Title:
Imidazo[1, 2-a] pyrazines for the treatment of irritable bowel syndrome
Kind Code:
A1


Abstract:
Provided herein are methods for treating a subject afflicted with irritable bowel syndrome comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition that comprises a pharmaceutically acceptable carrier and a compound of the formula 1embedded image

wherein:

X is CHR5, NR5, O, S, S(O)n or a single bond, wherein n is equal to 0, 1 or 2;

D is aryl or heteroaryl attached through an unsaturated carbon atom and wherein said aryl or heteroaryl is optionally substituted at any available position with from 1-5 of A1, A2, A3, A4 and A5; and

R2 is C1-4 alkyl or C3-8 cycloalkyl, each of which is optionally substituted with from 1-3 hydroxy, halogen or C1-4 alkoxy, or wherein when X is a bond, R2 is CN, CF3, or C2F5.




Inventors:
Bakthavatchalam, Rajagopal (US)
Wilde, Richard G. (US)
Gilligan, Paul J. (US)
Application Number:
10/427234
Publication Date:
11/27/2003
Filing Date:
05/01/2003
Assignee:
BAKTHAVATCHALAM RAJAGOPAL
WILDE RICHARD G.
GILLIGAN PAUL J.
Primary Class:
International Classes:
A61K31/4985; A61P3/04; A61P25/22; A61P25/24; A61P43/00; C07D487/04; (IPC1-7): A61K31/498
View Patent Images:



Primary Examiner:
BERCH, MARK L
Attorney, Agent or Firm:
HENRY HADAD (PRINCETON, NJ, US)
Claims:

What is claimed is:



1. A method of treating a subject afflicted with irritable bowel syndrome comprising administering to said subject a therapeutically effective amount of a pharmaceutical composition comprising a pharmaceutically acceptable carrier and a compound of the formula I: 10embedded image wherein: X is CHR5, NR5, O, S, S(O)n or a single bond, wherein n is equal to 0, 1 or 2; D is aryl or heteroaryl attached through an unsaturated carbon atom and wherein said aryl or heteroaryl is optionally substituted at any available position with from 1-5 of A1, A2, A3, A4 and A5; A1, A2, A3, A4 and A5 are each independently H, C1-6 alkyl, C3-6 cycloalkyl, halo, C1-4 haloalkyl, cyano, nitro, —OR12, SH, —S(O)nR13, —COR12, —CO2R12, —OC(O)R13, —NR11COR12, —N(COR12)2, —NR11CONR12R14, or wherein A1, A2, A3, A4 and A5 are each independently phenyl or phenyl substituted with from 1 to 4 of C1-3 alkyl, C1-3 alkoxy, halo, cyano, dimethylamino, CF3, C2F5, OCF3, SO2Me or acetyl; R1 is C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl, C3-8 cycloalkyl, C4-12 cycloalkylalkyl, NR6R7 or —C(R8) (R9)—O—R10; R2 is C1-4 alkyl or C3-8 cycloalkyl, each of which is optionally substituted with from 1-3 hydroxy, halogen or C1-4 alkoxy, or wherein when X is a bond, R2 is CN, CF3, or C2F5; R3 and R4 are independently H, C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-5 cycloalkyl, C1-4 alkoxy, C1-4 haloalkyl, C1-4 haloalkoxy, halogen, CN, or NR6R7; R5 is H, C1-4 alkyl or C3-8 cycloalkyl; R6 and R7 are each independently H, C1-4 alkyl, C1-4 haloalkyl, C2-8 alkoxyalkyl, C3-6 cycloalkyl, C4-12 cycloalkylalkyl, aryl, aryl(C1-4 alkyl)-, heteroaryl or heteroaryl(C1-4 alkyl)-; R8 and R9 are each independently H or C1-4 alkyl, or R8 and R9 are taken together as ═CH2; R10 is H or C1-4 alkyl; R11 is H, C1-4 alkyl, C3-7 cycloalkyl, C4-12 cycloalkylalkyl, phenyl or benzyl, each phenyl or benzyl optionally substituted on the aryl moiety with 1-3 groups of C1-4 alkyl, halogen, C1-4 haloalkyl, nitro, C1-4 alkoxy, C1-4 haloalkoxy, or dimethylamino; and, R12, R13 and R14 are each independently H, C1-6 alkyl, C3-10 cycloalkyl, C4-16 cycloalkylalkyl or C1-4 haloalkyl.

2. The method of claim 1, wherein X is a single bond.

3. The method of claim 1, wherein D is phenyl.

4. The method of claim 3, wherein the phenyl is 11embedded image and wherein each of A1, A2 and A3 is independently H, C1-6 alkyl, C1-6 alkoxy, halogen, C1-4 haloalkyl or OR12.

5. The method of claim 4, wherein A1 is H, CH3 or Cl.

6. The method of claim 4, wherein A2 is Cl, —OCH3 or —OCHF2.

7. The method of claim 4, wherein A3 is H or CH3.

8. The method of claim 4, wherein: A1 is H, CH3 or Cl; A2 is Cl, —OCH3 or —OCHF2 and A3 is H or CH3.

9. The method of claim 1, wherein R1 is —C(R8)(R9)—O—R10.

10. The method of claim 9, wherein each of R8, R9 and R10 are independently H or C1-4 alkyl.

11. The method of claim 10, wherein R8 is H.

12. The method of claim 10, wherein R9 is C2H5 or C3H7.

13. The method of claim 12, wherein R10 is H.

14. The method of claim 10, wherein R8 is H, R9 is C2H5 or C3H7 and R10 is H.

15. The method of claim 1, wherein R2 is unsubstituted C1-4 alkyl.

16. The method of claim 15, wherein R1 is C2H5.

17. The method of claim 1, wherein each of R3 and R4 are H 18. The method of claim 1, wherein R1 is —C(R8)(R9)—O—R10, R is unsubstituted C1-4 alkyl, each of R3 and R4 is H, X is a single bond and D is phenyl of the formula 12embedded image wherein R8 is H, R9 is C2H5 or C3H7, R10 is H, each of Al, is H, A2 is Cl, —OCH3 or —OCHF2 and A3 is H.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of co-pending U.S. application Ser. No. 09/905,097, filed Jul. 13, 2001, now allowed, which in turn claims priority of provisional application Serial No. 60/218,339. These priority applications are hereby incorporated herein in their entireties.

FIELD OF THE INVENTION

[0002] This invention relates to compounds which are novel imidazo[1,2-a]pyrazines, and to the use of such compounds as CRF receptor antagonists in the treatment of various neurological disorders.

BACKGROUND OF THE INVENTION

[0003] Corticotropin releasing factor (herein referred to as CRF), a 41 amino acid peptide, is the primary physiological regulator of proopiomelanocortin (POMC)-derived peptide secretion from the anterior pituitary gland [J. Rivier et al., Proc. Nat. Acad. Sci. (USA) 80:4851 (1983); W. Vale et al., Science 213:1394 (1981)]. In addition to its endocrine role at the pituitary gland, immunohistochemical localization of CRF has demonstrated that the hormone has a broad extrahypothalamic distribution in the central nervous system and produces a wide spectrum of autonomic, electrophysiological and behavioral effects consistent with a neurotransmitter or neuromodulator role in brain [W. Vale et al., Rec. Prog. Horm. Res. 39:245 (1983); G. F. Koob, Persp. Behav. Med. 2:39 (1985); E. B. De Souza et al., J. Neurosci. 5:3189 (1985)]. There is also evidence that CRF plays a significant role in integrating the response of the immune system to physiological, psychological, and immunological stressors [J. E. Blalock, Physiological Reviews 69:1 (1989); J. E. Morley, Life Sci. 41:527 (1987)].

[0004] Clinical data provide evidence that CRF has a role in psychiatric disorders and neurological diseases including depression, anxiety-related disorders and feeding disorders. A role for CRF has also been postulated in the etiology and pathophysiology of Alzheimer's disease, Parkinson's disease, Huntington's disease, progressive supranuclear palsy and amyotrophic lateral sclerosis as they relate to the dysfunction of CRF neurons in the central nervous system [for review see E. B. De Souza, Hosp. Practice 23:59 (1988)].

