US20060154949A1 - Arylindenopyridines and related therapeutic and prophylactic methods - Google Patents

Abstract

This invention provides novel arylindenopyridines of the formula:

and pharmaceutical compositions comprising same, useful for treating disorders ameliorated by antagonizing Adensine A2a receptors or reducing PDE activity in appropriate cells. This invention also provides therapeutic and prophylactic methods using the instant pharmaceutical compositions.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a divisional of co-pending application Ser. No. 10/259,139, filed on Sep. 9, 2002, which is a continuation-in-part of co-pending application Ser. No.10/123,389, filed on Apr. 16, 2002, which claims the benefit of provisional application Ser. No. 60/284,465 filed on Apr. 18, 2001, which are incorporated herein by reference.
FIELD OF THE INVENTION
• This invention relates to novel arylindenopyridines and their therapeutic and prophylactic uses. Disorders treated and/or prevented using these compounds include neurodegenerative and movement disorders ameliorated by antagonizing Adenosine A2a receptors and inflammatory and AIDS-related disorders ameliorated by inhibiting phosphodiesterace activity.
BACKGROUND OF THE INVENTION
• Adenosine A2a Receptors
• Adenosine is a purine nucleotide produced by all metabolically active cells within the body. Adenosine exerts its effects via four subtypes of cell-surface receptors (A1, A2a, A2b and A3), which belong to the G protein coupled receptor superfamily (Stiles, G. L. Journal of Biological Chemistry, 1992, 267, 6451). A1 and A3 couple to inhibitory G protein, while A2a and A2b couple to stimulatory G protein. A2a receptors are mainly found in the brain, both in neurons and glial cells (highest level in the striatum and nucleus accumbens, moderate to high level in olfactory tubercle, hypothalamus, and hippocampus etc. regions) (Rosin, D. L.; Robeva, A.; Woodard, R. L.; Guyenet, P. G.; Linden, J. Journal of Comparative Neurology, 1998, 401, 163).
• In peripheral tissues, A2a receptors are found in platelets, neutrophils, vascular smooth muscle and endothelium (Gessi, S.; Varani, K.; Merighi, S.; Ongini, E.; Borea, P. A. British Journal of Pharmacology, 2000, 129, 2). The striatum is the main brain region for the regulation of motor activity, particularly through its innervation from dopaminergic neurons originating in the substantia nigra. The striatum is the major target of the dopaminergic neuron degeneration in patients with Parkinson's Disease (PD). Within the striatum, A2a receptors are co-localized with dopamine D2 receptors, suggesting an important site of for the integration of adenosine and dopamine signaling in the brain (Fink, J. S.; Weaver, D. R.; Rivkees, S. A.; Peterfreund, R. A.; Pollack, A. E.; Adler, E. M.; Reppert, S. M. Brain Research Molecular Brain Research, 1992, 14, 186).
• Neurochemical studies have shown that activation of A2a receptors reduces the binding affinity of D2 agonist to their receptors. This D2R and A2aR receptor-receptor interaction has been demonstrated in striatal membrane preparations of rats (Ferre, S.; von Euler, G.; Johansson, B.; Fredholm, B. B.; Fuxe, K. Proceedings of the National Academy of Sciences of the United States of America, 1991, 88, 7238) as well as in fibroblast cell lines after transfected with A2aR and D2R cDNAs (Salim, H.; Ferre, S.; Dalal, A.; Peterfreund, R. A.; Fuxe, K.; Vincent, J. D.; Lledo, P. M. Journal of Neurochemistry, 2000, 74, 432). In vivo, pharmacological blockade of A2a receptors using A2a antagonist leads to beneficial effects in dopaminergic neurotoxin MPTP(1-methyl-4-pheny-1,2,3,6-tetrahydropyridine)-induced PD in various species, including mice, rats, and monkeys (Ikeda, K.; Kurokawa, M.; Aoyama, S.; Kuwana, Y. Journal of Neurochemistry, 2002, 80, 262). Furthermore, A2a knockout mice with genetic blockade of A2a function have been found to be less sensitive to motor impairment and neurochemical changes when they were exposed to neurotoxin MPTP (Chen, J. F.; Xu, K.; Petzer, J. P.; Staal, R.; Xu, Y. H.; Beilstein, M.; Sonsalla, P. K.; Castagnoli, K.; Castagnoli, N., Jr.; Schwarzschild, M. A. Journal of Neuroscience, 2001, 21, RC143).
• In humans, the adenosine receptor antagonist theophylline has been found to produce beneficial effects in PD patients (Mally, J.; Stone, T. W. Journal of the Neurological Sciences, 1995, 132, 129). Consistently, recent epidemiological study has shown that high caffeine consumption makes people less likely to develop PD (Ascherio, A.; Zhang, S. M.; Hernan, M. A.; Kawachi, I.; Colditz, G. A.; Speizer, F. E.; Willett, W. C. Annals of Neurology, 2001, 50, 56). In summary, adenosine A2a receptor blockers may provide a new class of antiparkinsonian agents (Impagnatiello, F.; Bastia, E.; Ongini, E.; Monopoli, A. Emerging Therapeutic Targets, 2000, 4, 635).
• Phosphodiesterase Inhibitors
• There are eleven known families of phosphodiesterases (PDE) widely distributed in many cell types and tissues. In their nomenclature, the number indicating the family is followed by a capital letter that indicates a distinct gene. A PDE inhibitor increases the concentration of cAMP in tissue cells, and hence, is useful in the prophylaxis or treatment of various diseases caused by the decrease in cAMP level which is induced by the abnormal metabolism of cAMP. These diseases include conditions such as hypersensitivity, allergy, arthritis, asthma, bee sting, animal bite, bronchospasm, dysmenorrhea, esophageal spasm, glaucoma, premature labor, a urinary tract disorder, inflammatory bowel disease, stroke, erectile dysfunction, HIV/AIDS, cardiovascular disease, gastrointestinal motility disorder, and psoriasis.
• Among known phosphodiesterases today, PDE1 family are activated by calcium-calmodulin; its members include PDE1A and PDE1B, which preferentially hydrolyze cGMP, and PDE1C which exhibits a high affinity for both cAMP and cGMP. PDE2 family is characterized as being specifically stimulated by cGMP. PDE2A is specifically inhibited by erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA). Enzymes in the PDE3 family (e.g. PDE3A, PDE3B) are specifically inhibited by cGMP. PDE4 (e.g. PDE4A, PDE4B, PDE4C, PDE4D) is a cAMP specific PDE present in T-cells, which is involved in inflammatory responses. A PDE3 and/or PDE4 inhibitor would be predicted to have utility in the following disorders: autoimmune disorders (e.g. arthritis), inflammatory bowel disease, bronchial disorders (e.g. asthma), HIV/AIDS, and psoriasis. A PDE5 (e.g. PDE5A) inhibitor would be useful for the treatment of the following disorders: cardiovascular disease and erectile dysfunction. The photoreceptor PDE6 (e.g. PDE6A, PDE6B, PDE6C) enzymes specifically hydrolyze cGMP. PDE8 family exhibits high affinity for hydrolysis of both cAMP and cGMP but relatively low sensitivity to enzyme inhibitors specific for other PDE families.
• Phosphodiesterase 7 (PDE7A, PDE7B) is a cyclic nucleotide phosphodiesterase that is specific for cyclic adenosine monophosphate (cAMP). PDE7 catalyzes the conversion of cAMP to adenosine monophosphate (AMP) by hydrolyzing the 3′-phosphodiester bond of cAMP. By regulating this conversion, PDE7 allows for non-uniform intracellular distribution of cAMP and thus controls the activation of distinct kinase signalling pathways. PDE7A is primarily expressed in T-cells, and it has been shown that induction of PDE7A is required for T-cell activation (Li, L.; Yee, C.; Beavo, J. A. Science 1999, 283, 848). Since PDE7A activation is necessary for T-cell activation, small molecule inhibitors of PDE7 would be useful as immunosuppressants. An inhibitor of PDE7A would be predicted to have immunosuppressive effects with utility in therapeutic areas such as organ transplantation, autoimmune disorders (e.g. arthritis), HIV/AIDS, inflammatory bowel disease, asthma, allergies and psoriasis.
• Few potent inhibitors of PDE7 have been reported. Most inhibitors of other phosphodiesterases have IC₅₀'s for PDE7 in the 100 μM range. Recently, Martinez, et al. (J. Med. Chem. 2000, 43, 683) reported a series of PDE7 inhibitors, among which the two best compounds have PDE7 IC₅₀'s of 8 and 13 μM. However, these compounds were only 2-3 times selective for PDE7 over PDE4 and PDE3.
• Finally, the following compounds have been disclosed, and some of them are reported to show antimicrobial activity against strains such as Plasmodium falciparum, Candida albicans and Staphylococcus aureus (Gorlitzer, K.; Herbig, S.; Walter, R. D. Pharmazie 1997, 504):

