 138.21 , 143.55, 148.34, 169.72.

Preparation 9 (£)-Ethyl 2-methyI-3-(2-nitro-4-(trifluoromethyl)phenyl) acrylate

A solution of 2-nitro-4-(trifluoromethyl)benzaldehyde (800 mg, 3.65 mmol) and CEETP (1.56 g, 4.4 mmol) in anhydrous toluene (35 mL) was heated at 65°C under argon for 19 h. The solvent was evaporated to give the crude product which was purified by column chromatography on silica gel, eluting with DCM to give the title compound as a yellow- orange oil (862 mg, 78%). Rf = 0.82 (DCM). 1H NMR (CDCI3, 400 MHz) δ: 1.24 (3H, t, J = 7.2, CH2CH3), 1.81 (3H, d, J = 1.3, CH=C(CH3)), 4.18 (2H, q, J = 7.2, CH2Ctf3), 7.51 (1 H, d, J = 8.1 , ArH), 7.77 (1 H , s, CH=C(CH3)), 7.86 (1 H, dd, J = 8.1 , 1.6, ArH), 8.27 (1 H, d, J = 1.3, ArH). 3C NMR (CDCI3, 100 MHz) δ: 13.89, 14.07, 61.23, 122.11 , 123.97, 126.68, 129.58, 131.52, 132.30, 133.58, 135.47, 147.69, 166.96.

Preparation 10

(E)-2-Methyl-3-(2-nitro-4-(trifluoromethyl)phenyl)acrylic acid A solution of (E)-ethyI 2-methyl-3-(2-nrtro-4-(trifluoromethyl)phenyl) acrylate (850 mg, 2.8 mmol) in THF (24 mL) was treated with 1 M NaOH solution (8.4 mL) and EtOH (6 mL) and stirred at 40 °C overnight. The organic solvents were evaporated off and the pH of the remaining aqueous solution was adjusted to pH 4 with 10% aqueous HCI. The resulting suspension was diluted with H20 and extracted with EtOAc (3 χ 50 mL). The combined organic extracts were dried (MgS0 ), filtered, and the solvent evaporated to give the title compound as a pale yellow solid (757 mg, 98%). Rf = 0.14 (4% MeOH in DCM). Mp = 144- 146 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 1.89 (3H, s, CH=C(CW3)), 7.81 (1 H, s, CH=C(CH3)), 7.84 (1 H, d, J = 8.1 , ArH), 8.23 (1 H, dd, J = 8.2, 1.3, ArH), 8.53 ( H, d, J = 8.2, ArH), 12.89 (1 H, br, C02H). 13C NMR (DMSO-d6, 100 MHz) δ: 13.80, 121.82, 124.27, 129.27, 129.60, 130.04, 132.07, 133.32, 135.11 , 147.78, 68.24.

Preparation 11

(£)-3-(2-Amino-4-(trifluoromethyl)phenyI)-2-methylacryIic acid

A solution of (£)-2-methyl-3-(2-nitro-4-(trifIuoromethyl)phenyl)acrylic acid (740 mg, 2.69 mmol) in glacial AcOH (8 mL) and 66% EtOH (12 mL) was treated with iron powder (1.05 g, 18.8 mmol) and stirred at reflux for 70 min. The cooled reaction mixture was filtered through celite, and the celite pad washed thoroughly with EtOH. The combined filtrates were evaporated to give a black oil which was dissolved in H20 (40 mL), and was extracted with EtOAc (2 x 40 mL). The combined organic extracts were washed with further H20 (40 mL), dried (Na2S04), filtered, and the solvent evaporated to give the crude product as a black oil. Purification by column chromatography on silica gel, eluting with 10% MeOH in DCM gave the title compound as a dark brown solid (543 mg, 82%). Rf = 0.47 (10% MeOH in DCM). Mp = 161-165 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 1.95 (3H, s, CH=C(CH3)), 5.62 (2H, s, NHZ), 6.89 (1H, d, J = 7.1 , ArH), 7.07 (1 H, s, CH=C(CH3)), 7.27 (1 H, d, J =7.1 , ArH), 7.50 (1 H, s, ArH), 12.51 (1 H, br, COzH). 3C NMR (DMSO-de, 100 MHz) δ: 14.19, 1 0.87, 1 11.28, 123.10, 125.70, 129.21 , 129.52, 130.26, 133.52, 147.34 (Ar), 169.09.

Preparation 12

(£)-EthyI 2-methyl-3-(2-nitrophenyl)acrylate A solution of 2-nitrobenzaldehyde (1.0 g, 6.62 mmol) and CEETP (2.9 g, 7.94 mmol) in anhydrous toluene (40 mL) was stirred at 65 °C under argon overnight. The solvent was evaporated and the crude product was purified by column chromatography on silica gel, eluting with DCM to give the title compound as a yellow oil (1.6 g, 99%). Rf = 0.32 (DCM). 1H NMR (CDCI3, 400 MHz) δ: 1.35 (3H, t, J = 7.2, CH2CH3), 1.89 (3H, s, CH=C(CH3)), 4.30 (2H, q, J = 7.2, CH2CH3), 7.36 (1 H, d, J = 7.6, ArH), 7.50 (1H, td, J = 8.0, 0.9, ArH), 7.64 (1 H, td, J = 7.6, 1.0, ArH), 7.89 (1 H, s, Ctf=C(CH3)), 8.12 (1 H, dd, J = 8.0, 1.2, ArH). 13C NMR (CDCI3, 100 MHz) δ: 13.88, 14.18, 61.03, 124.75, 128.83, 130.49, 131.23, 131.89, 133.13, 135.23, 147.78, 167.52. Preparation 13

(£)-2-WIethyI-3-(2-nitrophenyl)acryIic acid

A solution of (E)-ethyl 2-methy[-3-(2-nitrophenyl)acrylate (1.4 g, 5.95 mmol) in THF (32 mL) was treated with 1 M NaOH solution (21 mL) and EtOH (8 mL) and stirred at 40 °C overnight. The organic solvents were were evaporated off and the pH of the remaining aqueous solution was adjusted to pH 2 with 10% aqueous HCI solution. The resulting suspension was diluted with H20 (30 mL), and extracted with EtOAc (2 x 80 mL). The combined organic extracts were dried (MgS04), filtered, and the solvent evaporated to give the title compound (1.2 g, 97%) as a light yellow solid. Rf = (5% MeOH in DCM). Mp = 196- 201 0 C. 1H NMR (DMSO-d6l 400 MHz) δ: 1.87 (3H, s, CH=C(CH3)), 7.59 (1 H, d, J = 7.6, ArH), 7.70 (1 H, t, 8.0, ArH), 7.81 (1 H, s, Ctf=C(CH3)), 7.86 (1 H, t, J = 7.6, ArH), 8.20 (1H, d, J = 8.0, ArH), 12.75 (1H, s, C02H). 13C NMR (DMSO-d6, 100 MHz) δ: 13.73, 124.60, 129.47, 130.52, 130.91 , 131.33, 133.75, 134.51 , 147.56, 168.53.

Preparation 14

(£)-3-(2-Aminophenyl)-2-methylacryIic acid A solution of (£)-2-methyl-3-(2-nitrophenyI)acrylic acid (500 mg, 2.41 mmol) in glacial AcOH (6 mL) and 66% EtOH (9 mL) was treated with iron powder (940 mg, 16.9 mmol) and stirred at reflux for 75 min. The cooled reaction mixture was filtered through celite, and the celite pad washed thoroughly with EtOH and EtOAc. The combined filtrates were evaporated to give a dark brown residue which was dissolved in H20 (70 mL), and was extracted with EtOAc (2 x 70 mL). The combined organic extracts were dried (^2804), filtered, and the solvent evaporated to give the title compound as a dark yellow solid (422 mg, 99%). Rf = 0.32 (6% MeOH in DCM). Mp = 99-102 °C. 1H NMR (DMSO-ds, 400 MHz) δ: 1.97 (3H, s, CH=C(CH3)), 5. 1 (2H, br, NH2), 6.63 (1H, t, J = 7.3, ArH), 6.76 (1H, d, J = 7.8, ArH), 7.06- 7.11 (2H, m, ArH), 7.55 (1H, s, CW=C(CH3)), 12.35 (1 H, br, C02H). 3C NMR (DMSO-d6, 100 MHz) δ: 14.23, 115.16, 115.67, 119.67, 128.00, 129.19, 129.37, 134.92, 146.90, 169.48.

Preparation 15 (£)-/\T-((5-((iert-butyldiphenyIsilyloxy)methyl)-3-hydroxy-2-methyIpyridin-4- yl)methylene)isonicotinohydrazide

A solution of 5-((fer.-butyIdiphenylsilyloxy)methyI)-3-hydroxy-2-methylpyridine-4- carbaldehyde (Imanishi I et al, Tetrahedron 2003, 59, 4873-4879) (110 mg, 0.27 mmol) and INH (37 mg, 0.27 mmol) in EtOH (8 mL) was refluxed for 90 min and then the solvent was evaporated. The resulting yellow oil was co-evaporated with Et20 to remove remaining EtOH, and the crude product was recrystallised from toluene to give the title compound as a yellow solid (123 mg, 87%). Mp = 99-101 °C. Rf = 0.33 (6% MeOH in DCM). H NMR (DMSO-de, 400 MHz) δ: 1.06 (9H, s, C(CH3)3), 2.49 (3H, s, Pyr-CH3), 5.03 (2H, s, OCH2), 7.47-7.54 (6H, m, ArH), 7.68 (2H, d, J = 7.1 , ArH), 7.89 (2H, d, J = 5.9, Pyr), 7.91 (1 H, s, Pyr), 8.89 (2H, d, J = 5.9, Pyr), 8.91 (1 H, s, HC=N), 12.15 (1 H, s, OH), 12.78 (1H, s, NH). 3C NMR (DMSO-d6, 100 MHz) δ: 18.78, 18.89, 26.62, 61.28, 119.36, 121.48, 127.95, 130.04, 130.78, 132.63, 135.03, 137.56, 139.29, 146.72, 147.72, 150.48, 150.53, 161.74.