[0005] In affective disorder, or major depression, the concentration of CRF is significantly increased in the cerebral spinal fluid (CSF) of drug-free individuals [C. B. Nemeroff et al., Science 226:1342 (1984); C. M. Banki et al., Am. J. Psychiatry 144:873 (1987); R. D. France et al., Biol. Psychiatry 28:86 (1988); M. Arato et al., Biol Psychiatry 25:355 (1989)]. Furthermore, the density of CRF receptors is significantly decreased in the frontal cortex of suicide victims, consistent with a hypersecretion of CRF [C. B. Nemeroff et al., Arch. Gen. Psychiatry 45:577 (1988)]. In addition, there is a blunted adrenocorticotropin (ACTH) response to CRF (i.v. administered) observed in depressed patients [P. W. Gold et al., Am J. Psychiatry 141:619 (1984); F. Holsboer et al., Psychoneuroendocrinology 9:147 (1984); P. W. Gold et al., New Eng. J. Med. 314:1129 (1986)].

[0006] Preclinical studies in rats and non-human primates provide additional support for the hypothesis that hypersecretion of CRF may be involved in the symptoms seen in human depression [R. M. Sapolsky, Arch. Gen. Psychiatry 46:1047 (1989)]. There is preliminary evidence that tricyclic antidepressants can alter CRF levels and thus modulate the numbers of CRF receptors in brain [Grigoriadis et al., Neuropsychopharmacology 2:53 (1989)].

[0007] It has also been postulated that CRF has a role in the etiology of anxiety-related disorders. CRF produces anxiogenic effects in animals and interactions between benzodiazepine/non-benzodiazepine anxiolytics and CRF have been demonstrated in a variety of behavioral anxiety models [D. R. Britton et al., Life Sci. 31:363 (1982); C. W. Berridge and A. J. Dunn Regul. Peptides 16:83 (1986)]. Preliminary studies using the putative CRF receptor antagonist a-helical ovine CRF (9-41) in a variety of behavioral paradigms demonstrate that the antagonist produces “anxiolytic-like” effects that are qualitatively similar to the benzodiazepines [C. W. Berridge and A. J. Dunn Horm. Behav. 21:393 (1987), Brain Research Reviews 15:71 (1990)].

[0008] Neurochemical, endocrine and receptor binding studies have all demonstrated interactions between CRF and benzodiazepine anxiolytics, providing further evidence for the involvement of CRF in these disorders. Chlordiazepoxide attenuates the “anxiogenic” effects of CRF in both the conflict test [K. T. Britton et al., Psychopharmacology 86:170 (1985); K. T. Britton et al., Psychopharmacology 94:306 (1988)] and in the acoustic startle test [N. R. Swerdlow et al., Psychopharmacology 88:147 (1986)] in rats. The benzodiazepine receptor antagonist (Ro15-1788), which was without behavioral activity alone-in the operant conflict test, reversed the effects of CRF in a dose-dependent manner while the benzodiazepine inverse agonist (FG7142) enhanced the actions of CRF [K. T. Britton et al., Psychopharmacology 94:306 (1988)].

[0009] It has been further postulated that CRF has a role in immunological, cardiovascular or heart-related diseases such as hypertension, tachycardia and congestive heart failure, stroke, osteoporosis, premature birth, psychosocial dwarfism, stress-induced fever, ulcer, diarrhea, post-operative ileus and colonic hypersensitivity associated with psychopathological disturbance and stress.

[0010] The mechanisms and sites of action through which the standard anxiolytics and antidepressants produce their therapeutic effects remain to be elucidated. It has been hypothesized however, that they are involved in the suppression of the CRF hypersecretion that is observed in these disorders. Of particular interest is that preliminary studies examining the effects of a CRF receptor antagonist (a-helical CRF9-41) in a variety of behavioral paradigms have demonstrated that the CRF antagonist produces “anxiolytic-like” effects qualitatively similar to the benzodiazepines [for review see G. F. Koob and K. T. Britton, In: Corticotropin-Releasing Factor: Basic and Clinical Studies of a Neuropeptide, E. B. De Souza and C. B. Nemeroff eds., CRC Press p221 (1990)].

[0011] The following publications each describe CRF antagonist compounds; however, none disclose the compounds provided herein: WO95/10506; WO99/51608; WO97/35539; WO99/01439; WO97/44308; WO97/35846; WO98/03510; WO99/11643; PCT/US99/18707; WO99/01454; and, WO00/01675.

SUMMARY OF THE INVENTION

[0012] This invention provides a compound of the formula (I): 2embedded image

[0013] wherein: X is CHR5, NR5, O, S, S(O)n or a single bond, wherein n is equal to 0, 1 or 2; D is aryl or heteroaryl attached through an unsaturated carbon atom and wherein said aryl or heteroaryl is optionally substituted with from 1-5 A1-A5; R1 is C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl, C3-8 cycloalkyl, C4-12 cycloalkylalkyl, NR6R7 or —C(R8)(R9)—O-R10; R2 is C1-4 alkyl or C3-8 cycloalkyl, each of which is optionally substituted with from 1-3 hydroxy, halogen or C1-4 alkoxy, or wherein when X is a bond, R2 is optionally also CN, CF3, C2F5, C1-4 alkyl or C3-8 cycloalkyl, each of which C1-4 alkyl or C3-8 cycloalkyl is optionally substituted with from 1-3 hydroxy, halogen and C1-4 alkoxy; R3 and R4 are selected independently from H, C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-5 cycloalkyl, C1-4 alkoxy, C1-4 haloalkyl, C1-4 haloalkoxy, halogen, CN, or NR6R7; R5 is H, C1-4 alkyl or C3-8 cycloalkyl; R6 and R7 are each independently H, C1-4 alkyl, C1-4 haloalkyl, C2-8 alkoxyalkyl, C3-6 cycloalkyl, C4-12 cycloalkylalkyl, aryl, aryl(C1-4 alkyl)-, heteroaryl or heteroaryl(C1-4 alkyl)-; R8 and R9 are each independently H or C1-4 alkyl, or R8 and R9 are taken together as ═CH2, C2-4 alkenyl, C2-4 alkynyl; and, R10 is H or C1-4 alkyl. Preferred embodiments of this invention are set forth hereinbelow.

[0014] Said compounds antagonize CRF receptors, that is, they bind to the receptors such that CRF is inhibited from binding to the antagonized receptors. The compounds of this invention are thus useful as therapeutic agents in conditions characterized by excessive CRF expression, and this invention thus provides methods of treating a subject afflicted with a disorder, e.g., an anxiety- or depression-related disorder, characterized by CRF overexpression.

DETAILED DESCRIPTION OF THE INVENTION

[0015] This invention provides a compound of the formula (I): 3embedded image

[0016] wherein the various substituents are as described hereinbelow.

[0017] R1 is C1-10 alkyl, C2-10 alkenyl, C2-10 alkynyl, C3-8 cycloalkyl, C4-12 cycloalkylalkyl, NR6R7 or —C(R8) (R9)—O—R10. R2 is C14 alkyl or C3-8 cycloalkyl, each of which is optionally substituted with from 1-3 hydroxy, halogen or C1-4 alkoxy, or wherein when X is a bond, R2 is optionally also CN, CF3, C2F5, C1-4 alkyl or C3-8 cycloalkyl, each of which C1-4 alkyl or C3-8 cycloalkyl is optionally substituted with from 1-3 hydroxy, halogen and C1-4 alkoxy. R3 and R4 are each selected independently from H, C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl, C3-5 cycloalkyl, C1-4 alkoxy, C1-4 haloalkyl, C1-4 haloalkoxy, halogen, CN, or NR6R7. R5 is H, C1-4 alkyl or C3-8 cycloalkyl. R6 and R7 are each independently H, C1-4 alkyl, C1-4 haloalkyl, C2-8 alkoxyalkyl, C3-6 cycloalkyl, C4-12 cycloalkylalkyl, aryl, aryl(C1-4 alkyl)-, heteroaryl or heteroaryl(C1-4 alkyl)-. R8 and R9 are each independently H or C14 alkyl, or R8 and R9 are taken together as ═CH2, C2-4 alkenyl, C2-4 alkynyl. R10 is H or C14 alkyl. R11 is H, C1-4 alkyl, C3-7 cycloalkyl, C4-12 cycloalkylalkyl, phenyl or benzyl, each phenyl or benzyl optionally substituted on the aryl moiety with 1-3 groups of C1-4 alkyl, halogen, C1-4 haloalkyl, nitro, C1-4 alkoxy, C14 haloalkoxy, or dimethylamino. R12, R13 and R14 are each independently H, C1-6 alkyl, C3-10 cycloalkyl, C4-16 cycloalkylalkyl or C1-4 haloalkyl.