  
SUMMARY OF THE INVENTION
• This invention provides a compound having the structure of Formula I

  
• or a pharmaceutically acceptable salt thereof, wherein
• • (a) R₁ is selected from the group consisting of:
    • (i) —COR₅, wherein R₅ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;
    •  wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁ are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;
    • (ii) COOR₆, wherein R₆ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;
    •  wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁ are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C₃-₇ cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;
    • (iii) cyano;
    • (iv) a lactone or lactam formed with R₄;
    • (v) —CONR₇R₈ wherein R₇ and R₈ are independently selected from H, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, trifluoromethyl, hydroxy, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl;
      • wherein the alkyl, cycloalkyl, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl groups may be substituted with carboxyl, alkyl, aryl, substituted aryl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, hydroxamic acid, sulfonamide, sulfonyl, hydroxy, thiol, alkoxy or arylalkyl,
    •  or R₇ and R₈ taken together with the nitrogen to which they are attached form a heterocycle or heteroaryl group;
    • (vi) a carboxylic ester or carboxylic acid bioisostere including optionally substituted heteroaryl groups
  • (b) R₂ is selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl and optionally substituted C_3-7 cycloalkyl;
  • (c) R₃ is from one to four groups independently selected from the group consisting of:
    • (i) hydrogen, halo, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, aryl, heteroaryl, and heterocyclyl;
    • (ii) —NR₁₀R₁₁ wherein R₁₀ and R₁₁ are independently selected from H, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, carboxyalkyl, aryl, heteroaryl, and heterocyclyl or R₁₀ and R₁₁ taken together with the nitrogen form a heteroaryl or heterocyclyl group;
    • (iii) —NR₁₂COR₁₃ wherein R₁₂ is selected from hydrogen or alkyl and R₁₃ is selected from hydrogen, alkyl, substituted alkyl, C_1-3alkoxyl, carboxyalkyl, R₃₀R₃₁N (CH₂)_p—, R₃₀R₃₁NCO(CH₂)_p—, aryl, arylalkyl, heteroaryl and heterocyclyl or R₁₂ and R₁₃ taken together with the carbonyl form a carbonyl containing heterocyclyl group, wherein, R₃₀ and R₃₁ are independently selected from H, OH, alkyl, and alkoxy, and p is an integer from 1-6, wherein the alkyl group may be substituted with carboxyl, alkyl, aryl, substituted aryl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, hydroxamic acid, sulfonamide, sulfonyl, hydroxy, thiol, alkoxy or arylalkyl;
  • (d) R₄ is selected from the group consisting of (i) hydrogen, (ii) C_1-3 straight or branched chain alkyl, (iii) benzyl and (iv) —NR₁₃R₁₄, wherein R₁₃ and R₁₄ are independently selected from hydrogen and C_1-6 alkyl;
  •  wherein the C_1-3alkyl and benzyl groups are optionally substituted with one or more groups selected from C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, amino, NR₁₃R₁₄, aryl and heteroaryl; and
  • (e) X is selected from S and O;
• with the proviso that when R₄ is isopropyl, then R₃ is not halogen.
• In an alternative embodiment, the invention is directed to compounds of Formula I wherein R₁, R₃ and R₄ are as described above and R₂ is —NR₁₅R₁₆ wherein R₁₅ and R₁₆ are independently selected from hydrogen, optionally substituted C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, aryl, heteroaryl, and heterocyclyl or R₁₅ and R₁₆ taken together with the nitrogen form a heteroaryl or heterocyclyl group; with the proviso that when R₂ is NHR₁₆, R₁ is not —COOR₆ where R₆ is ethyl.
• This invention also provides a pharmaceutical composition comprising the instant compound and a pharmaceutically acceptable carrier.
• This invention further provides a method of treating a subject having a condition ameliorated by antagonizing Adenosine A2a receptors or by reducing PDE activity in appropriate cells, which comprises administering to the subject a therapeutically effective dose of the instant pharmaceutical composition.
• This invention further provides a method of preventing a disorder ameliorated by antagonizing Adenosine A2a receptors or by reducing PDE activity in appropriate cells in a subject, comprising administering to the subject a prophylactically effective dose of the compound of claim 1 either preceding or subsequent to an event anticipated to cause a disorder ameliorated by antagonizing Adenosine A2a receptors or reducing PDE activity in appropriate cells in the subject.
DETAILED DESCRIPTION OF THE INVENTION
• Compounds of Formula 1 are potent small molecule antagonists of the Adenosine A2a receptors that have demonstrated potency for the antagonism of Adenosine A2a, A1, and A3 receptors.
• Compounds of Formula I are also potent small molecule phosphodiesterase inhibitors that have demonstrated potency for inhibition of PDE7, PDE5, and PDE4. Some of the compounds of this invention are potent small molecule PDE7 inhibitors which have also demonstrated good selectivity against PDE5 and PDE4.
• Preferred embodiments for R₁ are COOR₆, wherein R₆ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl. Preferably R₆ is H, or C_1-8 straight or branched chain alkyl which may be optionally substituted with a substituent selected from CN and hydroxy.
• Preferred embodiments for R₂ are optionally substituted heterocycle, optionally substituted aryl and optionally substituted heteroaryl. Preferred substituents are from one to three members selected from the group consisting of halogen, alkyl, alkoxy, alkoxyphenyl, halo, triflouromethyl, trifluoro or difluoromethoxy, amino, alkylamino, hydroxy, cyano, and nitro. Preferably, R₂ is optionally substituted furan, phenyl or napthyl or R₂ is