Preparation 16

2-(((fert-ButyldimethylsilyI)oxy)methyI)-5-hydroxy-4H-pyran-4-one A solution of 5-hydroxy-2-(hydroxymethyI)-4H-pyran-4-one/kojic acid (0.5 g, 3.5 mmol) in anhydrous DCM was treated with Et3N (0.5 mL) and DMAP (0.13 g, 1.0 mmol) and stirred under argon for 10 min at 0°C. The reaction mixture was then treated with tert- butyldimethylsilylchloride (1.2 g, 8.0 mmol) and stirred for 2 h at RT. The solvent was evaporated and the residue was partitioned between DCM (30 mL) and saturated aq NH CI (30 mL). The aqueous layer was then re-extracted with DCM (30 mL), and the combined organic extracts were dried (MgS04), filtered, and the solvent evaporated. The resulting bis- silylated compound was carried forward to the next step without further purification. Thus a solution of 5-((tert-butyldimethylsilyl)oxy)-2-(((tert-butyldimethylsilyl)oxy) methyl)-4H- pyran-4-one (0.85 g, 2.3 mmol) in DMF:H20 (9:1) (40 mL) was treated with cesium carbonate and stirred for 1 h at RT. The reaction mixture was diluted with DCM (40 mL) and saturated aq NH CI (40 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the title compound as a white solid (0.52 g, 88 %). 1H NMR (500 MHz, CDCI3) δ: 0.1 1 (6H, s, Si(Ctf3)2), 0.91 (9H, s, Si(CH3)3), 4.48 (2H, s, OCH2), 6.38 (1 H, br, OH), 6.56 (1 H, s, H-3), 7.77 (1 H, s, H-6). 13C NMR (125 MHz, CDCI3) δ: -5.5, 18.1 , 25.6, 61.3, 136.8, 145.4, 168.5, 174.1.

1.1 - Synthesis of 2-hydroxycinnamoyl compounds

The compounds where the caging group is 2-hydroxycinnamoyl (leading to a coumarin upon uncaging) are prepared by coupling of a fully silylated hydroxycinnamic acid derivative with the desired chelator, either in the free form, or partially protected as a ferf-butyldiphenylsilyl ether. Coupling of the silylated cinnamic acid with the phenolic group of the chelator is achieved by treatment with oxalyl chloride, to generate an intermediate acid chloride derivative (Cevasco G, Thea S, J. Org. Chem. 1995, 60, 70-73). This is illustrated in Schemes 1 and 2. Removal of silyl ether protection from the coupled product is achieved with tetrabutylammonium fluoride and acetic acid (Hashimoto et al, Synlett 2000, 1306- 1308), as shown in Schemes 3 and 4.

Scheme 1

OR TBS-CI, imidazole OR

Scheme 2

Scheme 3

Scheme 4

1.2 - Synthesis of 2-aminocinnamoyl compounds

The compounds where the caging group is 2-aminocinnamoyl (leading to an iminocoumarin upon uncaging) are prepared by coupling of a 2-aminocinnamic acid derivative with the phenolic or enolic group of the desired chelator, either in the free form, or partially protected as a ferf-butyldiphenylsilyl ether, using ethyldimethylaminopropylcarbodiimide and 4- dimethylaminopyridine. The 2-aminocinnamic acid derivatives are prepared from the appropriate nitrobenzaldehyde, via Wittig olefination, saponification, and iron-mediated reduction of the nitro function (Li H ef al, J. Photochem. Photobiol. A 2005, 169, 289-297; Park KK, Jung JY, Heterocycles 2005, 65, 2095-2105). Removal of silyl ether protection from the coupled products, if required, is achieved with tetrabutyiammonium fluoride and acetic acid. These preparations are illustrated in Schemes 5-8.

Scheme 5

Scheme 6

Scheme 7

Scheme 8

(E)-2-((£)-(2-isonicotinoylhydrazono)methyl)phenyl-3-(2-hydroxyphenyl) acrylate (1)

Coupling A mixture of ('E)-ferf-butyldimetriylsilyl-3-(2-(ierf-butyldimethyisilyloxy)phenyl)acrylate (500 mg, 1.27 mmol) and a catalytic amount of anhydrous DMF (2 drops), was treated with 2M oxalyl chloride solution in DCM (0.8 mL, 1.59 mmol) at 0°C. The reaction mixture was stirred at this temperature under argon for 2.5 h, after which time the solvent was evaporated. A solution of SIH (256 mg, 1.06 mmol) and anhydrous pyridine (0, 1 mL, 1.1 mmol) in anhydrous DMF (2 mL) was slowly added to the residue, and the resulting mixture was stirred at RT under argon for a further 2.5 h. The solvent was then evaporated off to give an orange oil, which was dissolved in DCM (10. ml_) and washed with H20 (3 x 20 mL). The combined organic extracts were dried (MgS04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 0-4% MeOH in DCM + 0.1 % pyridine gave E)-2-(('E -(2-isonicotinoylhydrazono)methyl)phenyl-3- (2-(ieri-butyldimethylsilyloxy)phenyl) acrylate as a pale peach-coloured solid (193 mg, 36%). Rf = 0.44 (6% MeOH in DCM). Mp = 89-92 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 0.29 (6H, s, Si(CH3)2), 1.02 (9H, s, Si(CH3)3), 6.97 (1 H, d, J = 16.2, ArCH=CHC02), 7.04 (1 H, d, J = 8.2, ArH), 7.14 (1 H, t, J = 7.6, ArH), 7.34 (1 H, d, J = 7.6, ArH), 7.47 (2H, t, J = 7.1 , ArH), 7.60 (1 H, t, J = 8.2, ArH), 7.84 (2H, d, J = 6.0, Pyr), 7.99 (1 H, d, J = 7.8, ArH), 8.09 (1 H, d, J = 7.8, ArH), 8.32 (1 H, d, J = 16.2, ArCH=CHC02), 8.61 (1H, s, HC=N), 8.82 (2H, d, J = 6.0, Pyr), 12.14 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: -4.66, 17.95, 25.57, 116.31 , 119.87, 121.47, 121.95, 123.26, 124.60, 126.13, 126.47, 126.57, 127.86, 131.43, 132.71 , 140.36, 141.53, 143.13, 149.50.

Deprotection A solution of TBAF.H20 (133mg, 0.51 mmol) and glacial AcOH (26 μΐ) in anhydrous DMF (2 mL) was stirred at 0 °C under argon for 30 min. The solution was then treated with a solution of E -2-(('E)-(2-isonicotinoylhydrazono)methyl)phenyl-3-(2-(ferf- butyldimethylsilyloxy)phenyl) acrylate (70 mg, 0.14 mmol) in anhydrous DMF (2 mL), added dropwise. The reaction mixture was stirred for a further 10 min at 0 °C, after which time H20 (40 mL) was added, and the mixture extracted with Et20 (3 x 40 mL) and EtOAc (1 χ 40 mL). The combined organic extracts were dried (MgS04), filtered, and the solvent evaporated to give the crude product as a yellow oil. Purification by column chromatography on silica gel eluting with 4% MeOH in DCM + 0.1 % pyridine gave the title compound (1) as an off-white solid (46 mg, 85%). Rf = 0.41 (8% MeOH in DCM). Mp = H NMR (DMSO-d6, 500 MHz) δ: 6.90 (1 H, t, J = 7.5, ArH), 6.96-6.99 (2H, m, Ar, ArCH=CHC02), 7.30-7.33 (2H, m, ArH), 7.42 ( H, t, J = 7.6, ArH), 7.55 (1 H, t, J = 7.7, ArH), 7.74 (1 H, dd, J = 7.8, ArH), 7.80 (2H, d, J = 6.0, Pyr), 8.05 (1 H, dd, J = 7.9, ArH), 8.12 (1H, d, J = 16.1, ArCH=CHC02), 8.55 (1H, s, HON), 8.76-8.78 (2H, m, Pyr), 10.46 (1 H, s, OH), 12.14 (1 H, s, NH). 13C NMR (DMSO-d6, 125 MHz) δ: 115.60, 116.30, 119.52, 120.38, 121.58, 123.40, 125.97, 126.46, 126.63, 129.56, 131.44, 132.47, 140.36, 142.94, 143.00, 149.60, 150.30, 157.29, 161.68, 165.51. [Found (ESI+) 388.1306 [M+H]+, C22H18N304 requires 388.1297].

(£)-2-((£)-(2-isonicotinoylhydrazono)methyl)phenyl 3-(2,4-dihydroxyphenyl)acrylate (2)

Coupling A mixture of E^-ferf-butyldimethylsilyl-3-(2,4-0/s(ie -butyldimethylsilyloxy)phe acrylate (142 mg, 0.27 mmol) and a catalytic amount of anhydrous DMF (2 drops), was treated with 2M oxalyl chloride solution in DCM (0.2 mL, 0.41 mmol) at 0°C. The reaction mixture was stirred at this temperature under argon atmosphere for 2.5 h, after which time the solvent was evaporated off. A solution of SIH (52 mg, 0.22 mmol), DMAP (2 mg) and pyridine (0.1 mL, 1.1 mmol) in anhydrous DMF (0.5 mL) was slowly added to the residue, and the resulting mixture was stirred at RT under argon overnight. The solvent was then evaporated off to give an orange oil which was dissolved in DCM (10 mL) and washed with H20 (3 x 15 mL). The combined organic extracts were dried (MgS04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 0-30% acetone in DCM + 0.1 % pyridine gave (E)-2-((E -(2- isonicotinoylhydrazono)methyl)phenyl-3-(2,4- >/s(tert-butyldimethylsilyloxy)phenyl) acrylate as a white solid (42 mg, 30%). Rf = 0.75 (40% acetone in DCM). Mp = 88-91 °C. H NMR (DMSO-d6, 400 MHz) δ: 0.29 (6H, s, Si(CH3)2), 0.29 (6H, s, Si(C Y3)2), 1.01 (9H, s, Si(CH3)3), 1.01 (9H, s, Si(CH3)2), 6.41 (1 H, d, J = 2.4, ArH), 6.66 (1H, dd, J = 8.6, 2.0, ArH), 6.82 (1 H, d, J = 16.0, ArCH=CHC02), 7.32 (1 H, d, J = 8.2, ArH), 7.46 (1 H, t, J = 7.8, ArH), 7.59 (1H, t, J = 7.1 , ArH), 7.84 (2H, d, J = 6.0, Pyr), 7.90 (1 H, d, J = 9.0, ArH), 8.08 (1H, d, J = 8.0, ArH), 8.22 (1 H, d, J = 16.0, ArCH=CHC02), 8.60 (1 H, s, HC=N), 8.82 (2H, d, J = 6.0, Pyr), 12.14 (1H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: -4.50, 17.96, 18.03, 25.45 (2 signals), 110.87, 113.48, 114.53, 118^57, 121.46, 123.29, 126.03, 126.38, 126.60, 129.24, 131.40, 140.37, 141.30, 143.14, 149.60, 150.30, 155.76, 159.01 , 161.64, 165.23.