[0018] X is CHR5, NR5, O, S, S(O)n or a single bond, wherein n is equal to 0, 1 or 2. D is aryl or heteroaryl attached through an unsaturated carbon atom, wherein said aryl is optionally substituted at any available position with from 1-5 of, and said heteroaryl is optionally substituted with from 1-4 of, A1, A2, A3, A4 and A5 A1, A2, A3, A4 and A5 are each independently H, C1-6 alkyl, C3-6 cycloalkyl, halo, C1-4 haloalkyl, cyano, nitro, —OR12, SH, —S(O)nR13, —COR12, —CO2R —OC(O)R13, —NR11COR12, —N(COR12)2, —N11CONR12R14, or wherein A1, A2, A3, A4 and A5 are each independently phenyl or phenyl substituted with from 1 to 4 of C1-3 alkyl, C13 alkoxy, halo, cyano, dimethylamino, CF3, C2F5, OCF3, SO2Me or acetyl.

[0019] “Aryl” denotes either the 6-carbon benzene ring or the condensed 6-carbon rings of other aromatic derivatives (see, e.g., Hawley's Condensed Chemical Dictionary (13 ed.), R. J. Lewis, ed., J. Wiley & Sons, Inc., New York (1997)); aryl includes, without limitation, phenyl, napthyl, indanyl and indenyl. “Heteroaryl” rings are aryl rings in which one or more, typically from 1-4, of the ring-member carbon atoms is replace by an atom other than a carbon atom, i.e., a heteroatom (typically O, N or S). Heteroaryl includes, without limitation: pyridyl, pyrimidinyl, pyrazinyl, triazolyl, tetrazolyl, indazolyl, thienyl, isoxazolyl, 2,3-dihydrobenzofuranyl, 2,3-dihydrobenzsothienyl, 2,3-dihydrobenzothienyl-S-oxide, indolinyl, benzoxazolin-2-on-yl and benzodioxolanyl. “Alkyl” means saturated hydrocarbon chains, branched or unbranched, having the specified number of carbon atoms. “Alkenyl” means hydrocarbon chains of either a straight or branched configuration and one or more unsaturated carbon-carbon bonds, which may occur in any stable point along the chain, such as ethenyl, propenyl, and the like. “Alkynyl” means hydrocarbon chains of either a straight or branched configuration and one or more triple carbon-carbon bonds, which may occur in any stable point along the chain, such as ethynyl, propynyl and the like. “Alkoxy” means an alkyl group of indicated number of carbon atoms attached through an oxygen bridge. “Cycloalkyl” means saturated ring groups, including mono-,bi- or polycyclic ring systems, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and so forth. “Halo” or “halogen” means fluoro, chloro, bromo, and iodo. “Haloalkyl” means both branched and straight-chain alkyls having the specified number of carbon atoms, substituted with 1 or more halogens. “Haloalkoxy” means an alkoxy group substituted by at least one halogen atom. “Substituted” means that one or more hydrogen on the designated atom is replaced with a selection from the indicated group, provided that the designated atom's normal valency is not exceeded, and that the substitution results in a stable compound. “Unsubstituted” atoms bear all of the hydrogen atoms dictated by their valency. When a substituent is keto, then 2 hydrogens on the atom are replaced. Combinations of substituents and/or variables are permissible only if such combinations result in stable compounds; by “stable compound” or “stable structure” is meant a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.

[0020] Preferably, R1 is —C(R8)(R9)—O—R10. More preferably, presently, R8 is H, R9 is C2H5 or C3H7 and R10 is C2H5. Preferably, R2 is unsubstituted C1-4 alkyl; more preferably, presently, R2 is C2H5. R3 and R4 are preferably each H. X is preferably a single bond.

[0021] D is preferably phenyl, more preferably a phenyl group of the formula 4embedded image

[0022] wherein each of A1, A2 and A3 is selected from the group consisting of H, C1-6 alkyl, C1-6 alkoxy, halogen and C1-4 haloalkyl. Even more preferably: A1 is H, CH3 or Cl; A is Cl, —OCH3 or —OCHF2; and, A3 is H or CH3. Most preferably, presently, A1 is C1 and A3 is H.

[0023] Each of R1-R12, X, D and A1-A5 are any of the possible members of the groups listed hereinabove for these substituents. R2, for example, being C1-4 alkyl or C3-8 cycloalkyl is each and every one of the members of these groups, i.e., is C1, C2, C3 and C4 alkyl, as well as C3, C4, C5, C6, C7 and C8 cycloalkyl. Moreover, selection of a substituent as a specific member of one of its groups does not limit the choice of the other substituents to less than all of the available selections.

[0024] R1 is preferably —CR8R9R10, and each of R8, R9 and R10 is preferably H, C1, C2, C3 or C4 alkyl. Moreover, each of the substituents is any one of these five possibilities independently of the identity of the other substituents. Thus, there are at least 125 groups of preferred compounds, each of which is characterized by a different, but preferred, combination of R8, R9 and R10 in R1. These groups of compounds are listed in Tables A and B (hereinbelow). 1

TABLE A
R8 Alkyl
R9HC1C2C3C4
HA1 A2 A3 A4 A5 
C1 AlkylA6 A7 A8 A9 A10
C2 AlkylA11A12A13A14A15
C3 AlkylA16A17A18A19A20
C4 AlkylA21A22A23A24A25

[0025] 2

TABLE B
R10 Alkyl
R8 + R9HC1C2C3C4
X1 B1 B2 B3 B4 B5 
X2 B6 B7 B8 B9 B10
X3 B11B12B13B14B15
X4 B16B17B18B19B20
X5 B21B22B23B24B25
X6 B26B27B28B29B30
X7 B31B32B33B34B35
X8 B36B37B38B39B40
X9 B41B42B43B44B45
X10B46B47B48B49B50
X11B51B51B53B54B55
X12B56B57B58B59B60
X13E61B62B63B64B65
X14B66B67B68B69B70
X15B71B72B73B74B75
X16B76B77B78B79B80
X17B81B82B83B84B85
X18B86B8 B88B89B90
X19B91B92B93B94B95
X20B96B97B98B99 B100
X21 B101 B102 B103 B104 B105
X22 B106 B107 B108 B109 B110
X23 B111 B112 B113 B114 B115
X24 B116 B117 B118 B119 B120
X25 B121 B122 B123 B124 B125

[0026] Table A specifies the identity of the substituent “R8” in preferred compounds provided herein; these are listed, in the top row from left to right, as H, and then C1, C2, C3 and C4 alkyl. The identity of the substituent “R9” in preferred compounds is also given, along the left side, from top to bottom, as H, and then C1, C2, C3 and C4 alkyl. Thus, each cell of the table identifies a specific combination of R8 and R9 in a preferred compound. Thus, each cell of the table identifies a specific combination of R8 and R9 in a preferred compound. Each cell is itself identified by an alphanumeric combination specifying the cell's location within the table.