  

  
  optionally substituted with from one to three members selected from the group consisting of halogen, alkyl, hydroxy, cyano, and nitro. In another embodiment of the instant compound, R₂ is —NR₁₅R₁₆.
• Preferred substituents for R₃ include:
• • • (i) hydrogen, halo, C_1-8 straight or branched chain alkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, and hydroxy;
    • (ii) —NR₁₀R₁₁ wherein R₁₀and R₁₁ are independently selected from H, C_1-8 straight or branched chain alkyl, arylC_1-8alkyl, C_3-7 cycloalkyl, carboxyC_1-8alkyl, aryl, heteroaryl, and heterocyclyl or R₁₀ and R₁₁ taken together with the nitrogen form a heteroaryl or heterocyclyl group;
    • (iii) —NR₁₂COR₁₃ wherein R₁₂ is selected from hydrogen or alkyl and R₁₃ is selected from hydrogen, alkyl, substituted alkyl, C_1-3alkoxyl, carboxyC_1-8alkyl, aryl, arylalkyl, R₃₀R₃₁N (CH₂)_p—, R₃₀R₃₁NCO(CH₂)_p—, heteroaryl and heterocyclyl or R₁₂ and R₁₃ taken together with the carbonyl form a carbonyl containing heterocyclyl group, wherein , R₃₀ and R₃₁ are independently selected from H, OH, alkyl, and alkoxy, and p is an integer from 1-6.
• Particularly, R₃ is selected from the group consisting of

  
• Preferred embodiments for R₄ include hydrogen, C_1-3 straight or branched chain alkyl, particularly methyl, amine and amino.
• In a further embodiment of the instant compound, R₁ is COOR₆ and R₂ is selected from the group consisting of substituted phenyl, and substituted naphthyl or R₂ is NR₁₅R₁₆.
• More particularly, R₁ is COOR₆ where R₆ is alkyl, R₂ is substituted phenyl or naphthyl or R₂ is NR₁₅R₁₆, and R₃ is selected from the group consisting of H, nitro, amino, NHAc, halo, hydroxy, alkoxy, or a moiety of the formulae:

  

  
  , alkyl(CO)NH—, and R₄ is selected from hydrogen, C_1-3 straight or branched chain alkyl, particularly methyl, and amino.
• In a preferred embodiment, the compound is selected from the group of compounds shown in Table 1 hereinafter.
• More preferably, the compound is selected from the following compounds:

  
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 2-amino-4-(1,3-benzodioxol-5-yl)-5-oxo-, ethyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(6-bromo-1,3-benzodioxol-5-yl)-2-methyl-5-oxo-, ethyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 7-amino-4-(1,3-benzodioxol-5-yl)-2-methyl-5-oxo-, ethyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(6-bromo-1,3-benzodioxol-5-yl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 8-(acetylamino)-4-(1,3-benzodioxol-5-yl)-2-methyl-5-oxo-, ethyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 2-methyl-4-(3-methylphenyl)-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 7-amino-4-(3,5-dimethylphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 7-amino-2-methyl-4-(4-methyl-1-naphthalenyl)-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dibromo-4-hydroxyphenyl)-2-methyl-8-nitro-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 7,8-dichloro-4-(3,5-dibromo-4-hydroxyphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 7-bromo-4-(3,5-dibromo-4-hydroxyphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 8-bromo-4-(3,5-dibromo-4-hydroxyphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 8-[(3-carboxy-1-oxopropyl)amino]-4-(3,5-dimethylphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 8-[(3-carboxy-1-oxopropyl)amino]-2-methyl-4-(4-methyl-1-naphthalenyl)-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-8-[[4-(hydroxyamino)-1,4-dioxobutyl]amino]-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-8-[[[(2-hydroxyethyl)amino]acetyl]amino]-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 8-[(4-carboxy-1-oxobutyl)amino]-4-(3,5-dimethylphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-8-[[[(2-hydroxyethyl)methylamino]acetyl]amino]-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-2-methyl-8-[(4-morpholinylacetyl)amino]-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3,5-dimethylphenyl)-2-methyl-5-oxo-8-[(1-piperazinylacetyl)amino]-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-phenyl-2-amino-5-oxo-, ethyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(4-methylphenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3-bromophenyl)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3-bromophenylamino)-2-methyl-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-phenyl-2-amino-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(2-furyl)-2-amino-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(3-furyl)-2-amino-5-oxo-, methyl ester
• 
5H-indeno[1,2-b]pyridine-3-carboxylic acid, 4-(2-furyl)-2-amino-5-oxo-, ethyl ester
• The instant compounds can be isolated and used as free bases. They can also be isolated and used as pharmaceutically acceptable salts. Examples of such salts include hydrobromic, hydroiodic, hydrochloric, perchloric, sulfuric, maleic, fumaric, malic, tartaric, citric, benzoic, mandelic, methanesulfonic, hydroethanesulfonic, benzenesulfonic, oxalic, palmoic, 2-naphthalenesulfonic, p-toluenesulfonic, cyclohexanesulfamic and saccharic.
• This invention also provides a pharmaceutical composition comprising the instant compound and a pharmaceutically acceptable carrier.
• Pharmaceutically acceptable carriers are well known to those skilled in the art and include, but are not limited to, from about 0.01 to about 0.1 M and preferably 0.05 M phosphate buffer or 0.8% saline. Such pharmaceutically acceptable carriers can be aqueous or non-aqueous solutions, suspensions and emulsions. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and injectable organic esters such as ethyl oleate. Aqueous carriers include water, ethanol, alcoholic/aqueous solutions, glycerol, emulsions or suspensions, including saline and buffered media. Oral carriers can be elixirs, syrups, capsules, tablets and the like. The typical solid carrier is an inert substance such as lactose, starch, glucose, methyl-cellulose, magnesium stearate, dicalcium phosphate, mannitol and the like. Parenteral carriers include sodium chloride solution, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's and fixed oils. Intravenous carriers include fluid and nutrient replenishers, electrolyte replenishers such as those based on Ringer's dextrose and the like. Preservatives and other additives can also be present, such as, for example, antimicrobials, antioxidants, chelating agents, inert gases and the like. All carriers can be mixed as needed with disintegrants, diluents, granulating agents, lubricants, binders and the like using conventional techniques known in the art.
• This invention further provides a method of treating a subject having a condition ameliorated by antagonizing Adenosine A2a receptors or by reducing PDE activity in appropriate cells, which comprises administering to the subject a therapeutically effective dose of the instant pharmaceutical composition.
• In one embodiment, the disorder is a neurodegenerative or movement disorder. In another embodiment, the disorder is an inflammatory disorder. In still another embodiment, the disorder is an AIDS-related disorder. Examples of disorders treatable by the instant pharmaceutical composition include, without limitation, Parkinson's Disease, Huntington's Disease, Multiple System Atrophy, Corticobasal Degeneration, Alzheimer's Disease, Senile Dementia, organ transplantation, autoimmune disorders (e.g. arthritis), immune challenge such as a bee sting, inflammatory bowel disease, bronchial disorders (e.g. asthma), HIV/AIDS, cardiovascular disorder, erectile dysfunction, allergies, and psoriasis.
• In one preferred embodiment, the disorder is rheumatoid arthritis.
• In another preferred embodiment, the disorder is Parkinson's disease.
• As used herein, the term “subject” includes, without limitation, any animal or artificially modified animal having a disorder ameliorated by reducing PDE activity in appropriate cells. In a preferred embodiment, the subject is a human. In a more preferred embodiment, the subject is a human.
• As used herein, “appropriate cells” include, by way of example, cells which display PDE activity. Specific examples of appropriate cells include, without limitation, T-lymphocytes, muscle cells, neuro cells, adipose tissue cells, monocytes, macrophages, fibroblasts.
• Administering the instant pharmaceutical composition can be effected or performed using any of the various methods known to those skilled in the art. The instant compounds can be administered, for example, intravenously, intramuscularly, orally and subcutaneously. In the preferred embodiment, the instant pharmaceutical composition is administered orally. Additionally, administration can comprise giving the subject a plurality of dosages over a suitable period of time. Such administration regimens can be determined according to routine methods.
• As used herein, a “therapeutically effective dose” of a pharmaceutical composition is an amount sufficient to stop, reverse or reduce the progression of a disorder. A “prophylactically effective dose” of a pharmaceutical composition is an amount sufficient to prevent a disorder, i.e., eliminate, ameliorate and/or delay the disorder's onset. Methods are known in the art for determining therapeutically and prophylactically effective doses for the instant pharmaceutical composition. The effective dose for administering the pharmaceutical composition to a human, for example, can be determined mathematically from the results of animal studies.
• In one embodiment, the therapeutically and/or prophylactically effective dose is a dose sufficient to deliver from about 0.001 mg/kg of body weight to about 200 mg/kg of body weight of the instant pharmaceutical composition. In another embodiment, the therapeutically and/or prophylactically effective dose is a dose sufficient to deliver from about 0.05 mg/kg of body weight to about 50 mg/kg of body weight. More specifically, in one embodiment, oral doses range from about 0.05 mg/kg to about 100 mg/kg daily. In another embodiment, oral doses range from about 0.05 mg/kg to about 50 mg/kg daily, and in a further embodiment, from about 0.05 mg/kg to about 20 mg/kg daily. In yet another embodiment, infusion doses range from about 1.0 μg/kg/min to about 10 mg/kg/min of inhibitor, admixed with a pharmaceutical carrier over a period ranging from about several minutes to about several days. In a further embodiment, for topical administration, the instant compound can be combined with a pharmaceutical carrier at a drug/carrier ratio of from about 0.001 to about 0.1.
• This invention still further provides a method of preventing an inflammatory response in a subject, comprising administering to the subject a prophylactically effective amount of the instant pharmaceutical composition either preceding or subsequent to an event anticipated to cause the inflammatory response in the subject. In the preferred embodiment, the event is an insect sting or an animal bite.
• Definitions and Nomenclature
• Unless otherwise noted, under standard nomenclature used throughout this disclosure the terminal portion of the designated side chain is described first, followed by the adjacent functionality toward the point of attachment.
• As used herein, the following chemical terms shall have the meanings as set forth in the following paragraphs: “independently”, when in reference to chemical substituents, shall mean that when more than one substituent exists, the substituents may be the same or different.