Deprotection

A solution of TBAF.H20 (114 mg, 0.36 mmol) and glacial AcOH (0.6 mL) in DMF (2 mL) was stirred at 0 °C under argon for 1 h. The reaction mixture was then treated with a solution of (E -2-(fE)-(2-isonicotinoylhydrazono)methyl)phenyl-3-(2,4-jb/s(ferf-butyldimethyl

silyloxy)phenyl) acrylate (50 mg, 0.08 mmol) in anhydrous DMF (1 mL). The reaction mixture was allowed to warm to RT and stirred for 15 min, then the solvent was evaporated off, and the resulting residue was dissolved in EtOAc (15 mL) and washed with H20 (2 x 10 mL). The organic layer was dried (MgS0 ), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 4-8% MeOH in DCM + 0.1 % pyridine gave the title compound (2) as a yellow solid (11 mg, 38%). Rf = 0.31 (10% MeOH in DCM). Mp = 183-185 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 6.38 (1 H, dd, J = 8.5, 2.2, ArH), 6.46 (1 H, d, J = 2.2, ArH), 6.77 (1 H, d, J = 16.0, ArCH=CHC02), 7.31 (1 H, d, J = 8.1 , ArH), 7.45 (1 H, t, J = 7.8, ArH), 7.59 (2H, t, J = 8.6, ArH), 7.85 (2H, d, J = 6.0, Pyr), 8.06 (2H, m, ArH, ArCW=CHC02), 8.59 (1 H, s, HC=N), 8.81 (2H, d, J = 4.6, Pyr), 10.06 (1 H, s, OH), 10.38 (1 H, s, OH), 12.17 (1 H, s, NH). 13C NMR (DMSO-d6l 100 MHz) δ 102.51 , 108.09, 111.02, 112.45, 121.55, 123.44, 125.85, 126.24, 126.73, 131.22, 131.36, 140.40, 143.1 1 , 143.42, 149.82, 150.28, 159.19, 161.70, 165.92. [Found (ESI+) 404.1228 [M+H]+, requires 404.1246]. (t 5-(hydroxymethyl)-4-((t (2-isonicotinoyto^

3-(2-hydroxyp enyl)acryIate (3)

Coupling

A mixture of (£)-te i-butyldimethylsilyl-3-(2,4-ib/s(feri-butyldimethylsilyloxy)phenyI) acrylate (235 mg, 0.60 mmol) and a catalytic amount of anhydrous DMF (2 drops) was treated with 2M oxalyl chloride solution in DCM (0.4 mL) at 0°C under an argon atmosphere. The reaction mixture was allowed to warm to RT and stirred for 3 h, after which time the solvent was evaporated off. The resulting residue was treated with a solution of (E)-N'-{(5-({tert- butyldiphenylsilyloxy) methyl)-3-hydroxy-2-methylpyridin-4-yl)methylene)

isonicotinoylhydrazide (200 mg, 0.38 mmol) and DMAP (2 mg) in anhydrous pyridine (0.1 mL) and anhydrous DMF (2 mL) and stirred at RT for 2 days. The solvent was evaporated off and the resulting residue was dissolved in DCM ( 0 mL) and washed with H20 (3 x 10 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 4% acetone in DCM + 0.1% pyridine to gave (£)-5-((te/i-butyldiphenylsilyloxy)methyl)-4-((E)-(2- isonicotinoyl hydrazono) methyl)-2-methylpyridin-3-yl-3-(2-(fert-butyldimethyl

silyloxy)phenyl)acrylate as a white solid (200 mg, 67%). Rf = 0.74 (15% acetone in DCM). Mp = 87-89 °C. 1H NMR (DMSO-d6, 400 MHz) 6: 0.29 (6H, s, Si(Ctf3)2), 1.02 (9H, s, Si(CH3)3), 1.16 (9H, s, Si(CH3)3), 2.43 (3H, s, Pyr-CH3), 5.33 (2H, s, OCH2), 6.98-7.05 (2H, m, ArH, ArCH=CHC02), 7.14 (1 H, t, J = 7.8, ArH), 7.46-7.52 (9H, m, ArH), 7.72-7.79 (6H, m ArH), 7.98 (1 H, d, J = 7.4, ArH), 8.33 ( H, d, J = 16.3, ArCH=CHC02), 8.57 (1 H, s, HC=N), 8.80 (2H, br, Pyr), 8.87 (1H, s, Pyr), 12.25 ( H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: - 4.53, 17.95, 18.93, 25.48, 26.75, 115.46, 119.88, 121.45, 121.95, 124.53, 127.98, 128.14, 129.94, 130.66, 132.86, 134.98, 142.20, 150.32, 154.44.

Deprotection A solution of TBAF.H20 (643 mg, 2.0 mmol) and AcOH (0.9 mL) in DMF (3 mL) was stirred at 0 °C for 1 h. The reaction mixture was then treated with a solution of (Έ -5-((ίθΓί- butyldiphenylsilyloxy)methyl)-4-(('E -(2-isonicotinoylhydrazono) methyl)-2-methylpyridin-3-yl- 3-(2-(teri-butyldimethylsilyloxy)phenyl)acrylate (200 mg, 0.25 mmol) in DMF (3 mL), allowed to warm to RT and stirred for a further 2 h. The solvent was evaporated and the resulting residue was dissolved in EtOAc (15 mL) and washed with H20 (2 x 10 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated off to give the crude product. Purification by column chromatography on silica gel eluting with 2-7% MeOH in DCM + 0.1 % pyridine gave the title compound (3) as a yellow solid (52 mg, 48%). Rf = 0.39 (8% MeOH in DCM). Mp = 208-212 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 2.43 (3H, s, Pyr-CH3), 4.84 (2H, d, J = 6.0, HOCH2), 5.43 (1 H, t, J = 6.0, OH), 6.95 (1 H, t, J = 7.5, ArH), 7.02-7.09 (2H, m, ArH, ArCH=CHC02), 7.37 (1 H, t, J = 7.8, ArH), 7.80 (1 H, d, J = 7.4, ArH), 7.86 (2H, d, J = 5.5, Pyr), 8.21 (1 H, d, J = 16.1 , ArCH=CHC02), 8.64 (1 H, s, Pyr), 8.66 (1H, s, HC=N), 8.83 (2H, br, Pyr), 10.52 (1 H, s, OH), 12.51 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) 5:19.02, 60.13, 114.89, 116.34, 119.54, 120.33, 121.53, 129.70, 131.53, 132.64, 134.00, 139.75, 142.37, 143.58, 146.15, 150.39, 150.72, 157.37, 162.16, 164.97. [Found (ESI+) 433. 512 [M+Hf, C2 H20 4O5 requires 433.151197],

(E)-5-(Hydroxymethyl)-4-((£)-(2-isonicotinoylhydrazono)methyl)-2-methylpyridin-3-yI- 3-(2,4-dihydroxyphenyI) acrylate (4) Coupling

A mixture of (£)-ierf-butyldimethylsilyl-3-(2,4-bis(tert-butyldimethylsilyloxy)phenyl) acrylate (565 mg, 1.06 mmol) and a catalytic amount of anhydrous DMF (3 drops) was treated with 2M oxalyl chloride solution in DCM (0.8 mL) at 0°C under argon. The reaction mixture was allowed to warm to RT and stirred for 3 h, after which time the solvent was evaporated. The resulting residue was treated with a solution of (E)-N'-((5-((tert-butyldiphenylsilyloxy)methyl)- 3-hydroxy-2-methylpyridin-4-yl)methylene)isonico tinoylhydrazide (400 mg, 0.76 mmol) and DMAP (2 mg) in anhydrous pyridine (0.1 mL) and anhydrous DMF (5 mL) and stirred at RT for 3 days. The solvent was evaporated and the resulting residue was dissolved in DCM (10 mL) and washed with saturated aq NH CI solution (2 10 mL) and H20 (3 x 10 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 4% acetone in DCM + 0.1 % pyridine gave (£)-5-((fert-butyldiphenylsilyloxy)methyl)-4-((£)-(2- isonicotinoylhydrazono)methyl)-2-methyl pyridin-3-yI-3-(2,4~bis(ferf-butyl dimethylsilyloxy) phenyl) acrylate as a yellow solid (347 mg, 50%). Rf = 0.27 (30% EtOAc in petroleum ether). Mp = 84-89 °C. H NMR (DMSO-d6, 400 MHz) δ: 0.29 (12H, s, 2 x Si(Ctf3)2), 1.01 (18H, s, 2 x Si(CH3)3), 1.16 (9H, s, Si(CH3)3), 2.42 (3H, s, Pyr-CH3), 5.34 (2H, s, OCH2), 6.42 (1 H, d, J = 2.3, ArH), 6.66 (1 H, dd, J = 8.4, 1.9, ArH), 6.85 (1 H, d, J = 16.2, ArCH=CWC02), 7.48- 7.50 (8H, m, ArH), 7.72-7.79 (6H, m, ArH), 7.90 ( H, d, J = 8.2, ArH), 8.25 (1 H, d, J = 16.2, ArCH=CHC02), 8.56 (1 H, s, HC=N), 8.81 (2H, br, Pyr), 8.88 (1 H, s, ArH), 12.25 (1 H, s, NH). 13C NMR (DMSO-de, 100 MHz) δ -4.53, 18.91 , 24.07, 25.46, 25.78, 26.52, 62.85, 1 0.88, 112.92, 114.55, 121.47, 127.98, 129.52, 129.92, 134.97, 141.97, 142.08, 144.24, 150.32.