[0027] Table B specifies the identity of the substituent “R10” in preferred compounds provided hererein; these are listed, in the top row from left to right, as H, and then C1, C2, C3 and C4 alkyl. Moreover, the R8/R9 combinations set forth in in Table 1 are listed along the left side of the table, from top to bottom, in terms of their cell number from Table A (e.g., “X1” refers to that set of compounds wherein R8 and R9 are each H). Each cell of Table B thus specifies a specific combination of R8, R9 and R10 (e.g., “B1” refers to that set of compounds wherein each of R8, R9 and R10 are H)

[0028] R2 is preferably C1, C2, C3 or C4 alkyl (each being unsubstituted). Table C hereinbelow lists the combinations of each of these with each of the R8/R9/R10 combinations from Table B: 3

TABLE C
R1 ALKYL
R8/R9/R10C1C2C3C4
B1C1C2C3C4
B2C5C6C7C8
B3C9C10C11C12
B4C13C14C15C16
B5C17C18C19C20
B6C21C22C23C24
B7C25C26C27C28
B8C29C30C31C32
B9C33C34C35C36
B10C37C38C39C40
B11C41C42C43C44
B12C45C46C47C48
B13C49C50C51C52
B14C53C54C55C56
B15C57C58C59C60
B16C61C62C63C64
B17C65C66C67C68
B18C69C70C71C72
B19C73C74C75C76
B20C77C78C79C80
B21C81C82C83C84
B22C85C86C87C88
B23C89C90C91C92
B24C93C94C95C96
B25C97C98C99C100
B26C101C102C103C104
B27C105C106C107C108
B28C109C110C111C112
B29C113C114C115C116
B30C117C118C119C120
B31C121C122C123C124
B32C125C126C127C128
B33C129C130C131C132
B33C133C134C135C136
B34C137C138C139C140
B35C141C142C143C144
B36C145C146C147C148
B37C149C150C151C152
B38C153C154C155C156
B39C157C158C159C160
B40C161C162C163C164
B41C165C166C167C168
B42C169C170C171C172
B43C173C174C175C176
B44C177C178C179C180
B45C181C182C183C184
B46C185C186C187C188
B47C189C190C191C192
B48C193C194C195C196
B49C197C198C199C200
B50C201C202C203C204
B51C205C206C207C208
B52C209C210C211C212
B53C213C214C215C216
B54C217C218C2190C220
B55C221C222C223C224
B56C225C226C227C228
B57C229C230C231C232
B58C233C234C235C236
B59C237C238C239C240
B60C241C242C243C244
B61C245C246C2247C248
B62C249C250C251C252
B63C253C254C255C256
B64C257C258C259C260
B65C261C262C263C264
B66C265C266C267C268
B67C269C270C271C272
B68C273C274C275C276
B69C277C278C279C280
B70C281C282C283C284
B71C285C286C287C288
B72C289C290C291C292
B73C293C294C295C296
B74C297C298C299C300
B75C301C302C303C304
B76C305C306C307C308
B77C309C310C311C312
B78C313C314C315C316
B79C317C318C319C320
B80C321C322C323C324
B81C325C326C327C328
B82C329C330C331C332
B83C333C334C335C336
B84C337C338C339C340
B85C341C342C343C344
B86C345C346C347C348
B87C349C350C351C352
B88C353C354C355C356
B89C357C358C359C360
B90C361C362C363C364
B91C365C366C367C368
B92C369C370C371C372
B93C373C374C375C376
B94C377C378C379C380
B95C381C383C383C384
B96C385C386C387C388
B97C389C390C391C392
B98C393C394C395C396
B99C397C398C399C400
B100C401C402C403C404
B101C405C406C407C408
B102C409C410C411C412
B103C413C414C415C416
B104C417C418C419C420
B105C421C422C423C424
B106C425C426C427C428
B107C429C430C431C432
B108C433C434C435C436
B109C437C438C439C440
B110C441C442C443C444
B111C445C446C447C448
B112C449C450C451C452
B113C453454C455C456
B114C457C458C459C460
B115C461C462C463C464
B116C465C466C467C468
B117C469C470C471C472
B118C473C474C475C476
B119C477C478C479C480
B120C481C482C483C484
B121C485C486C487C488
B122C489C490C491C492
B123C493C494C495C496
B124C497C498C499C500
B125C501C502C503C504

[0029] Also as described hereinabove, D is most preferably a phenyl substituted with A1 (presently preferably H or CH3), A2 (preferably Cl, —OCH3 or —OCHF2) and A3 (H or CH3). Tables D and DD hereinbelow identify individual sets of compounds containing each of the possible specific combinations of these groupings. Table D lists combinations of A1 and A3 (e.g., cell “D1” represents that set of compounds wherein A1 and A3 are each H); Table DD lists combinations of A1/A3 with the various presently preferred members of A (e.g., cell “DD1” represents that set of compounds wherein A2 is Cl and the A1/A3 combination is represented by cell “D1” (i.e., A1 and A3 are each H)): 4

TABLE D
A3
A1HCH3
HD1D2
CH3D3D4

[0030] 5

TABLE DD
A2
A1/A3C1—OCH3—OCHF2
D1DD1DD2DD3
D2DD4DD5DD6
D3DD7DD8DD9
D4DD10DD11DD12

[0031] Furthermore, as described hereinabove, this invention provides presently preferred compounds comprising combinations of any of the preferred members of R1 and R2 (identified in Table C hereinabove with the designations “C1-C500”) with any of the specific A1/A2/A3 combinations listed in Table DD; these R1*R2/A1*A2*A3 combinations, and hence, individual preferred compounds are listed specifically in Table E hereinbelow. Across the top row of the table, from left to right, are listed individual sets of compounds comprising combinations of the various specific, individual A1, A2 and A3 substituents of the phenyl ring D, as identified by their corresponding cell number in Table DD. The leftmost column of the table lists individual sets of compounds comprising the various specific, individual R1 and R2 substituents, as identified by their corresponding cell number in table C. In this regard, cell number Cl (and hence, compounds in which R1 is Cl alkyl, R2 is —CR8R9OCR10, and R8, R9 and R10 are each H) corresponds to the individual compounds listed in Table E as E1, E501, E1001, E1501, E2001, E2501, E3001, E3501, E4001, E4501, E5001 and E5501; the other cells of Table C (C2-C500) have a similar correspondence to the individual compounds listed in Table E.

[0032] In addition to the compounds described and listed hereinabove, this invention provides their corresponding pharmaceutically acceptable salt, radiolabelled, various stereoisomeric and prodrug forms. “Pharmaceutically acceptable salts” of compounds of this invention are also provided herein. The phrase “pharmaceutically acceptable” is employed to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

[0033] “Pharmaceutically acceptable salts” refer to derivatives of the disclosed compounds wherein the parent compound is modified by making acid or base salts thereof. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines, or alkali or organic salts of acidic residues such as carboxylic acids.

[0034] Pharmaceutically acceptable salts include the conventional non-toxic salts or the quaternary ammonium salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. Such conventional nontoxic salts include those derived from inorganic acids such as hydrochloric, hydrobromic, sulfuric, sulfamic, phosphoric, nitric and the like; and the salts prepared from organic acids such as acetic, propionic, succinic, glycolic, stearic, lactic, malic, tartaric, citric, ascorbic, pamoic, maleic, hydroxymaleic, phenylacetic, glutamic, benzoic, salicylic, sulfanilic, 2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethane disulfonic, oxalic, isethionic, and the like.

[0035] Pharmaceutically acceptable salt forms of compounds provided herein are synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts are, for example, prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. Lists of suitable salts are found in Remington's Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, p. 1418, the disclosure of which is hereby incorporated by reference.

[0036] Radiolabelled compounds, i.e. wherein one or more of the atoms described are replaced by a radioactive isotope of that atom (e.g. C replaced by 14C or by 11C, and H replaced by 3H or 18F), are also provided for herein. Such compounds have a variety of potential uses, e.g. as standards and reagents in determining the ability of a potential pharmaceutical to bind to neurotransmitter proteins, or for imaging compounds of this invention bound to biological receptors in vivo or in vitro.

[0037] Each of the stereoisomeric forms of this invention's compounds is also provided for herein. That is, the compounds can have one or more asymmetric centers or planes, and all chiral (enantiomeric and diastereomeric) and racemic forms of the compounds are included in the present invention. Many geometric isomers of olefins, C=N double bonds, and the like can also be present in the compounds, and all such stable isomers are contemplated in the present invention. Compounds are isolated in either the racemic form, or in the optically pure form, for example, by chiral chromatography or chemical resolution of the racemic form.

[0038] Prodrug forms of this invention's compounds are also provided for herein. Such “prodrugs” are compounds comprising this invention's compounds and moieties covalently bound to the parent compounds such that the portions of the parent compound most likely to be involved with toxicities in subjects to which the prodrugs have been administered are blocked from inducing such effects. However, the prodrugs are also cleaved in the subjects in such a way as to release the parent compound without unduly lessening its therapeutic potential. Prodrugs include compounds wherein hydroxy, amine, or sulfhydryl groups are bonded to any group that, when administered to a mammalian subject, cleaves to form a free hydroxyl, amino, or sulfhydryl group, respectively. Examples of prodrugs include, but are not limited to, acetate, formate, and benzoate derivatives of alcohol, and amine functional groups in the compounds of Formulae (I-III).