• “Alkyl” shall mean straight, cyclic and branched-chain alkyl. Unless otherwise stated, the alkyl group will contain 1-20 carbon atoms. Unless otherwise stated, the alkyl group may be optionally substituted with one or more groups such as halogen, OH, CN, mercapto, nitro, amino, C₁-C₈-alkyl, C₁-C₈-alkoxyl, C₁-C₈-alkylthio, C₁-C₈-alkyl-amino, di(C₁-C₈-alkyl)amino, (mono-, di-, tri-, and per-) halo-alkyl, formyl, carboxy, alkoxycarbonyl, C₁-C₈-alkyl-CO—O—, C₁-C₈-alkyl-CO—NH—, carboxamide, hydroxamic acid, sulfonamide, sulfonyl, thiol, aryl, aryl(c₁-c₈)alkyl, heterocyclyl, and heteroaryl.
• “Alkoxy” shall mean —O-alkyl and unless otherwise stated, it will have 1-8 carbon atoms.
• The term “bioisostere” is defined as “groups or molecules which have chemical and physical properties producing broadly similar biological properties.” (Burger's Medicinal Chemistry and Drug Discovery, M. E. Wolff, ed. Fifth Edition, Vol. 1, 1995, Pg. 785).
• “Halogen” shall mean fluorine, chlorine, bromine or iodine; “PH” or “Ph” shall mean phenyl; “Ac” shall mean acyl; “Bn” shall mean benzyl.
• The term “acyl” as used herein, whether used alone or as part of a substituent group, means an organic radical having 2 to 6 carbon atoms (branched or straight chain) derived from an organic acid by removal of the hydroxyl group. The term “Ac” as used herein, whether used alone or as part of a substituent group, means acetyl.
• “Aryl” or “Ar,” whether used alone or as part of a substituent group, is a carbocyclic aromatic radical including, but not limited to, phenyl, 1- or 2-naphthyl and the like. The carbocyclic aromatic radical may be substituted by independent replacement of 1 to 5 of the hydrogen atoms thereon with halogen, OH, CN, mercapto, nitro, amino, C₁-C₈-alkyl, C₁-C₈-alkoxyl, C₁-C₈-alkylthio, C₁-C₈-alkyl-amino, di(C₁-C₈-alkyl)amino, (mono-, di-, tri-, and per-) halo-alkyl, formyl, carboxy, alkoxycarbonyl, C₁-C₈-alkyl-CO—O—, C₁-C₈-alkyl-CO—NH—, or carboxamide. Illustrative aryl radicals include, for example, phenyl, naphthyl, biphenyl, fluorophenyl, difluorophenyl, benzyl, benzoyloxyphenyl, carboethoxyphenyl, acetylphenyl, ethoxyphenyl, phenoxyphenyl, hydroxyphenyl, carboxyphenyl, trifluoromethylphenyl, methoxyethylphenyl, acetamidophenyl, tolyl, xylyl, dimethylcarbamylphenyl and the like. “Ph” or “PH” denotes phenyl.
• Whether used alone or as part of a substituent group, “heteroaryl” refers to a cyclic, fully unsaturated radical having from five to ten ring atoms of which one ring atom is selected from S, O, and N; 0-2 ring atoms are additional heteroatoms independently selected from S, O, and N; and the remaining ring atoms are carbon. The radical may be joined to the rest of the molecule via any of the ring atoms. Exemplary heteroaryl groups include, for example, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrroyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isoxazolyl, thiadiazolyl, triazolyl, triazinyl, oxadiazolyl, thienyl, furanyl, quinolinyl, isoquinolinyl, indolyl, isothiazolyl, 2-oxazepinyl, azepinyl, N-oxo-pyridyl, 1-dioxothienyl, benzothiazolyl, benzoxazolyl, benzothienyl, quinolinyl-N-oxide, benzimidazolyl, benzopyranyl, benzisothiazolyl, benzisoxazolyl, benzodiazinyl, benzofurazanyl, benzothiopyranyl, indazolyl, indolizinyl, benzofuryl, chromonyl, coumarinyl, cinnolinyl, quinoxalinyl, indazolyl, pyrrolopyridinyl, furopyridinyl (such as furo[2,3-c]pyridinyl, furo[3,2-b]pyridinyl, or furo[2,3-b]pyridinyl), imidazopyridinyl (such as imidazo[4,5-b]pyridinyl or imidazo[4,5-c]pyridinyl), naphthyridinyl, phthalazinyl, purinyl, pyridopyridyl, quinazolinyl, thienofuryl, thienopyridyl, thienothienyl, and furyl. The heteroaryl group may be substituted by independent replacement of 1 to 5 of the hydrogen atoms thereon with halogen, OH, CN, mercapto, nitro, amino, C₁-C₈-alkyl, C₁-C₈-alkoxyl, C₁-C₈-alkylthio, C₁-C₈-alkyl-amino, di(C₁-C₈-alkyl)amino, (mono-, di-, tri-, and per-) halo-alkyl, formyl, carboxy, alkoxycarbonyl, C₁-C₈-alkyl-CO—O—, C₁-C₈-alkyl-CO—NH—, or carboxamide. Heteroaryl may be substituted with a mono-oxo to give for example a 4-oxo-1H-quinoline.
• The terms “heterocycle,” “heterocyclic,” and “heterocycle” refer to an optionally substituted, fully or partially saturated cyclic group which is, for example, a 4- to 7-membered monocyclic, 7- to 11 -membered bicyclic, or 10- to 15-membered tricyclic ring system, which has at least one heteroatom in at least one carbon atom containing ring. Each ring of the heterocyclic group containing a heteroatom may have 1, 2, or 3 heteroatoms selected from nitrogen atoms, oxygen atoms, and sulfur atoms, where the nitrogen and sulfur heteroatoms may also optionally be oxidized. The nitrogen atoms may optionally be quaternized. The heterocyclic group may be attached at any heteroatom or carbon atom.
• Exemplary monocyclic heterocyclic groups include pyrrolidinyl; oxetanyl; pyrazolinyl; imidazolinyl; imidazolidinyl; oxazolyl; oxazolidinyl; isoxazolinyl; thiazolidinyl; isothiazolidinyl; tetrahydrofuryl; piperidinyl; piperazinyl; 2-oxopiperazinyl; 2-oxopiperidinyl; 2-oxopyrrolidinyl; 4-piperidonyl; tetrahydropyranyl; tetrahydrothiopyranyl; tetrahydrothiopyranyl sulfone; morpholinyl; thiomorpholinyl; thiomorpholinyl sulfoxide; thiomorpholinyl sulfone; 1,3-dioxolane; dioxanyl; thietanyl; thiiranyl; and the like. Exemplary bicyclic heterocyclic groups include quinuclidinyl; tetrahydroisoquinolinyl; dihydroisoindolyl; dihydroquinazolinyl (such as 3,4-dihydro-4-oxo-quinazolinyl); dihydrobenzofuryl; dihydrobenzothienyl; dihydrobenzothiopyranyl; dihydrobenzothiopyranyl sulfone; dihydrobenzopyranyl; indolinyl; isochromanyl; isoindolinyl; piperonyl; tetrahydroquinolinyl; and the like.
• Substituted aryl, substituted heteroaryl, and substituted heterocycle may also be substituted with a second substituted-aryl, a second substituted-heteroaryl, or a second substituted-heterocycle to give, for example, a 4-pyrazol-1-yl-phenyl or 4-pyridin-2-yl-phenyl.
• Designated numbers of carbon atoms (e.g., C_1-8) shall refer independently to the number of carbon atoms in an alkyl or cycloalkyl moiety or to the alkyl portion of a larger substituent in which alkyl appears as its prefix root.
• Unless specified otherwise, it is intended that the definition of any substituent or variable at a particular location in a molecule be independent of its definitions elsewhere in that molecule. It is understood that substituents and substitution patterns on the compounds of this invention can be selected by one of ordinary skill in the art to provide compounds that are chemically stable and that can be readily synthesized by techniques known in the art as well as those methods set forth herein.
• Where the compounds according to this invention have at least one stereogenic center, they may accordingly exist as enantiomers. Where the compounds possess two or more stereogenic centers, they may additionally exist as diastereomers. Furthermore, some of the crystalline forms for the compounds may exist as polymorphs and as such are intended to be included in the present invention. In addition, some of the compounds may form solvates with water (i.e., hydrates) or common organic solvents, and such solvates are also intended to be encompassed within the scope of this invention.
• Some of the compounds of the present invention may have trans and cis isomers. In addition, where the processes for the preparation of the compounds according to the invention give rise to mixture of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. The compounds may be prepared as a single stereoisomer or in racemic form as a mixture of some possible stereoisomers. The non-racemic forms may be obtained by either synthesis or resolution. The compounds may, for example, be resolved into their components enantiomers by standard techniques, such as the formation of diastereomeric pairs by salt formation. The compounds may also be resolved by covalent linkage to a chiral auxiliary, followed by chromatographic separation and/or crystallographic separation, and removal of the chiral auxiliary. Alternatively, the compounds may be resolved using chiral chromatography.
• This invention will be better understood by reference to the Experimental Details which follow, but those skilled in the art will readily appreciate that these are only illustrative of the invention as described more fully in the claims which follow thereafter. Additionally, throughout this application, various publications are cited. The disclosure of these publications is hereby incorporated by reference into this application to describe more fully the state of the art to which this invention pertains.
• Experimental Details
• I. General Synthetic Schemes
• Representative compounds of the present invention can be synthesized in accordance with the general synthetic methods described below and illustrated in the following general schemes. The products of some schemes can be used as intermediates to produce more than one of the instant compounds. The choice of intermediates to be used to produce subsequent compounds of the present invention is a matter of discretion that is well within the capabilities of those skilled in the art.