Deprotection

A solution of TBAF'3H20 (345 mg, 1.10 mmol) and glacial AcOH (50 μ!_) in THF (7.5 mL) was treated with f£ -5-((fe/i-butyldiphenylsilyloxy)methyl)-4-(('£;)-(2-isonicotinoyl hydrazono) methyl)-2-methylpyridin-3-yl 3-(2,4-b/s(ferf-butyldimethylsilyloxy) phenyl)acrylate (200 mg, 0.22 mmol). The reaction mixture was stirred at RT for 48 h, after which DOWEX 50WX8- 400 ion-exchange resin (770 mg), CaC03 (254 mg) and MeOH (8 mL) were added, and the mixture stirred for an additional 2 h at RT. The ion-exchange resin and other insoluble materials were removed by filtering the reaction mixture through celite, and the celite pad was washed thoroughly with EtOAc and MeOH. The combined filtrates were evaporated to give the crude product, which was purified by column chromatography on silica gel eluting with 6-10% MeOH in DCM + 0.1% pyridine to give the title compound (4) as a yellow solid (30 mg, 30%). Rf = 0.26 (10% MeOH in DCM). Mp = 210-212 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 2.41 (3H, s, Pyr-Me), 4.84 (2H, d, J = 6.2 HOCH2), 5.42 (1 H, t, J = 6.2, OH), 6.39 (1 H, dd, J = 8.5, 2.3, ArH), 6.46 (1 H, d, J = 2.3, ArH), 6.81 (1 H, d, J = 16.0, ArCH=CHC02), 7.61 (1 H, d, J = 8.5, ArH), 7.87 (2H, d, J = 4.5, Pyr), 8.11 (1 H, d, J = 16.0, ArCW=CHC02), 8.63 (1H, s, Pyr), 8.64 (1H, s, HC=N), 8.84 ( H, br, Pyr), 10.14 (1H, br, OH), 10.44 (1H, br, OH), 12.55 (1 H, br, NH). 13C NMR (DMSO-d6, 100 MHz) δ: 19.01 , 60.21 , 102.51 , 108.16, 110.27, 112.38, 121.75, 131.44, 131.62, 133.90, 142.48, 144.10, 145.96, 150.39, 159.36, 161.90, 165.39. [Found (ESI+) 447.1324 [M+Hf, C23H19N4Oe requires 447.1305].

(E)-2-((£)-(2-isonicotinoylhydrazono)methyl)phenyl-3-(2-amino-4,5-dimethoxyphenyI) - 2-methyl acrylate (5)

A solution of (£)-3-(2-Amino-4,5-dimethoxyphenyl)-2-methylacrylic acid (150 mg, 0.63 mmol) in anhydrous DMF (10 mL) was cooled to 0 °C under nitrogen and was treated with EDC-HCI (121 mg, 0.63 mmol) and DMAP (77 mg, 0.63 mmol). After 5 min, SIH (152 mg, 0.63 mmol) was added and the reaction was stirred for a further 4 days at RT. The solvent was evaporated and the crude product was purified by column chromatography on silica gel, eluting with 2% MeOH in DCM + 0.1% pyridine. This gave the title compound (5) as an orange solid (212 mg, 73%). Rf = 0.42 (5% MeOH in DCM). 1H NMR (DMSO-d6, 400 MHz) δ: 2.18 (3H, s, CH=C(CH3)), 3.66 (3H, s, OCH3), 3.72 (3H, s, OCH3), 5.13 (2H, s, NH2), 6.43 (1 H, s, ArH), 6.81 (1 H, s, ArH), 6.91-6.94 (1 H, m, ArH), 7.25 (1 H, d, J = 8.0, ArH), 7.30 (1 H, t, J = 7.7, ArH), 7.37 (1H, t, J = 7.6, ArH), 7.52 (1 H, t, J = 7.9, ArH), 7.58 (1 H, d, J = 7.6, ArH), 7.87 (2H, m, ArH), 8.00 (1H, d, J = 7.8, ArH), 8.55 (1 H, s, CH=C(CH3)), 8.67 (1H, s, HC=N), 12.08 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: 14.60, 55.19, 56.53, 100.05, 110.15, 114.15, 116.44, 118.67, 1 19.41 , 122.14, 123.49, 126.16, 126.38, 126.70, 129.26, 131.26, 131.70, 137.82, 139.97, 143.62, 143.71 , 149.07, 150.08, 151.64, 157.48, 161.72, 166.90. [Found (ESI+) 461.1815 [M+H+], C25H24N405 requires 461.1825].

(EJ-Z-iiEJ-^-isonicotinoylhydrazonoJmethylJphenyl-S-ie-aminobenzot lII ,3]dioxol-5- yl)-2-methylacrylate (6)

A solution of (E)-3-(6-aminobenzo[d][1 ,3]dioxol-5-yl)-2-methylacryIic acid (136 mg, 0.62 mmol) in anhydrous DMF (8 mL), was cooled to 0 °C under argon and was treated with EDC.HCI (120 mg, 0.62 mmol) and DMAP (76 mg, 0.62 mmol). The mixture was stirred for 10 min, then a solution of SIH (100 mg, 0.41 mmol) and DIPEA (71 μί., 0.41 mmol) in anhydrous DMF (2 mL) was added. The resulting mixture was stirred at 30°C for 2 days, then the solvent was evaporated. The resulting residue was dissolved in DCM (10 mL) and was washed with saturated aq NH4CI solution (3 x 30 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated. Purification by column chromatography on silica gel, eluting with 2-4% MeOH in DCM + 0.1% pyridine gave the title compound (6) as an orange-yellow solid (130 mg, 71%). Rf = 0.39 (8% MeOH in DCM). Mp = 109-1 11 °C. H NMR (DMSO-ds, 400 MHz) δ: 2.22 (3H, d, J = 1.1 , CH=C(CH3)), 5.36 (2H, s, NH2), 5.82 (2H, s, OCH20), 6.47 (1 H, s, ArH), 6.88 (1 H, s, ArH), 7.34 (1 H, d, J = 8.2, ArH), 7.46 (1 H, t, J = 7.5, ArH), 7.60 (1 H, td, J = 8.1, 1.7, ArH), 7.86 (2H, d, J = 6.0, Pyr), 7.90 (1 H, d, J = 1.1 , CH=C(CH3), 8.07 (1 H, dd, J = 7.9, 1.6, ArH), 8.61 (1 H, s, CH=N), 8.84 (2H, d, J = 6.0, Pyr), 12.19 (1 H, s, NH). [Found (ESI+) 445.1471 [M+H]+, C24H21N405 requires 445.1506], f£ 5-(Hydroxymethyl)-4-((E (2-isonicotinoyIhydrazono)methyl)-2-methyIpyridin-3-yI 3- (6-aminobenzo[d][1 ,3]dioxol-5-yl)acrylate (7)

Coupling

A solution of (£)-3-(6-aminobenzo[ /][1 ,3]dioxol-5-yl)-2-methylacrylic acid (400 mg, 1.80 mmol) in anhydrous DMF (15 mL), was cooled to 0 °C under argon and treated with EDC.HCI (340 mg, 1.80 mmol) and DMAP (220 mg, 1.80 mmol). The mixture was stirred for 10 min, then a solution of (^-^-((S-iiierf-butyldiphenylsilyloxyJmethylJ-S-hydroxy^- methylpyridin-4-yl)methylene)isonicotinohydrazide (640 mg, 1.22 mmol) and DIPEA (0.2 mL, 1.52 mmol) in a solution of anhydrous DMF (5 mL) was added. The resulting mixture was allowed to return to RT and stirred overnight, then the solvent was evaporated. The resulting residue was dissolved in DCM (30 mL) and washed with saturated aq NH4CI solution (3 χ 30 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated. Purification by column chromatography on silica gel, eluting with 4-20% acetone in DCM + 0.1 % pyridine gave (E)-5~((£erf-butyldiphenyisilyloxy) methyl)-4-((£)-(2- isonicotinoyl hydrazono)methyl)-2-methylpyridin-3-yl 3-(6-amino benzo[d][1 ,3]dioxoI-5-yl)-2- methylacrylate as a yellow solid (230 mg, 56%). Rf = 0.72 (20% acetone in DC ). 1H N R (DMSO-d6, 400 MHz) mixture of rotamers δ: 1.01 (9H, s, Si(CH3)3), 2.07-2.36 (4H, m, Pyr- CH3, CH=C(CH3)), 5.24-5.28 (2H, m, OCH2), 5.92-6.08 (2H, m, OCH20), 6.42 (1 H, s, ArH), 6.64-8.52 (16H, m, CH=C(CH3), ArH, Py, CH=N), 8.76 (2H, s, Py), 12.23 (1 H, s, NH). 13C NMR (DMSO-ds, 100 MHz) mixture of rotamers δ: 15.13, 19.20, 20.82, 26.74, 27.78, 64.88, 79.16, 100.653, 100.89, 101.53, 108.12, 110.48, 117.91, 121.48, 127.98, 129.94, 130.83, 132.87, 134.98, 138.02, 140.01 , 143.26, 146.51 , 148.85, 150.36, 166.06, 170.93.