[0039] The compounds provided herein are, for example and without limitation, made by the synthetic routes and schemes set forth hereinbelow.

[0040] Synthesis

[0041] Imidazo[1,2-a]pyrazines (1) of the present invention may be prepared from intermediate compounds of Formula (2) using the procedures outlined in Scheme 1. 5embedded image

[0042] Compounds of Formula (2) (where L=leaving groups such as halogen) may be treated with ammonia or aqueous ammonia in the presence or absence an inert solvent such as alkyl alcohols, at reaction temperatures ranging from −80° C. to 250° C. to give products of Formula (3) (where L is halogen). Inert solvents may include, but are not limited to, lower alkanenitriles (1 to 6 carbons, preferably acetonitrile), dialkyl ethers (preferably diethyl ether), cyclic ethers (preferably tetrahydrofuran or 1,4-dioxane), N,N-dialkylformamides (preferably dimethylformamide), N,N-dialkylacetamides (preferably dimethylacetamide), cyclic amides (preferably N-methyl-pyrrolidin-2-one), dialkylsulfoxides (preferably dimethylsulfoxide), aromatic hydrocarbons (preferably benzene or toluene), alkyl esters (preferably EtOAc) or haloalkanes of 1 to 10 carbons and 1 to 10 halogens (preferably dichloromethane).

[0043] The resulting intermediates (3) may then be reacted with alpha haloketone derivatives in a solvent such as aliphatic alcohols or an inert solvent at temperatures ranging from −20° C. to 150° C. to give compounds of Formula (4). Inert solvents may include, but are not limited to, polyethers (preferably 1,2-dimethoxyethane), dialkyl ethers (preferably diethyl ether), cyclic ethers (preferably tetrahydrofuran or 1,4-dioxane) or aromatic hydrocarbons (preferably benzene or toluene).

[0044] The compounds of Formula (4) may be coupled to an aromatic compound of Formula (5) to give a compound of formula (6), with elimination of the leaving group (L). For compound (4), L represents a halide, psuedohalide (such as mesylate, tosylate or triflate), or thiomethyl. For compound (5), L represents groups such as lithium, bromomagnesium, chlorozinc, (dihydroxy) boron, (dialkoxy) boron, trialkylstannyl and the like. The coupling reaction may be performed in the presence of an appropriate catalyst, such as tetrakis(triphenylphosphine)palladium, bis(triphenyl-phosphine)palladium dichloride, [1,3-bis(diphenylphosphino)propane]nickel dichloride, etc. Two particularly useful methods involve the coupling of chloroheterocycles with in-situ-prepared arylzinc reagents according to the method of Negishi et al. (J. Org. Chem. 1977, 42, 1821), and the coupling with arylboronic esters according to the method of Suzuki et al. (Chem. Letters 1989, 1405). Appropriate solvents for reactions of this type usually include tetrahydrofuran, diethyl ether, dimethoxyethane, dimethylformamide, or dimethylsulfoxide. Typical temperatures range from ambient up to the boiling point of the solvent.

[0045] The compound of formula (6) may be converted to a compound of formula (7) by treatment with phosphorous oxyhalide in dialkylformamide. Compounds of formula (8) may be obtained from a compound of formula (7) by treatment with alkyllithiums, alkylmagnesiumhalides, alkyllithiumcuprates or alkylzinc reagents in an inert solvent such as tetrahydrofuran, diakylether or aromatic hydrocarbons.

[0046] The compound of formula (8) can be converted to a compound of invention (1) by alkylating the alcohol with alkyl halides in the presence of a base in an inert solvent. Bases may include, but are not limited to, alkali metal hydrides (preferably sodium hydride).Inert solvents include, but are not limited to, dialkyl ethers (preferably diethyl ether), cyclic ethers (preferably tetrahydrofuran or 1,4-dioxane), N,N-dialkylformamides (preferably dimethylformamide), N,N-dialkylacetamides (preferably dimethylacetamide), cyclic amides (preferably N-methylpyrrolidin-2-one), dialkylsulfoxides (preferably dimethylsulfoxide) or aromatic hydrocarbons (preferably benzene or toluene). Preferred reaction temperatures range from −20° C. to 100° C.

[0047] Alternatively, imidazo[1,2-a]pyrazine (1) of the present invention may be obtained by following the steps outlined in Scheme 2. A compound of Formula (4) may be converted to a compound of Formula (9) by following similar conditions for the conversion of compounds of formula (6) to (7) outlined in Scheme 1. Compound of formula (10) may be obtained from compound (9) by following conditions for the conversion of formula (7) to (8) as shown in Scheme 1. Compound (10) may be alkylated to compound (11) by similar conditions outlined for Formula (8) to (1) outlined in scheme 1. Finally compound of formula (11) can be converted to compound of invention (1) using the condition for the conversion of Formula (4) to (6). 6embedded image

[0048] Alternatively, imidazo[1,2-a]pyrazines of the present invention may be obtained by following the steps outlined in Scheme 3. The compound of Formula (7) may be oxidized to compound of Formula (12) by following well known methods outlined in literature (see: Comprehensive Organic Transformations by R. C. Larock, 1989, pp 604-614). 7embedded image

[0049] The compound of Formula (12) may be subjected to Wittig or Tebbe's reaction conditions to afford compound of Formula (13) which may be reduced to compound of Formula (14).

[0050] The nitrogen containing side chain analogs of imidazo[1,2-a]pyrazine derivatives can be synthesized by following procedures outlined in Scheme 4. 8embedded image

[0051] The compound of the Formula (3) may converted to 3-aminoimidazo[1,2-a}pyrazine derivative of Formula (15) by a three component condensation reaction consisting of primary amine, aldehyde and isonitriles in the presence of an acid in an inert solvent. Acids may include, but are not limited to alkanoic acids of 2 to 10 carbons (preferably acetic acid), haloalkanoic acids (2-10 carbons, 1-10 halogens, such as trifluoroacetic acid), alkanesulfonic acids of 1 to 10 carbons (preferably methanesulfonic acid), hydrochloric acid. Also acids include Lewis acids but not limited to aluminum halides, borontrifluoride etherates, LiBF4, Magnesium halides, tin halides, titanium halides, titanium alkoxides, zinc halides and scandium triflates. Inert solvents may include, but are not limited to, polyethers (preferably 1,2-dimethoxyethane), dialkyl ethers (preferably diethyl ether), cyclic ethers (preferably tetrahydrofuran or 1,4-dioxane), haloalkanes or aromatic hydrocarbons (preferably benzene or toluene). The compound of Formula (15) may be converted to the compound of Formula (17) by following similar conditions outlined in Scheme 1.

[0052] Moreover, in addition to compounds made by these routes and schemes, this invention provides pharmaceutical compositions comprising pharmaceutically acceptable carriers and therapeutically effective amounts of the compounds. “Pharmaceutically acceptable carriers” are media generally accepted in the art for the delivery of biologically active agents to animals, in particular, mammals. Such media are formulated according to a number of factors well within the purview of those of ordinary skill in the art to determine and account for. These include, without limitation: the type and nature of the active agent being formulated; the subject to which the agent-containing composition is to be administered; the intended route of administration of the composition; and, the therapeutic indication being targeted.

[0053] Pharmaceutically acceptable carriers include both aqueous and non-aqueous liquid media, as well as a variety of solid and semi-solid dosage forms. Such carriers can include a number of different ingredients and additives in addition to the active agent, such additional ingredients being included in the formulation for a variety of reasons, e.g., stabilization of the active agent, well known to those of ordinary skill in the art. Descriptions of suitable pharmaceutically acceptable carriers, and factors involved in their selection, are found in a variety of readily available sources, e.g., Remington 's Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, the contents of which are incorporated herein by reference.