  
• Procedures described in Scheme 1, wherein R_3a, R_3b, R_3c, and R_3d are independently any R₃ group, and R₁, R₂, R₃, and R₄ are as described above, can be used to prepare compounds of the invention wherein X is O.
• Benzylidenes 2 may be obtained by known methods (Bullington, J. L; Cameron, J. C.; Davis, J. E.; Dodd, J. H.; Harris, C. A.; Henry, J. R.; Pellegrino-Gensey, J. L.; Rupert, K. C.; Siekierka, J. J. Bioorg. Med. Chem. Lett. 1998, 8, 2489; Petrow, V.; Saper, J.; Sturgeon, B. J. Chem. Soc. 1949, 2134). Hantzsch reaction of the benzylidene compounds with enamines 3 can be performed in refluxing acetic acid (Petrow et al., supra). When the desired enamines are not available, alternate Hantzsch conditions may be utilized which involve adding ammonium acetate to the reaction. The resulting dihydropyridines 4 are oxidized with chromium trioxide to obtain the desired pyridines 1 (Petrow et al., supra). In cases where the substitution pattern on the fused aromatic ring (R₃) leads to a mixture of regioisomers, the products can be separated by column chromatography.
• In some cases, especially where R₂ is an alkyl group, another modification of the Hantzsch may be performed which uses three components (Bocker, R. H.; Buengerich, P. J. Med. Chem. 1986, 29, 1596). Where R₂ is an alkyl group it is also necessary to perform the oxidation with DDQ or MnO₂ instead of chromium (VI) oxide (Vanden Eynde, J. J.; Delfosse, F.; Mayence, A.; Van Haverbeke, Y. Tetrahedron 1995, 51, 6511).