Deprotection A solution of TBAF-3H20 (600 mg, 1.94 mmol) and AcOH (98 μΙ_) in THF (15 mL) was treated with (JE)-5-((ferf~butyldiphenylsilyloxy) methyl)-4-((£)-(2-isonicotinoyl

hydrazono)methyl)-2-methylpyridin-3-yl 3-(6-aminobenzo[ ][1 ,3]dioxol-5-yl)-2-methyl acrylate (470 mg, 0.65 mmol). The reaction mixture was stirred at RT overnight, then the solvent was evaporated and the resulting residue was dissolved in EtOAc and was washed with H20 (2 x 100 mL), and saturated aq NH4CI solution (50 mL). The organic layer was dried (Na2S04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 3-9% MeOH in DCM + 0.1 % pyridine gave the title compound (7) as an orange solid (201 mg, 63%). Rf = 0.14 (4% MeOH in DCM). Mp = 157- 62 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 2.24 (3H, s, CH=C(CH3)), 2.44 (3H, s, Pyr-Me), 4.82 (2H, d, J = 6.1 , HOCH2), 5.31 (2H, s, NH2), 5.44 ( H, t, J = 6.1 , OH), 5.98 (2H, s, OCH20), 6.48 (1 H, s, ArH), 6.90 (1 H, s, ArH), 7.89 (2H, d, J = 5.5, Pyr), 7.92 (1 H, s,

CH=C(CH3)), 8.61 ( H, s, Pyr), 8.66 (1 H, s, HC=N), 8.85 (2H, br, Pyr), 12.49 (1 H, br s, NH). 13C NMR (DMSO-d6, 100 MHz) 6: 14.57, 19.18, 59.95, 96.89, 100.64, 108.13, 110.54, 121.57, 122.05, 131.57, 133.95, 138.11 , 138.49, 139.75, 142.75, 143.84, 144.74, 146.00, 149.33, 150.40, 151.18, 162.12, 166.26. [Found (ESI+) 490.1732 [M+H]+, C25H23N506, requires 490.1727]. E 5-(hydroxymethyl)-4-(('£ ('2-isonicotinoyI hydrazono)methyI)-2-methylpyridin-3-yI 3-(2-amino-4,5-dimethoxyphenyI)acrylate (10)

Coupling A solution of (E)-3-(2-amino-4,5-dimethoxyphenyl)-2-methylacrylic acid (418 mg, 2.30 mmol) in anhydrous DMF (15 mL), was cooled 0 °C under argon and was treated with EDC.HC! (330 mg, 2.30 mmol) and DMAP (210 mg, 2.30 mmol). The mixture was stirred for 10 min, then a solution of (E)-W-((5-((ferf-butyldiphenylsilyloxy)methyl)-3-hydroxy-2-methylpyridin-4- yl)methylene)isonicotinohydrazide (600 mg, 1.52 mmol) and DIPEA (0.2 mL, 1.52 mmol) in anhydrous DMF (5 mL) was added The resulting mixture was allowed to return to RT and stirred overnight, then the solvent was evaporated. The resulting residue was dissolved in DCM (50 mL) and washed with saturated aq NH4CI solution (3 χ 50 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated. Purification by column chromatography on silica gel, eluting with 4-20% acetone in DCM gave (E)-5-((tert- butyldiphenylsilyloxy) methyl)-4-((E)-(2-isonicotinoyl hydrazono)methyl)-2-methylpyridin-3-yl 3-(2-amino-4,5-dimethoxyphenyI)acrylate as a yellow solid (604 mg, 53%). Rf = 0.76 (20% acetone in DCM). 1H NMR (DMSO-d6) 400 MHz) mixture of rotamers δ: 1.15-1.20 (9H, m, Si(CH3)3), 2.15-2.30 (6H, m, CH=C(CH3), Pyr-Me), 3.73-3.84 (6H, m, 2 x OMe), 5.22-5.31 (2H, m, OCH2), 6.44-6.51 (1 H, m, ArH), 7.14-8.58 (15H, m, CW=C(CH3), ArH, Py, CH=N), 8.82 (3H, s, Py), 12.26 (1 H, s, NH).

Deprotection

A solution of TBAF-3H20 (378 mg, 1.20 mmol) and AcOH (55 uL) in THF (1 1 mL) was treated with E)-5-((£erf-butyldiphenylsilyloxy) methyl)-4-((£)-(2-isonicotinoyl hydrazono)methyl)-2-methylpyridin-3-yl 3-(2-amino-4,5-dimethoxyphenyl)acrylate (300 mg, 0.40 mmol). The reaction mixture was stirred at RT overnight, then the solvent was evaporated and the resulting residue was dissolved in EtOAc and was washed with H20 (2 x 60 mL), and saturated aq NH CI solution (30 mL). The organic layer was dried (Na2S04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 3-9% MeOH in DCM + 0.1 % pyridine to give the title compound (10) as a yellow solid (60 mg, 50%). Rf = 0.19 (4% MeOH in DCM). Mp = 189-193 °C. 1H NMR (DMSO-d6, 400 MHz) δ: 2.27 (3H, s, CH=C(CH3)), 2.45 (3H, s, PyrMe), 3.73 (3H, s, OMe), 3.79 (3H, s, OMe), 4.82 (2H, d, J = 6.0, HOCH2), 5.21 (2H, br, NH2), 5.45 (1 H, t, J = 6.0, OH), 6.50 (1 H, s, ArH), 6.91 (1 H, s, ArH), 7.87 (2H, d, J = 5.2, Pyr), 7.96 (1 H, s, ArH), 8.62 (1H, s, HC=N), 8.67 (1 H, s, Pyr), 8.86 (2H, d, J = 5.2, Pyr), 12.49 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: 14.63, 19.19, 55.16, 56.42 , 59.94, 100.00, 110.11 , 1 14.06, 121.53, 121.69, 131.55, 133.95, 138.16, 139.78, 139.96, 142.74, 143.79, 143.85, 145.99, 150.40, 151.20, 151.66, 162.12, 166.33. [Found (ESI+) 506.2058 [M+H]+, C26H28N5Ob requires 506.2040]. (E)-5-(hydroxymethyl)-4-((E)-(2-isonicotinoylhydrazono)-methyl)-2-methylpyridin-3-yl 3-(2-amino-4-(trif luoromethyl)phenyl)acryIate (11 )

Coupling

A solution of (£)-2-methyl-3-(2-nitro-4-(trifluoromethyl)phenyl)acrylic acid (280 mg, 1.14 mmol) in anhydrous DMF (8 mL) was cooled to 0 °C under argon and was treated with EDC.HCl (220 mg, 1.14 mmol) and DMAP (140 mg, 1.14 mmol). The mixture was stirred for 10 min, then a solution of (£)-W-((5-((ierf-butyldiphenylsilyloxy)methyl)-3-hydroxy-2- methylpyridin-4-yl)methyIene)isonicotinohydrazide (400 mg, 0.76 mmol) and DIPEA (0.15 mL) in anhydrous DMF (7 mL) was added. The resulting mixture was stirred at RT overnight, then the solvent was evaporated. The resulting residue was dissolved in DCM (40 mL) and washed with saturated aq NH4CI solution (2 χ 40 mL). The organic layer was dried (MgS04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 6-20% acetone in DCM + 0.1 % pyridine to gave (E)-5-((terf-butyldiphenylsilyloxy) methyl)-4-((E)-(2-isonicotinoyl hydrazono) methyl)-2- methyl pyridin-3-yl 3-(2-amino-4-(trifluoromethyl)phenyl)acrylate as a pale yellow solid (240 mg, 42%). Rf = 0.46 (20% acetone in DCM). 1H NMR (DMSO-d6, 400 MHz) δ: 1.14 (9H, s, Si(CH3)3), 2.20 (3H, s, CH=C(Ctf3), 2.49 (3H, s, Pyr-Me), 5.27 (2H, s, CH2), 5.84 (2H, s, NHZ), 6.95 (1H, d, J = 8.2, ArH), 7.13 ( 1H, s, ArH), 7.43 (1 H, d, J = 7.1 , Ar), 7.49-7.50 (6H, m, ArH), 7.73 (4H, d, J = 6.5, ArH), 7.82 (2H, d, J = 4.4, Pyr), 7.88 (1 H, s, CH=C(CH3)), 8.60 (1 H, s, HC=N), 8.76 (1 H, s, Pyr), 8.84 (2H, d, J = 4.4, Pyr), 12.27 (1 H, s, NH). 3C NMR (DMSO-d6, 100 MHz) δ: 14.50, 18.89, 19.21 , 26.71 , 62.44, 111.36, 111.29, 121.51 , 125.61 , 127.99, 129.71 , 130.60, 132.79, 134.99, 136.94, 142.32, 147.68, 150.38, 162.85, 165.57.