[0054] Compounds provided herein are antagonists of receptors for corticotropin releasing factor (“CRF”), a 41 amino acid peptide that is the primary physiological regulator of pro-opiomelanocortin (POMC)-derived peptide secretion from the anterior pituitary gland [J. Rivier et al., Proc. Nat. Acad. Sci. (USA) 80:4851 (1983); W. Vale et al., Science 213:1394 (1981)]. Immunohistochemical localization of CRF has also demonstrated that CRF has a broad extrahypothalamic distribution in the central nervous system and produces a wide spectrum of autonomic, electrophysiological and behavioral effects consistent with a neurotransmitter or neuromodulator role in brain [W. Vale et al., Rec. Prog. Horm. Res. 39:245 (1983); G. F. Koob, Persp. Behav. Med. 2:39 (1985); E. B. De Souza et al., J. Neurosci. 5:3189 (1985)]. There is also evidence that CRF plays a significant role in integrating the response of the immune system to physiological, psychological, and immunological stressors [J. E. Blalock, Physiological Reviews 69:1 (1989); J. E. Morley, Life Sci. 41:527 (1987)].

[0055] CRF concentrations have been found to be significantly increased in the cerebral spinal fluid (CSF) of drug-free individuals afflicted with affective disorder or depression [C. B. Nemeroff et al., Science 226:1342 (1984); C. M. Banki et al., Am. J. Psychiatry 144:873 (1987); R. D. France et al., Biol. Psychiatry 28:86 (1988); M. Arato et al., Biol Psychiatry 25:355 (1989)]. Furthermore, the density of CRF receptors is significantly decreased in the frontal cortex of suicide victims, consistent with a hypersecretion of CRF [C. B. Nemeroff et al., Arch. Gen. Psychiatry 45:577 (1988)]. Moreover, there is a blunted adrenocorticotropin (ACTH) response to CRF (i.v. administered) observed in depressed patients [P. W. Gold et al., Am J. Psychiatry 141:619 (1984); F. Holsboer et al., Psychoneuroendocrinology 9:147 (1984); P. W. Gold et al., New Eng. J. Med. 314:1129 (1986)].

[0056] CRF produces anxiogenic effects in animals. Moreover, interactions between benzodiazepine/non-benzodiazepine anxiolytics and CRF have been demonstrated in a variety of behavioral anxiety models [D. R. Britton et al., Life Sci. 31:363 (1982); C. W. Berridge and A. J. Dunn Regul. Peptides 16:83 (1986)]. Preliminary studies using the putative CRF receptor antagonist alpha-helical ovine CRF (9-41) in a variety of behavioral paradigms demonstrate that the antagonist produces “anxiolytic-like” effects that are qualitatively similar to the benzodiazepines [C. W. Berridge and A. J. Dunn Horm. Behav. 21:393 (1987), Brain Research Reviews 15:71 (1990)]. Neurochemical, endocrine and receptor binding studies have all demonstrated interactions between CRF and benzodiazepine anxiolytics, providing further evidence for the involvement of CRF in these disorders. Chlordiazepoxide attenuates the “anxiogenic” effects of CRF in both the conflict test [K. T. Britton et al., Psychopharmacology 86:170 (1985); K. T. Britton et al., Psychopharmacology 94:306 (1988)] and in the acoustic startle test [N. R. Swerdlow et al., Psychopharmacology 88:147 (1986)] in rats. The benzodiazepine receptor antagonist (Ro15-1788), which was without behavioral activity alone in the operant conflict test, reversed the effects of CRF in a dose-dependent manner while the benzodiazepine inverse agonist (FG7142) enhanced the actions of CRF [K. T. Britton et al., Psychopharmacology 94:306 (1988)]. The contents of the above-cited documents are incorporated herein by reference.

[0057] Thus, compounds provided herein which, because of their antagonism of CRF receptors, alleviate the effects of CRF overexpression are expected to be useful in treating these and other disorders. Such treatable disorders include, for example and without limitation: affective disorder, anxiety, depression, headache, irritable bowel syndrome, post-traumatic stress disorder, supranuclear palsy, immune suppression, Alzheimer's disease, gastrointestinal diseases, anorexia nervosa or other feeding disorder, drug addiction, drug or alcohol withdrawal symptoms, inflammatory diseases, cardiovascular or heart-related diseases, fertility problems, human immunodeficiency virus infections, hemorrhagic stress, obesity, infertility, head and spinal cord traumas, epilepsy, stroke, ulcers, amyotrophic lateral sclerosis and hypoglycemia.

[0058] This invention thus further provides a method of treating a subject afflicted with a disorder characterized by CRF overexpression, such as those described hereinabove, which comprises administering to the subject a pharmaceutical composition provided herein. Such compositions generally comprise a therapeutically effective amount of a compound provided herein, that is, an amount effective to ameliorate, lessen or inhibit disorders characterized by CRF overexpression. Such amounts typically comprise from about 0.1 to about 1000 mg of the compound per kg of body weight of the subject to which the composition is administered. Therapeutically effective amounts can be administered according to any dosing regimen satisfactory to those of ordinary skill in the art.

[0059] Administration is, for example, by various parenteral means. Pharmaceutical compositions suitable for parenteral administration include various aqueous media such as aqueous dextrose and saline solutions; glycol solutions are also useful carriers, and preferably contain a water soluble salt of the active ingredient, suitable stabilizing agents, and if necessary, buffer substances. Antioxidizing agents, such as sodium bisulfite, sodium sulfite, or ascorbic acid, either alone or in combination, are suitable stabilizing agents; also used are citric acid and its salts, and EDTA. In addition, parenteral solutions can contain preservatives such as benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.

[0060] Alternatively, compositions can be administered orally in solid dosage forms, such as capsules, tablets and powders; or in liquid forms such as elixirs, syrups, and/or suspensions. Gelatin capsules can be used to contain the active ingredient and a suitable carrier such as but not limited to lactose, starch, magnesium stearate, stearic acid, or cellulose derivatives. Similar diluents can be used to make compressed tablets. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of medication over a period of time. Compressed tablets can be sugar-coated or film-coated to mask any unpleasant taste, or used to protect the active ingredients from the atmosphere, or to allow selective disintegration of the tablet in the gastrointestinal tract.

[0061] This invention is described in the following examples, which those of ordinary skill in the art will readily understand are not limiting on the invention as defined in the claims which follow thereafter.

EXAMPLES

[0062] Table 1 is a brief summary of compounds provided herein, made according to the synthetic schemes described hereinabove and the examples provided hereinbelow.

[0063] Analytical data were recorded for the compounds described below using the following general procedures. Proton NMR spectra were recorded on an Varian FT-NMR (300 MHz); chemical shifts were recorded in ppm (δ) from an internal tetramethysilane standard in deuterochloroform or deuterodimethylsulfoxide as specified below. Mass spectra (MS) or high resolution mass spectra (HRMS) were recorded on a Finnegan MAT 8230 spectrometer (using chemical ionization (CI) with NH3 as the carrier gas or gas chromatography (GC) as specified below) or a Hewlett Packard 5988A model spectrometer. Melting points were recorded on a Buchi Model 510 melting point apparatus and are uncorrected. Boiling points are uncorrected. All pH determinations during workup were made with indicator paper.

[0064] Reagents were purchased from commercial sources and, where necessary, purified prior to use according to the general procedures outlined by D. Perrin and W. L. F. Armarego, Purification of Laboratory Chemicals, 3rd ed., (New York: Pergamon Press, 1988). Chromatography (thin layer (TLC) or preparative) was performed on silica gel using the solvent systems indicated below. For mixed solvent systems, the volume ratios are given. Otherwise, parts and percentages are by weight. 6