  
• In order to obtain the corresponding carboxylic acids and amides, the cyanoethyl esters 5 are prepared as described above. The esters are converted to the carboxylic acids by treatment with sodium hydroxide in acetone and water (Ogawa, T.; Matsumoto, K.; Yokoo, C.; Hatayama, K.; Kitamura, K. J. Chem. Soc., Perkin Trans. 1 1993, 525). The corresponding amides can then be obtained from the acids using standard means.

  
• The procedure for making compounds where R₄ is NH₂ may be slightly modified. These compounds are prepared in one step from the benzylidenes 2 and alkyl amidinoacetate (Kobayashi, T.; Inoue, T.; Kita, Z.; Yoshiya, H.; Nishino, S.; Oizumi, K.; Kimura, T. Chem. Pharm. Bull. 1995, 43, 788) as depicted in Scheme 4 wherein R is R₅ or R₆ as described above.

  
• The dihydropyridine lactones 9 can be synthesized from benzylidenes 8 (Zimmer, H.; Hillstrom, W. W.; Schmidt, J. C.; Seemuth, P. D.; Vogeli, R. J. Org. Chem. 1978, 43, 1541) and 1,3-indanedione, as shown in Scheme 5, and the corresponding pyridine is then obtained by oxidation with manganese dioxide.

  
• Representative schemes to modify substituents on the fused aromatic ring are shown below. The amines 11 are obtained from the corresponding nitro compounds 10 by reduction with tin (II) chloride (Scheme 6). Reaction of the amines with acetyl chloride provide the amides 12.

  
• In accordance with Scheme 7 wherein Y is O, and n is an integer from 1-3, an alkyl chain with a carboxylic acid at the terminal end can also be added to the amines 11. For example, reaction with either succinic anhydride (Omuaru, V. O. T.; Indian J. Chem., Sect B. 1998, 37, 814) or β-propiolactone (Bradley, G.; Clark, J.; Kernick, W. J. Chem. Soc., Perkin Trans. 1 1972, 2019) can provide the corresponding carboxylic acids 13. These carboxylic acids are then converted to the hydroxamic acids 14 by treatment with ethyl chloroformate and hydroxylamine (Reddy, A. S.; Kumar, M. S.; Reddy, G. R. Tetrahedron Lett. 2000, 41, 6285).

  
• The amines 11 can also be treated with glycolic acid to afford alcohols 15 (Jursic, B. S.; Zdravkovski, Z. Synthetic Comm. 1993, 23, 2761) as shown in Scheme 8.

  
• As shown in Scheme 9, the aminoindenopyridines 11 may also be treated with chloroacetylchloride followed by amines to provide the more elaborate amines 16 (Weissman, S. A.; Lewis, S.; Askin, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 1998, 39, 7459). Where R₆ is a hydroxyethyl group, the compounds can be further converted to piperazinones 17.

  
• The 4-aminoindenopyridines 19 can be synthesized from the 4-chloroindenopyridines 18 using a known procedure (Gorlitzer, K.; Herbig, S.; Walter, R. D. Pharmazie 1997, 504) or via palladium catalyzed coupling (Scheme 10).

  
• Cyanoesters 20 can be prepared by known methods (Lee, J.; Gauthier, D.; Rivero, R. A. J. Org. Chem. 1999, 64, 3060). Reaction of 20 with enaminone 21 (Iida, H.; Yuasa, Y.; Kibayashi, C. J. Org. Chem. 1979, 44, 1074) in refluxing 1-propanol and triethylamine gave dihydropyridine 22, wherein R is R₅ or R₆ as described above, (Youssif, S.; El-Bahaie, S.; Nabih, E. J. Chem. Res. (S) 1999, 112 and Bhuyan, P.; Borush, R. C.; Sandhu, J. S. J. Org. Chem. 1990, 55, 568), which can then be oxidized and subsequently deprotected to give pyridine 23.

  