Deprotection

A solution of TBAF-3H20 (290 mg, 0.92 mmol) and AcOH (47 pL) in THF (5 mL) was treated with (£)-5-((ferf-butyldiphenylsilyloxy) methyl)-4-((£)-(2-isonicotinoyl hydrazono) methyl)-2- methylpyridin-3-yl 3-(2-amino-4-(trifluoromethyl)phenyl)acrylate (230 mg, 0.31 mmol). The reaction mixture was stirred at RT overnight, then the solvent was evaporated and the resulting residue was dissolved in EtOAc and was washed with H20 (3 x 40 mL), and saturated aq NH4CI solution (40 mL). The organic layer was dried (Na2S0 ), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 3-10% MeOH in DCM + 0.1 % pyridine gave the title compound (11) as a yellow solid (85 mg, 53%). Rf = 0.41 (10% MeOH in DCM). Mp = 220-222 °C. H NMR (DMSO-d6, 400 MHz) δ: 2.16 (3H, s, CH=C(CH3), 2.43 (3H, s, Pyr-Me), 4.76 (2H, d, J = 6.0, HOCH2), 5.45 (1 H, t, J = 6.0, OH), 5.82 (2H, s, NH2), 6.91 (1 H, d, J = 7.9, ArH), 7.08 (1 H, s, ArH), 7.39 (1 H, d, J = 7.9, ArH), 7.83 (1 H, s, CH=C(CH3), 7.84 (2H, d, J = 5.2, Pyr), 8.57 (1 H, s, HC=N), 8.64 (1H, s, Pyr), 8.82 (2H, d, J = 5.2, Pyr), 12.44 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: 14.55, 19.21, 59.69, 111.17, 111.32, 121.57, 122.20, 125.37, 128.00, 130.64, 131.40, 134.12, 136.85, 139.77, 142.74, 143.19, 146.26 , 147.67, 150.43, 151.26, 162.05, 165.62. [Found (ESI+) 514.1706 [M+Hf, C25H23F3N504 requires 514.1702]. (E)-5-(hydroxymethyl)-4-((E (2-isonicotinoylhyd 3- (2-aminophenyl)acrylate (13)

Coupling

A solution of (£)-2-methyl-3-(2-nitrophenyl)acrylic acid (150 mg, 0.85 mmoi) in anhydrous D F (5 mL), was cooled to 0 °C under argon and was treated with EDC.HCI (163 mg, 0.85 mmol) and DMAP (104 mg, 0.85 mmol). The mixture was stirred for 10 min, then a solution of (E)-/V-((5-((te f-butyldiphenylsilyloxy)methyl)-3-hydroxy-2-methylpyridin-4-yl) methylene)isonicotinohydrazide (320 mg, 0.61 mmol) and DIPEA (0.1 mL). in anhydrous DMF (5 mL) was added. The resulting mixture was stirred at RT overnight, then the solvent was evaporated. The resulting residue was dissolved in DCM (30 mL) and was washed with H20 (40 mL) and saturated aq NH4CI solution (2 χ 30 mL). The organic layer was dried (Na2S0 ), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 5-30% Acetone in DCM + 0.1 % pyridine gave (E)-5-((£erf-butyldiphenylsilyloxy) methyl)-4-((£)-(2-isonicotinoyl hydrazono) methyl)-2- methylpyridin-3-yl 3-(2-aminophenyl)acrylate as a pale yellow solid (341 mg, 82%). Rf = 0.34 (20% acetone in DCM). Mp = 81-84 °C. 1H NMR (DMSO-d6, 400 MHz) S 1.15 (9H, s, Si(CH3)3), 2.22 (3H, s, CH=C(CW3)), 2.48 (3H, s, Pyr-Me), 5.30 (2H, s, OCH2), 5.39 (2H, s, NH2), 6.70 (1 H, t, J = 7.4, ArH), 6.82 (1 H, d, J = 7.8, ArH), 7.16 (1 H, t, J = 7.4, ArH), 7.26 ( H, d, J = 7.8, ArH), 7.46-7.54 (6H, m, ArH), 7.73 (4H, d, J = 6.5, ArH), 7.82 (2H, d, J = 5.0, Pyr), 7.95 (1 H, s, CH=C(CH3)), 8.60 (1 H, s, N=CH), 8.83 (2H, d, J = 5.0, Pyr), 12.28 (1 H, s, NH). 13C NMR (DMSO-d6, 100 MHz) δ: 14.51 , 18.90, 19.21 , 26.73, 62.64, 115.51 , 1 15.74, 1 18.72, 121.53, 122.88, 125.07, 126.88, 127.98, 129.65, 129.95, 130.66, 132.84, 134.99, 138.53, 140.04, 142.36, 143.54, 144.35, 147.52, 150.36, 151.06, 161.75, 165.98.

Deprotection A solution of TBAF*3H20 (270 mg, 0.86 mmol) and AcOH (42 pL) in THF (8 mL) was treated with (£)-5-((fe/f-butyldiphenylsiIyloxy) methyl)-4-((£)-(2-isonicotinoyl hydrazono) methyl)-2- methylpyridin-3-yl 3-(2-aminophenyl)acrylate (200 mg, 0.29 mmol). The reaction mixture was stirred at RT overnight, then the solvent was evaporated and the resulting residue was dissolved in EtOAc and was washed with H20 (40 mL), and saturated aq NH CI solution (40 mL). The organic layer was dried (Na2S04), filtered, and the solvent evaporated to give the crude product. Purification by column chromatography on silica gel eluting with 3-6% MeOH in DCM + 0.1 % pyridine gave the title compound (13) as a light yellow solid (69 mg, 53%). Rf = 0.47 (8% MeOH in DCM). Mp = 269-271 °C. 1H NMR (DMSO-dB, 400 MHz) δ: 2.22 (3H, s, CH=C(CH3), 2.46 (3H, s, Pyr-Me), 4.82 (2H, d, J= 5.9, HOCH2), 5.40 (2H, s, NH2), 5.46 (1 H, t, J = 5.9, OH), 6.69 (1 H, t, J = 7.4, ArH), 6.82 (1 H, d, J = 7.8, ArH), 7.16 (1 H, t, J = 7.4, ArH), 7.27 (1 H, d, J = 7.8, ArH), 7.89 (2H, d, J = 5.0, Pyr), 7.95 (1 H, s, CH=C(CH3), 8.62 (1 H, s, N=CH), 8.69 (1 H, s, Pyr), 8.86 (1 H, d, J = 5.0, Pyr), 12.50 (1 H, s, NH). 13C NMR (DMSO-dB, 100 MHz) δ: 14.52, 19.18, 59.85, 1 15.48, 1 15.73, 118.78, 121.56, 125.22, 129.66, 130.10, 131.52, 134.02, 138.44, 139.77, 142.71 , 143.57, 146.12, 147.47, 150.40, 151.19, 162.09, 166.01. [Found (ESI+) 446.1859 [M+H]+, C^H^ sC requires 446. 828].

(t 6-(hydroxymethyl)-4-oxo-4H-pyran~3-yl 3-(6-aminobenzo[d][1 ,3]dioxol-5-yI)-2- methylacrylate (27)

Coupling A solution of O-S-ie-aminobenzofdlll .S^ioxol-S-y ^-methylacrylic acid (120 mg, 0.54 mmol) in anhydrous DMF (7 mL) was treated with EDC.HCI ( 04 mg, 0.54 mmol) and DMAP (66 mg, 0.54 mmol) and stirred under argon for 10 min at 0°C. A solution of 2-(((tert- butyldimethylsilyl)oxy)methyl)-5-hydroxy-4H-pyran-4-one (92 mg, 0.36 mmol) and DIPEA (62 L, 0.36 mmol) in anhydrous DIVIF (3 mL) was then added and the mixture was stirred under argon for 48 h at RT. The solvent was evaporated and the residue was partitioned between DC (15 mL) and saturated aq NH4CI (15 mL). The aqueous layer was re-extracted with DCM (15 mL) and the combined organic layers were dried (MgS04), filtered, and the solvent evaporated. Purification by column chromatography on silica gel eluting with 5% MeOH in DCM gave E -6-(((tert-butyldimethylsilyl)oxy)methyl)-4-oxo-4H-pyran-3-yl 3-(6- aminobenzo[d][1 ,3]dioxol-5-yl)-2-methylacrylate as a colourless oil (92 mg, 55 %). 1H NMR (500 MHz, CDCI3) δ: 0.12 (6H, s, Si(CH3)2)), 0.93 (9H, s, Si(Ctf3)3), 2.21 (3H, s, CH=C(CH3)), 3.70 (2H, br, NH2), 4.49 (2H, s, OCH2), 5.88 (2H, s, OCH20), 6.29 (1 H, s, ArH), 6.56 (1 H, s, ArH), 6.70 (1 H, s, H-3), 7.80 (1 H, s, CH=C(CH3)), 7.88 (1 H, s, H-6). 13C NMR (125 MHz, CDCI3) δ: -5.5, 14.3, 18.1 , 25.6, 61.0, 97.6, 100.9, 108.5, 112.6, 112.8, 125.4, 137.6, 140.2, 141.2, 141.4, 147.3, 149.2, 165.5, 167.6, 172.9.

Deprotection

A solution of TBAF.H20 (100 mg, 0.31 mmol), AcOH (35 μί) and THF (2 mL) were stirred for 2 min at RT. A solution of fE -6-(((tert-butyldimethylsilyl)oxy)methyl)-4-oxo-4H-pyran-3-yl 3- (6-aminobenzo[dj[1,3]dioxol-5-yl)-2-methyiacrylate (48 mg, 0.1 mmol) in THF (1 mL) was then added and the reaction was stirred for 2 h further at RT. The solvent was evaporated, and the residue was partitioned between EtOAc (15 mL) and saturated aq NH4CI (15 mL). The aqueous layer was re-extracted with EtOAc (15 mL) and the combined organic layers were dried (MgS04), filtered, and the solvent evaporated.. Purification by column chromatography on silica gel eluting with 5% MeOH in DCM gave the title compound (27) as a yellow solid (23 mg, 62 %). 1H NMR (500 MHz, CDCI3) δ: 2,07 (3H,s, CH=C(CW3)), 4.36- 4.37 (2H, m, OCH2), 5.15 (2H, br, NH2), 5.91 (2H, s, OCH20), 6.40 (1 H, s, ArH), 6.44 (1 H, s, ArH), 6.78 (1 H, s, H-3), 7.71 (1H, s, CH=C(CH3)), 8.48 (1H, s, H-6). 13C NMR (125 MHz, CDCI3) δ: 16.3, 59.2, 96.9, 100.5, 108.5, 110.5, 112.0, 121.8, 137.9, 138.4, 140.7, 144.6, 148.8, 149.2, 165.3, 169.2, 172.0. [Found (ES+) 368.0747 [M + Naf, C17H15NNa07 requires 368.0746].