TABLE 1
9embedded image
(Ex.)XYZR1R2mp (° C.)
 (1)ClClHEtCH(Me)OHamorph
 (2)ClClHEtCH(Me)OMeoil
 (3)ClClHEtCH(Me)OEtoil
 (4)ClClHEtCH(Et)OH70-71
 (5)ClClHEtCH(Et)OMeoil
 (6)ClClHEtCH(Et)OEtoil
 (7)ClClHEtCH(n-C3H7)OH159-160
 (8)ClClHEtCH(n-C3H7)OMeoil
 (9)ClClHEtCH(n-C3H7)OEt65-67
(10)ClClHEtCH(C≡CMe)OH81-82
(11)ClClHEtCH(C≡CMe)OMeoil
(12)ClClHEtCH(C≡CMe)OEtoil
(13)ClClHEtCH(CPM)OH131-132
(14)ClClHEtCH(CPM)OEtoil
(15)ClClHEtCH(allyl)OEtoil
(16)ClClHEtCH(n-Bu)OHoil
(17)ClClHEtCH(n-Bu)OEtoil
(18)ClClHEtCH[CH(Me)Et]OHamorph.
(19)ClClHEtCH[CH(Me)Et]OEtoil
(20)ClClHMeCH(n-C3H7)OHamorph.
(21)ClClHMeCH(n-C3H7)OEt110-111
(22)ClOMeHEtCH(Et)OH145-146
(23)ClOMeHEtCH(Et)OEtoil
(24)ClOMeHEtCH(n-C3H7)OH152-153
(25)ClOMeHEtCH(n-C3H7)OEtoil
(26)ClOCHF2HEtCH(Et)OH144-145
(27)ClOCHF2HEtCH(Et)OC2H5oil
(28)ClOCHF2HEtCH(n-C3H7)OH123-124
(29)ClOCHF2HEtCH(n-C3H7)OEt67-68
(30)MeOCHF2MeEtCH(n-C3H7)OEt83-84
(31)MeOCHF2HEtCH(n-C3H7)OH147-148
(32)MeOCHF2HEtCH(n-C3H7)OEtoil
(33)ClClHEtC(═O)-n-C3H795-96
(34)ClClHEtC(═CH2)-n-C3H7oil
(35)HClHEtN(Bz)-n-C3H7oil
(36)ClClHEtN(Bz)-n-C3H7oil
(37)ClClHEtNH(Bz)oil
(38)ClClHEtN(Bz)Etoil
(39)ClClHEtN(Et)-n-Buoil
(40)ClClHEtN(allyl)Etoil

Example 1

[0065] 8-(2,4-dichlorophenyl)-2-ethyl-3-(1-hyroxyethyl)imidazo[1,2-a]pyrazine

[0066] Part A: Synthesis of 3-amino-2-chloropyrazine:

[0067] (Ref: S. Okada et al Chem. Pharm. Bull. 1971, 19(7), 1344-1357). A mixture of 2,3-dichloropyrazine (20 g, 0.134 moles) and 28% aq. NH4OH (120 mL) was heated in a resealable pressure tube at 140° C. for 24 h. The solution was cooled and the off-white crystals separated was filtered and dried to afford 16.6 g material (96%, mp 165-166° C.). The crude was quite pure by NMR and used in the next step without purification.

[0068] Part B: Synthesis of 8-chloro-2-ethylimidazo[1,2-a]pyrazine:

[0069] To a solution of 2-amino-3-chloropyrazine (19.5 g, fw=129, 0.15 moles) in dioxane (250.0 mL) was treated with 90% 1-bromo-2-butanone (25 g, fw=151, 1.1 moles, Aldrich) and stirred under nitrogen for 4 h followed by reflux for 48 h. Brick red colored solid separated from the mixture. TLC (1:50 MeOH/CH2Cl2) showed a new spot at Rf=0.30 along with disappearance of starting material spot at Rf=0.42. The reaction mixture was cooled to room temperature filtered the solid and washed the solid with diethyl ether (2×100 mL). NMR of the salt in DMS0-D6 revealed a clean product. The salt was dissolved in water (500 mL), adjusted the pH to 8 using solid Na2CO3, extracted with EtOAc, washed with brine, dried (MgSO4) and concentrated in vacuum to afford pale yellow solid. The crude (20 g, 74% yield, mp 73-74° C.) was found to be quite pure by NMR and used without purification in the next step.

[0070] Part C: Synthesis of 8-(2,4-dichlorophenyl)-2-ethylimidazo[1,2-a]pyrazine:

[0071] A mixture of 8-chloro-2-ethylimidazo[1,2-a]pyrazine (9.05 g, 0.05 mol, fw=181) and 2,4-dichlorobenzeneboronic acid (10.5 g, 0.055 mol, fw=190.81) in toluene (200.0 mL) was treated with 2M aq. Na2CO3 (40.0 mL) and EtOH (20.0 mL). The reaction mixture was degassed under vacuum and purged with nitrogen (repeated 3 times) and then added Pd(PPh3)2Cl2 (740 mg, 0.001 mol, fw=738.18, 2 mol %). After the addition the reaction mixture was degassed under vacuum and purged with nitrogen (repeated 3 times). The resultant mixture was refluxed under nitrogen for 24 h. TLC (1:50 MeOH/CH2Cl2) showed two new spots at Rf=0.53 and 0.35 along with trace amount of starting material spot at Rf=0.30. The reaction mixture was cooled to room temp and partitioned between 200 ml of 1:1 EtOAc/water. The aq. layer was extracted with EtOAc (2×150 mL), dried (MgSO4) and concentrated in vacuum to afford yellow oil. The crude (15.1 g, brown yellow solid) was purified by flash column chromatography on a silica gel using 15% EtOAc/hexane to afford the top spot as pale yellow solid (760 mg, mp 71-72° C.) and characterized as 8-(4-chlorophenyl)-2-ethylimidazo[1,2-a]pyrazine. HRMS calcd. for C14H13N3Cl1: 258.0798. Found: 258.0788 (M+H). Further elution of the column with 30% EtOAc/hexane gave desired product (bottom spot) as white solid (8.6 g, 59% yield, 125-126° C.). HRMS calcd. for C14H12N3Cl2: 292.0408. Found: 292.0409 (M+H).

[0072] Part D: Synthesis of 8-(2,4-dichlorophenyl)-2-ethyl-3-formyl-imidazo[1,2-a]pyrazine:

[0073] POCl3 (99.6 g, 60.0 mL, 65.0 mmol, fw=153.33) was added dropwise to a cooled (0° C.) stirred solution of dry DMF (200 mL). The resultant mixture was stirred for additional 15 min. and then added 8-(2,4-dichlorophenyl)-2-ethylimidazo[1,2-a]pyrazine (14.6 g, 50.0 mmol, fw=292) to the reaction mixture. The reaction mixture was gradually brought to room temperature and stirred for 4 days. The reaction mixture appeared yellow in color. TLC (1:50 MeOH/CH2Cl2) revealed absence of starting material spot (Rf=0.35) and showed a new spot at Rf=0.4. The reaction mixture was quenched with ice (750 g), stirred the mixture for 30 min., neutralized with solid sodium carbonate and extracted with EtOAc (3×200 mL), dried (MgSO4) and concentrated in vacuum to afford yellow solid. The solid was purified by flash column chromatography on a silica gel using 20% EtOAc/hexane to afford 11.7 g (73%, 93-94° C.) of white solid. Anal. calcd. for C15H11Cl2N3O: C, 56.27; H, 3.46; N, 13.12. Found: C, 56.13; H, 3.38; N, 12.96.

[0074] Part E: Synthesis of title compound:

[0075] The aldehyde of Part D of Example 1 (0.320 g, 1.0 mmol) was dissolved in anhydrous THF (5.0 mL) and cooled to #78 C under nitrogen. To this mixture was added dropwise 1.4 M MeMgBr in toluene/THF (3.0 mL, 4.2 mmol) and stirred at −78° C. for 3 h. TLC (1:10 MeOH/CH2Cl2) revealed absence of starting material spot (Rf=0.88) and showed a new spot at Rf=0.12. The reaction mixture was quenched with satd. NH4Cl (10.0 mL), stirred the mixture for 10 min., extracted with EtOAc (3×25 mL), dried (MgSO4) and concentrated in vacuum to afford yellow oil. The residue was purified by flash column chromatography on a silica gel using 2.5% MeOH/CH2Cl2 to afford 207 mg (62%) of amorphous wet white solid. HRMS calcd. for C16H16Cl2N3O: 336.0670. Found: 336.0678 (M+H).

Example 2

[0076] 8-(2,4-dichlorophenyl)-2-ethyl-3-(lmethoxyethyl)imidazo[1,2-a]pyrazine

[0077] The alcohol from Part E of Example 1 (90.0 mg, 0.268 mmol) was dissolved in dry DMF (2.0 mL) under nitrogen. To this mixture was added 60% NaH (21.4 mg, 0.536 mmol, 2 equiv.) and stirred at room temperature for 30 mins. MeI (excess) was added to the mixture and stirred overnight. TLC (1:10 MeOH/CH2Cl2) revealed a new spot (Rf=0.31). The reaction mixture was quenched with water (5.0 mL), stirred the mixture for 10 mins., extracted with EtOAc (3×15 mL), dried (MgSO4) and concentrated in vacuum to afford yellow oil. The residue was purified by flash column chromatography on a silica gel using 1% MeOH/CH2Cl2 to afford yellow oil (32 mg, 34% yield. HRMS calcd. for C17H18Cl2N3O: 350.0827. Found:350.0828 (M+H).