(£)-6-(hydroxymethyI)-4-oxo-4H-pyran-3-yl 3-(2-amino-4,5-dimethoxyphenyl)-2- methylacrylate (28)

Coupling A solution of (E)-3-(2-Amino-4,5-dimethoxyphenyl)-2-methylacrylic acid (200 mg, 0.84 mmol) in anhydrous DMF (7 mL) was treated with EDC.HCI (160 mg, 0.84 mmol) and DMAP (102 mg, 0.84 mmol) and stirred under argon for 10 min at 0°C. A solution of 2-{((tert- butyldimethylsilyl)oxy)methyl)-5-hydroxy-4H-pyran-4-one (143 mg, 0.56 mmol) and DIPEA (97 pL, 0.56 mmol) in anhydrous DMF (3 mL) was then added and the mixture was then stirred under argon for 24 h at RT. The solvent was evaporated, and the residue was partitioned between DCM (15 mL) and saturated aq NH4CI (15 mL). The aqueous layer was re-extracted with DCM (15 mL) and the combined organic layers were dried (MgS0 ), filtered, and the solvent evaporated. Purification by column chromatography on silica gel, eluting with 5% MeOH in DCM gave (£)-6-(((ieri-butyldimethylsilyl)oxy)methyl)-4-oxo-4H- pyran-3-yl 3-(2-amino-4,5-dimethoxyphenyl)-2-methylacrylate as a yellow solid (108 mg, 40 %), mp 105-106 °C. 1H NMR (500 MHz, CDCI3) δ: 0.19 (6H, s, Si(CW3)2), 0.93 (9 H, s, Si(CH3)2), 2.15 (3H,s, CH=C(CH3)), 3.66 (2H, s, NH2), 3.81 (3H, s, OCH3), 3.85 (3H, s, OCH3), 4.50 (2H, s, OCH2), 6.29 (1 H, s, ArH), 6.57 (1 H, s, ArH), 6.76 (1 H, s, H-3), 7.85 (1 H, s, CA7=C(CH3)), 7.88 (1 H, s, H-6). 13C NMR (125 MHz, CDCI3) δ: -5.4, 14.5, 18.2, 25.7, 26.8, 30.9, 55.7, 56.6, 61.0, 100.2, 112.1 , 112.8, 1 13.2, 125.2, 137.8, 140.1 , 141.4, 141.6, 147.4, 151.1 , 165.6, 167.8, 173.0.

Deprotection

A solution of TBAF.H20 (215 mg, 0.68 mmol), glacial ACOH (32 pL) and THF (5 mL) were stirred for 2 min at RT. A solution of (£)-6-(((fe i-butyldimethylsilyl)oxy)methyl)-4-oxo-4H- pyran-3-yl-3-(2-amino-4,5-dimethoxyphenyl)-2-methylacrylate (108 mg, 0.22 mmol) in THF (1 mL) was then added and the reaction was stirred for 1 h at RT. The solvent was evaporated and the residue was partitioned between EtOAc (15 mL) and saturated aq NH4CI (15 mL). The aqueous layer was re-extracted with EtOAc (15 mL) and the combined organic layers were dried (MgS04), filtered, and the solvent evaporated. Purification by column chromatography on silica gel 5% MeOH in DCM gave the title compound (28) as a yellow solid (47 mg, 57 %), mp 154-155 °C. 1H NMR (500 MHz, CDCI3) δ: 2.16 (3H,s, CH=C(CH3)), 3.72 (2H, br, NH2), 3.81 (3H, s, OCH3), 3.86 (3H, s, OCH3), 4.52 (2H, s, OCH2), 6.30 (1H, s, ArH), 6.58 (1 H, s, ArH), 6.76 (1 H, s, H-3), 7.86 (1 H, s, CH=C(CH3)), 7.93 (1 H, s, H-6). 3C NMR (125 MHz, CDCI3) δ: 14.5, 55.7, 56.6, 60.9, 77.2, 100.3, 1 12.0, 113 3, 124.9, 138.1 , 140.3, 141.4, 141.6, 147.8, 151.2, 165.6, 167.4, 173.1. [Found (ES+) 384.1059 [M+Na]+, C18HigNNa07 requires 384.1054].

2. UVA Uncaging, ROS Production, Cell Impact and Toxicity Studies

2.1 - Materials 2.1.1 - Cell Cultures

Cell culture materials were obtained from Gibco (Germany) except for Foetal Bovine Serum (FBS) that was purchased from PAA Laboratories (Austria). All chemicals were from Sigma- Aldrich Chemical (Poole, UK) except Annexin-V-FLUOS that was supplied from Roche (Mannheim, Germany), CM-H2DCFDA [ 5~(and-6)-carboxy methyl-20,70- dichlorodihydrofluorescein diacetate] from Invitrogen (Paiseley, Scotland), anti-BrdU primary antibody from Beckton Dickinson (Oxford, UK) and FITC-conjugated rabbit anti mouse secondary antibody F(ab')2 from DAKO UK Ltd (Ely, Cambridge Shire, UK). MilliQ water used to prepare phosphate buffered saline (PBS) and other stock solutions were issued from a Millipore purification system (MilliQ cartridge: Millipore, Bedford, MA) in order to minimize the presence of trace elements such as transition metals.

Cell lines:

- FEK4: Human primary skin fibroblasts derived from a newborn foreskin (in the laboratory of Prof. R.M. Tyrrell (University of Bath)). The FEK4 fibroblasts are passage-dependent and in this study were used between passages 11 to 16. - HaCaT: Human spontaneously immortalised skin keratinocyte cell line derived from an adult back. This cell line maintains fully epidermal differentiation capacity, but remains non- tumorigenic (see Boukamp P, Petrussevska RT, Breitkreutz D, Hornung J, Markham A, Fusenig NE. J Cell Biol. 1988, 106:761-71).

Monolayer Cell Culture: - FEK4 cells were cultured in growth medium composed of 15% FBS-EMEM (Earle's modified minimum essential medium) supplemented with 0.25% sodium bicarbonate, 2 mM L-glutamine and 50 lU/ml of each of penicillin/ streptomycin (P/S). - HaCaT cells were cultured in growth medium composed of 10% FBS-DMEM (high-glucose Dulbecco's modified eagles medium) supplemented with 50 lU/ml P/S.

Both FEK4 and HaCaT cells were passaged by trypsinisation once a week.

For BrdU and Annexin V/propidium iodide assays, HaCaT cells were seeded at a density of 2x104 cells in 35 cm plate containing 2 ml of media and grown for 2 days to reach 30% confluency on the day of iron chelator treatment. For both ROS and Annexin V/proipidium assays, FEK4 cells were seeded at a density of 8x104 cells in 35 cm plate containing 2 ml of media and grown for 2 days to reach 50% confluency on the day of iron chelator /caged-iron chelator treatments. Organotypic 3 dimensional (3D) raft culture using de-epidermalised dermis (DED):

- Glycerol preserved skin (Euro Skin Bank, Netherlands) was washed and incubated in phosphate buffered saline (PBS) at 37°C for up to 10 days. Epidermis was then

mechanically removed using Forceps and the de-epidermalized dermis was cut into 2 x 2 cm squares and placed in culture plates with the papillary dermal surface on the underside. Stainless steel rings were placed on top of the dermis, and 5x 10s FEK4 fibroblasts were inoculated into the rings on the reticular dermal surface. Following an overnight incubation, the de-epidermalized dermis (DED) was inverted to orient the papillary dermal surface on top before the rings were replaced. Then 3 x 105 HaCaT keratinocytes were seeded inside the rings onto the dermis. After 2 days, the dermis was raised to the air-liquid interface in the same orientation, by placing the composites on stainless steel grids. The cultures were then incubated for an additional 17 days. On the 17th day, HaCaT Raft-DEDs were removed from the grids, fixed in 10% formalin and embedded in paraffin. De-parafinized sections were stained with haematoxylin and eosin for histological examination.

The medium used for this experiment was the rich RM+ [i.e. DME and Ham's F12 medium in a ratio of 3: 1 (v/v) supplemented with 10% FBS, hydrocortisone (0.4 yg/ml), cholera toxin (10~10 M), epidermal growth factor (10 ng/ml), insulin(5 pg/ml), transferrin (5 Mg/mi), liothyronine (2 x 10"11 M), 0.25% sodium bicarbonate, 2 mM L-glutamine and 50 lU/ml of each of penicillin/ streptomycin (P/S)] that allows the skin cell to achieve a higher proliferative state, and was refreshed every 3 days. 2.1.2 - Treatments

Stock solutions: - Desferoxamine mesylate (DFO) ( W 657): The DFO stock solution was prepared at the final concentration of 100 mM in H20. Aliquots were kept at -20°C until required.

- Pyridoxal isonicotinoyl hydrazone (PIH) (MW 286): PIH powder was first dissolved in 1 N HCI at the final concentration of 500 mM and then further diluted in PBS to obtain a 25 mM stock solution. Because of the tendency of the stock solution to precipitate over time, for experiments involving PIH treatment, the stock solution was prepared freshly on the day of treatments.

- SIH (MW 241): The SIH stock solution was prepared at the final concentration of 100 mM in DMSO. - CIC stock solutions: Novel chelators (1) i.e. hydroxycinnamoyl-SIH (MW 387.39), (3) i.e. hydroxycinnamoyl-PIH (MW 432.43), (5) i.e. aminocinnamoyl-SIH (MW 460.48) and (10) i.e. aminocinnamoyl- PIH (MW 505.52) and compounds 2NPE-PIH (MW 435) and 2NPE-SIH -(MW 390) were prepared at the final concentrations of 50-200 mM in DMSO, depending on the experimental requirement (Yiakouvaki A, Savovic' J, AI-QenaeiA, Dowden J, Pourzand C. J Invest Dermatol. 2006, 126:2287-2295).

To avoid the toxicity of DMSO in cell treatments with stock solutions made in DMSO for cell treatments, the DMSO's final concentration in conditioned media (CM) was kept to equal or less than 01% V/V.

Monolayer cell cultures: Compounds were added to cell culture media from stock solutions at the required final concentrations. The treatments were done from 24-72 h, depending on the experimental requirement as detailed below.

3. Methods and Results

3.1 - UVA Uncaging

To generate the 'uncaged' profile of the compounds, the compounds were first prepared in DMSO at a final concentration of 1 mg/ml and then irradiated in quartz cuvettes with increasing UVA doses of 5, 10, 20, 50, 100, 250 and 500 kJ/m2 (i.e. UVA doses equivalent to 3 to 140 min midday sunlight exposure at sea level). The level of uncaging of the compounds was then evaluated by reverse phase HPLC 1 h after UVA irradiation by comparing the profile of UVA-irradiated samples to controls i.e. free chelators and coumarin or iminocoumarin photoproducts.

The UVA doses were measured using an IL1700 radiometer (International Light, Newbury, MA). All irradiations were performed with a broad-spectrum Sellas 4kW UVA lamp (Sellas, Germany). This lamp emits primarily UVA radiation (significant emission in the range of 350-400 nm). The incident dose rate was 160 W/m2. Irradiation was carried out in an air- conditioned room at 8°C in order to maintain the temperature of the cells/samples to approximately 25°C throughout the irradiation procedure. HPLC: Dionex UlttMate 3000 HPLC system was equipped with a Phenomenex Gemini 5 pm C-18 (150 x 4.6 mm) column with a flow rate of 1 ml/min. Mobile phase A was H20 containing 0.1% formic acid, B was MeCN (acetonitrile) containing 0.1% formic acid, using a HPLC gradient of 5% A to 60% A over a period of 10 min.

Figure 3 shows the ability of the present compounds (10) and (1) to undergo UVA induced cleavage to produce an iron chelator (PIH or SIH respectively).

For cell culture treatments, caged compound stock solutions were prepared in DMSO at final concentrations of 100 mM or 200 mM, depending on the experimental requirement and then irradiated at in quartz cuvettes at a UVA dose 250 kJ/m2. The cells were then treated with the UVA-irradiated (uncaged) compounds for 24-72 h. Prior to irradiation, the culture medium was removed from the plates, and the monolayer cells were washed thoroughly with PBS. Cells were then covered with PBS (i.e. 2 ml for 3 cm plate). This was followed b irradiation of cells at doses of 00, 250 or 500 kJ/m2 equivalent to 30, 70 or 140 min midday sunlight exposure at sea level. The PBS was then removed, and cells were incubated in their original cultured media (i.e. conditioned media, CM) with or without the compound for the appropriate incubation time (e. g. 1 h to 72 h) at 37°C. Control samples were treated the same except that they were not irradiated.

3.2 - ROS Production (DCFDA Assay) and Photoprotective Effects

In order to assess the reactive oxygen species (ROS) production, FEk4 cells grown for 2 days were treated with iron chelators and compounds of the present invention (5) for 18h prior to UVA irradiation. After UVA irradiation cells were washed twice with PBS and incubated with 5 μΜ CM-H2DCFDA for 20 min at 37°C. After additional washing with PBS, cells were detached by trypsinisation and analysed by flow cytometry on a Beckton

Dickinson Canto II machine. Data analysis was performed using FACSDiva software (Becton-Dickinson, Erembodegem, Belgium). Table 1 - Flow cytometric evaluation of intracellular ROS generation with DCFDA assay in skin cells treated with SIH (IC, 30 uM) or its aminocinnamoyl -based caged version i.e. compound 5, 30 uM - (CIC)) for 18h prior to UVA irradiation (n=5).

In the absence of an iron chelator (UVA sample), the increase in ROS is greatest. The compounds of the present invention show a reduced increase in ROS when exposed to UVA compared to an iron chelator (CIC+UVA vs IC+UVA). This shows the ability of the present compounds to reduce the production of ROS upon UVA exposure.

In order evaluate the photoprotective potential of the present compounds, FEK4 cells grown for 2 days were treated with SIH or its amminocinnamoyl-based caged version (5) for 24h prior to UVA irradiation. Flow cytometric ROS assays were performed 1 h after UVA irradiation and Annexin V/ propidium iodide assays were performed both at 4 and 24 h after UVA irradiation.

Annexin V/propidium iodide dual staining assay - Principle of the assay: Quantification of apoptotic, necrotic, and live cells was evaluated by flow cytometry.

Apoptotic cells were shown to express phosphatidyl serine (PS) on the outer layer of the plasma membrane. In the early stages of apoptosis, PS translocates from the inner part of the plasma membrane to the outer layer. Annexin-V-FLUOS is a phospholipid-binding protein with a high affinity for PS. Therefore it is suitable for the detection of apoptotic cells. On the other hand, necrotic cells that lose cell membrane integrity are stained with both Annexin-VFLUOS and PI. Therefore, Annexin-V-FLUOS and PI double-staining can differentiate between necrotic and apoptotic cells. Procedure:

After relevant treatments and incubation periods (i.e. 4h to 72h), cells were collected and washed with incubation buffer (10 mM Hepes/NaOH, pH 7.4, 5 M NaCI, 100 mM CaCI2). Then 5 x 105 cells were re-suspended in 100 μΙ of incubation buffer containing Annexin-V- FLUOS (20 μΙ/ml) and PI (20 pg/ml). Samples were then transferred to a 5 ml polystyrene round-bottom tube and incubated for 20 min at RT under dark condition. Finally 400 μΙ of incubation buffer was added.

Table 2 - Flow cytometric evaluation of percentage of live cells 4 or 24h following UVA irradiation (500kJ/m2) of skin cells pre-treated with above IC or compound (5) for 18h (30 uM) (n=8).

Table 2 shows that the present compounds are able to increase the % of live cells when exposed to UVA as compared to standard iron chelators.

3.3 - Cell Impact and Toxicity 3.3.1 - Annexin V/propidium iodide and BrdU assays

For evaluation of the inherent toxicity/antiproliferative activity of the iron chelators, HaCaT cells grown for 2 days were treated with desferrioxamine (DFO) or PIH for 72 h at a final concentration of 100 μΜ prior to Annexin V/propidium iodide and BrdU assays.

BrdU assay - Principle of the assay; During cell proliferation the DNA has to be replicated before the cell is divided into two daughter cells. This close association between DNA synthesis and cell doubling makes the measurement of DNA synthesis very attractive for assessing celf proliferation. If labelled DNA precursors are added to the cell culture, cells that are about to divide incorporate the labelled nucleotide into their DNA. The thymidine analogue 5-bromo-2'-deoxy-uridine (BrdU) is a synthetic nucleotide that can be incorporated into the newly synthesized DNA of replicating cells (during the S phase of the cell cycle), by substituting for thymidine during DNA replication. Antibodies specific for BrdU can then be used to detect the incorporated chemical, thus indicating cells that were actively replicating their DNA. Binding of the antibody requires the denaturation of the DNA by exposing the cells to acid. FITC- conjugated secondary antibodies will then allow the detection of the "newly synthesized" DNA that will fluoresce green. The denatured DNA can be stained with propidium iodide (PI) and will fluoresce red.

BrdU Pulsing: To pujse cells, 10 μΜ BrdU was added to cells for 1 h at 37°C. For the negative control no BrdU was added. After incubation, cells were washed with PBS, then harvested with 0.25% (w/v %) trypsin, and collected in the CM and kept on ice. Cells were then centrifuged at 1000 rpm (120 x g) for 8 min in a Falcon 6/300 MSE centrifuge pre-cooled to 4°C. Medium was then removed. To permeabilise the cells, 5ml of. ice-cold 70% ethanol was added slowly, drop-wise onto them while vortexing to avoid formation of clumps. The cells were left on ice for a minimum of 30 min and then stored at 4°C prior to BrdU staining.

BrdU Staining:

Cells were first centrifuged at 2000 rpm (120 x g) to remove ethanol and then washed twice with PBS. Then the DNA was denatured by resuspending the cell suspension in 2M hydrochloric acid (HCI), for 30min with occasional mixing. This step allows the access of the anti-BrdU antibody to its epitope in the DNA. Cells were then centrifuged at 1000 rpm (120 x g) to remove the HCI, followed by washing with PBS-T (PBS + 0.1 % BSA + 0.2% Tween20, pH7.4). Cells were then stained with the anti-BrdU primary antibody for 20tnin at room temperature (RT) in the dark. Following a second wash with PBS-T, the cell suspension was incubated with the FITC-conjugated secondary antibody for 20 min (at RT in the dark). Cells were then washed with PBS-T and then RNAs were eliminated, by treating the cells with RNAse (DNAse-free) for 15min at RT. Next PI was added and cells were further incubated in the dark for 30min. RNAse treatment is necessary because PI incorporates into both DNA and RNA, but we are only interested in the signal coming from PI incorporated into DNA. Cells were then analyzed by flow cytometry. Fluorochromes were excited by a 488nm laser. The FITC fluorescence was collected between 515 and 545nm and the PI fluorescence was collected above 580nm. Pulse processing of the PI signal was used to distinguish true G2 from G1 doublets and to eliminate the latter (i.e to gate G2 in our experiment). 20,000 events were collected, at a low flow rate setup. The results are shown in Figures 4 and 5. Unlike clinical iron chelator desferoxamine (DFO), PIH does not exhibit any toxicity up to 72 hours post treatment (Figure 4). Further, unlike clinical iron chelator desferoxamine (DFO), PIH does not exhibit any antiproliferative activity (i.e. g1/S arrest) up to 72 hours post treatment (Figure 5). 3.3.2 - 3D raft DED cultures

After 7 days of raising the HaCaT Raft-DEDs, the 3D cultures were treated with DFO or PIH or the compounds of the present invention (10) (+/- UVA) at a final concentration of 100 μΜ for 72 h. The cultures were then incubated for an additional 10 days (in the absence of compounds). On the 10th day, HaCaT Raft-DEDs were removed from the grids, fixed in 10% formalin and embedded in paraffin. De-parafinized sections were stained with haematoxylin and eosin for histological examination. The results are shown in Figures 6 and 7. Treatment with PIH resulted in epithelial stratification with well-preserved morphologic differentiation. The stratum corneum was also distinct, which was comparable to the control (Figure 6). Similar results are observed for the compounds of the present invention (Figure 7) therefore confirming a lack of inherent toxicity. These results contrast with treatment with DFO (Figure 6).

All publications and patents and patent applications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in chemistry, biology or related fields are intended to be within the scope of the following claims.