[0078] The compounds of examples 3-32 shown in Table 1 were prepared by following the experimental conditions outlined in Examples 1 & 2, hereinabove.

Example 33

[0079] 8-(2,4-dichlorophenyl)-2-ethyl-3-(1-oxo-butyl)imidazo[1,2-a]pyrazine

[0080] Part A: 8-(2,4-dichlorophenyl)-2-ethyl-3-(1-hydroxybutyl)imidazo[1,2-a]pyrazine:

[0081] The aldehyde (1.6 g, 5.0 mmol, Part D of Example 1) was dissolved in anhydrous THF (25.0 mL) and cooled to −78° C. under nitrogen. To this mixture was added dropwise 2.0 M n-PrMgCl in diethyl ether (6.7 mL, 14.4 mmol) and stirred at −78° C. for 4 h. TLC (1:10 MeOH/CH2Cl2) revealed absence of starting material spot (Rf=0.88) and showed a new spot at Rf=0.05. The reaction mixture was quenched with saturated NH4Cl (30.0 mL), stirred the mixture for 10 min., extracted with EtOAc (3×1O0 mL), dried (MgSO4) and concentrated in vacuum to afford yellow oil. The residue was purified by flash column chromatography on a silica gel using 2.5% MeOH/CH2Cl2 to afford 1.63 g (84%, mp 159-160° C.) of desired product as white solid.

[0082] Part B: Title compound: To a mixture of carbinol (1.1 g, 0.003 moles, fw364, Part A of Example 33) in toluene (25 mL) was added MnO2 and refluxed under nitrogen for 24 h. TLC (1:10 MeOH/CH2Cl2) revealed absence of starting material spot (Rf=0.5) and showed a new spot at Rf=0.86. The reaction mixture was cooled to room temperature, filtered through celite, washed the celite with EtOAc (3×50 mL), and concentrated in vacuum to afford yellow oil. The residue was purified by flash column chromatography on a silica gel using 1% MeOH/CH2Cl2 to afford 580 mg (53%, mp 95-96° C.) of white solid.

Example 34

[0083] 8-(2,4-dichlorophenyl)-2-ethyl-3-(1-propylvinyl)imidazo[1,2-a]pyrazine

[0084] To a solution of keto imidazopyrazine (181 mg, 0.5 mmol, Part B of Example 33) in THF (5.0 mL) at room temp was added 0.5 M toluene solution of the Tebbe reagent (1.2 mL, 0.6 mmol) dropwise under nitrogen atmosphere. The reaction mixture was slightly exothermic during addition and continued stirring for 1 h. TLC (3:7 EtOAc/hexane) revealed absence of starting material (Rf=0.5) along with a new spot (Rf=0.46). The reaction mixture was diluted with 15 mL of Et2O and then added 3-5 drops of 1.0 N Aq. NaOH. After gas evolution ceases, the mixture was filtered through celite, evaporated to dryness and purified by flash column chromatography on a silica gel using 10% EtOAc/hexane to afford yellow oil (81 mg, 45%). HRMS calcd. for C19H20N3Cl2: 360.1034. Found:360.1033

[0085] The compound of example 35 was prepared according to the experimental conditions outlined in Examples 33 and 34, hereinabove

Example 36

[0086] 8-(2,4-dichlorophenyl)-2-ethyl-3-(N-propylbenzylamino) imidazo[1,2-a]pyrazine

[0087] Part A: 3-benzylamino-8-chloro-2-ethylimidazo[1,2-a]pyrazine:

[0088] To a solution of 2-amino-3-chloropyrazine (1.3 g, fw=129, 10.0 mmole) in MeOH (50.0 mL) was treated with propionaldehyde (0.58 g, fw=58, 10.0 mmole, Aldrich), AcOH (1.2 g, 20 mmol, fw=60) and benzyl isocyanide (STENCH, 1.17 g, 10.0 mmol, fw=117.15, Aldrich). The resultant suspension was stirred at room temp overnight. TLC (1:50 MeOH/CH2Cl2) showed a new spot at Rf=0.24 along with unreacted starting material spot at Rf=0.42. The unreacted isocyanide was destroyed by acidifying the reaction mixture to pH 1 using 1N HCl. After acidification the reaction mixture was stirred at room temp for 30 mins, evaporated to dryness, residue dissolved in water, adjusted the pH to 8 using KHCO3, extracted the reaction mixture with EtOAc (3×50 mL) and dried with anhydrous MgSO4. The solvent was evaporated from the reaction mixture and the residue (pale yellow solid) was partitioned between 50 ml of 1:1 EtOAc/aq. NaHCO3. The aq. layer was extracted with EtOAc (2×15 mL), dried (MgSO4) and concentrated in vacuum to afford pale yellow solid (3.0 g). The crude was treated with CH2Cl2 and filtered the white solid (0.75 recovered starting material). The filtrate was evaporated and purified by flash column chromatography on a silica gel using 30% EtOAc/hexane to afford 0.42 g (34% yield) desired product as yellow oil.

[0089] Part B: N-Alkylation: A mixture of 3-benzyamino-8-chloro-2-ethylpyrazine (415 mg, 0.00145 moles, fw=286.45) in DMF (2.0 mL) was treated with 60% NaH (70 mg, 0.00174 moles, 1.2 equiv.) at room temp under nitrogen atmosphere and stirred for 15 mins. To this mixture was added 1-iodopropane (0.296 g, 0.00174 moles, 1.2 equiv.) and stirred at room temp for 4 h. TLC (1:50 MeOH/CH2Cl2) showed a new spot at Rf=0.33 along with several minor spots below the product. Since the starting material spot overlapped with one of the minor spots, the reaction was allowed to continue over weekend. The solvent from the reaction mixture was evaporated under vacuum, quenched with water, extracted with EtOAc (3×10 mL), dried with MgSO4. The solvent from the reaction mixture was evaporated and the crude was purified by flash column chromatography on a silica gel using 15% EtOAc/hexane to afford the desired product as yellow oil (170 mg, 35% yield). HRMS calcd. for C18H22N4Cl1:329.1533. Found: 329.1530 (M+H).

[0090] Part C: Suzuki reaction: A mixture of above chloro compound (0.140 g, 0.43 mmol, fw=328), 2,4-dichlorobenzeneboronic acid (95 mg, 0.65 mmol, fw=190.81) in toluene (5.0 mL) was treated with 2M aq. Na2CO3 (2.0 mL) and EtOH (1 mL). The reaction mixture was degassed under vacuum and purged with nitrogen (repeated 3 times) and then added Pd(PPh3)2Cl2 (18. 5 mg, 0.005 mmol, fw=738.18). After the addition the reaction mixture was degassed under vacuum and purged with nitrogen (repeated 3 times). The resultant mixture was refluxed under nitrogen for 6 h. TLC (1:50 MeOH/CH2Cl2) showed two new spots at Rf=0.75 and 0.5 along with small amount of starting material spot at Rf=0.33. The reaction mixture was cooled to room temp and partitioned between 20 ml of 1:1 EtOAc/water. The aq. layer was extracted with EtOAc (2×15 mL), dried (MgSO4) and concentrated in vacuum to afford yellow oil. The crude was purified by flash column chromatography on a silica gel using 10% EtOAc/hexane to afford the top spot as yellow solid (20 mg). Further elution of the column with 15% EtOAc/hexane gave desired product (bottom spot) as yellow oil (60 mg, 40% yield, 125-126° C.). Also recovered 27.5 mg of unreacted chloropyrazine derivative. Top spot was characterized as mono chloro derivative of Example 35. HRMS calcd. for C24H26N4Cl1:405.1846. Found: 405.1841 (M+H). Bottom spot desired product. HRMS calcd. for C24H25N4Cl2: 439.1456. Found: 439.1455 (M+H).

[0091] The compounds of examples 37 to 40 were prepared by following experimental conditions outlined in Example 36, hereinabove.