  
  II. Specific Compound Syntheses
• Specific compounds which are representative of this invention can be prepared as per the following examples. No attempt has been made to optimize the yields obtained in these reactions. Based on the following, however, one skilled in the art would know how to increase yields through routine variations in reaction times, temperatures, solvents and/or reagents.
• The products of certain syntheses can be used as intermediates to produce more than one of the instant compounds. In those cases, the choice of intermediates to be used to produce compounds of the present invention is a matter of discretion that is well within the capabilities of those skilled in the art.
EXAMPLE 1 Hantzsch Condensation to Form Dihydropyridine 4 (R₁=COOMe; R₂=3,5-dimethylphenyl; R_3b,c=Cl; R_3a,b=H; R₄=Me)
• To a refluxing solution of benzylidene 2 (0.500 g, 1.5 mmol) in acetic acid (10 mL) was added methyl-3-aminocrotonate (0.695 g, 6.0 mmol). The reaction was heated to reflux for 20 minutes, then water was added until a precipitate started to form. The reaction was cooled to room temperature. The mixture was filtered and washed with water to obtain 0.354 g (55%) of a red solid. MS m/z 450 (M⁺+23), 428 (M⁺+1).
EXAMPLE 2 Alternate Hantzsch Conditions to Form Dihydropyridine 4 (R₁=CO₂Me; R₂=2,4-dimethylphenyl; R₃=H; R₄=Et)
• To a refluxing solution of benzylidene 2 (1.00 g, 3.82 mmol) in acetic acid (12 Ml) was added methyl propionylacetate (1.98 g, 15.2 mmol) and ammonium acetate (1.17 g, 15.2 mmol). The reaction was heated for 20 min and then cooled to room temperature. No product precipitated from the solution, so the reaction was heated to reflux and then water was added until a solid began to precipitate. After cooling to room temperature, the mixture was filtered and the red solid washed with water to yield 1.29 g (90%) of product. MS m/z 396 (M⁺+23), 374 (M⁺+1).
EXAMPLE 3 Oxidation of Dihydropyridine 4 to Pyridine 1 (R₁=COOMe; R₂=3,5-dimethylphenyl; R_3b,c=Cl; R_3a,d =H; R ₄=Me)
• To a refluxing solution of dihydropyridine 4 (0.250 g, 0.58 mmol) in acetic acid (10 mL) was added a solution of chromium (VI) oxide (0.584 g, 0.58 mmol) in 1 mL water. After 30 minutes at reflux, the reaction was diluted with water until a precipitate started to form. The mixture was cooled to room temperature and allowed to stand overnight. The mixture was filtered and washed with water to give 0.199 g (81%) of a yellow solid. MS m/z 448 (M⁺+23), 426 (M⁺+1).
EXAMPLE 4 Oxidation of Dihydropyridine 4 to Pyridine 1 (R₁=COOMe; R₂=(4-methyl)-1-naphthyl; R_3b,c=H, NO₂/NO₂, H; R=Me)
• To a refluxing suspension of regioisomeric dihydropyridines 4 (3.59 g, 8.16 mmol) in acetic acid (40 mL) was added a solution of chromium (VI) oxide (0.816 g, 8.16 mmol) in 3 mL water. After 20 minutes at reflux, the reaction was diluted with water until a precipitate started to form. The mixture was cooled to room temperature and allowed to stand overnight. The mixture was filtered and washed with water to yield the mixture of regioisomers as a yellow solid. The products were purified by column chromatography eluting with hexanes:ethyl acetate to yield 1.303 g (37%) of pyridine 1 (R_3b=NO₂; R_3c=H) and 0.765 g (21%) of its regioisomer (R_3b=H: R_3c=NO₂). MS m/z 461 (M⁺+23), 439 (M⁺+1).
EXAMPLE 5 Alternate Three Component Hantzsch Reaction to Form Dihydropyridine 4 (R₁=CO₂Me; R₂=cyclohexyl; R₃=H; R₄=Me)
• Cyclohexane carboxaldehyde (2.0 g, 17.8 mmol), 1,3-indandione (2.6 g, 17.8 mmol), methylacetoacetate (2.0 g, 17.8 mmol), and ammonium hydroxide (1 mL) were refluxed in 8 mL of methanol for 1.5 hours. The temperature was lowered to approximately 50° C. and the reaction was stirred overnight. The reaction was cooled to room temperature, filtered and the solid washed with water. The residue was then dissolved in hot ethanol and filtered while hot. The filtrate was concentrated to yield 4.1 g (68%) of the product which was used without purification. MS m/z 336 (M⁻−1).
EXAMPLE 6 DDQ Oxidation of Dihydropyridine 4 (R₁=CO₂Me; R₂=cyclohexyl; R₃=H; R₄=Me)
• To a solution of dihydropyridine 4 (2.50 g, 7.40 mmol) in 15 mL of dichloromethane was added 2,3-dichloro-3,6-dicyano-1,4-benzoquinone (1.70 g, 7.40 mmol). The reaction was stirred at room temperature for four hours. The mixture was filtered and the residue was washed with dichloromethane. After the filtrate was concentrated, the residue was purified by column chromatography eluting with ethyl acetate: hexanes to yield 0.565 g (23%) of a yellow solid. MS m/z 358 (M⁺+23), 336 (M⁺+1).
EXAMPLE 7 MnO₂ Oxidation of Dihydropyridine 4 (R₁=CO₂Me; R₂=4-(dimethylamino)phenyl; R₃=H; R₄=Me)
• To a solution of dihydropyridine 4 (0.50 g, 1.3 mmol) in 10 mL of dichloromethane was added manganese dioxide (2.5 g, 28.7 mmol). The reaction was stirred at room temperature overnight before filtering and washing with dichloromethane. The filtrate was concentrated to yield 0.43 g (88%) of orange solid 1. MS m/z 395 (M⁺+23), 373 (M⁺+1).
EXAMPLE 8 Cleavage of Carboxylic Ester 5 (R₂=2,4-dimethylphenyl; R₃=H; R₄=Me)
• To a suspension of ester 5 (2.75 g, 6.94 mmol) in acetone (50 mL) was added aqueous 1 M NaOH (100 mL). After stirring at room temperature for 24 hours, the reaction mixture was diluted with 100 mL of water and washed with dichloromethane (2×100 mL). The aqueous layer was cooled to 0° C. and acidified with concentrated HCl. The mixture was filtered and washed with water to yield 1.84 g (77%) yellow solid 6. MS m/z 366 (M⁺+23), 343 (M⁺+1).
EXAMPLE 9 Preparation of Amide 7 (R₂=2,4-dimethylphenyl; R₃=H; R₄=Me; R₅=H; R₆=Me)
• A solution of carboxylic acid 6 (0.337 g, 0.98 mmol) in thionyl chloride (10 mL) was heated at reflux for 1 hour. The solution was cooled and concentrated in vacuo. The residue was diluted with CCl₄ and concentrated to remove the residual thionyl chloride. The residue was then dissolved in THF (3.5 mL) and added to a 0° C. solution of methylamine (1.47 mL of 2.0 M solution in THF, 2.94 mmol) in 6.5 mL THF. The reaction was warmed to room temperature and stirred overnight. The mixture was poured into water, filtered, washed with water and dried to yield 0.263 g (75%) of tan solid. MS m/z 357 (M⁺+1).
EXAMPLE 10 Preparation of Pyridine 1 (R₁=CO₂Et; R₂=4-nitrophenyl; R₃=H; R₄=NH₂)
• To a refluxing solution of benzylidene 2 (1.05 g, 3.76 mmol) in 10 mL of acetic acid was added ethyl amidinoacetate acetic acid salt (0.720 g, 3.76 mmol). The resulting solution was heated at reflux overnight. After cooling to room temperature, the resulting precipitate was removed by filtration and washed with water. This impure residue was heated in a minimal amount of ethanol and then filtered to yield 0.527 g (35%) of a yellow solid. MS m/z 412 (M⁺+23), 390 (M⁺+1).
EXAMPLE 11 Hantzsch Condensation of Benzylidene 8 (R₂=3-methylphenyl) and 1,3-indandione)
• The benzylidene 8 (2.00 g, 9.2 mmol), 1,3-indandione (1.34 g, 0.2 mmmol) and ammonium acetate (2.83 g, 36.7 mmol) were added to 30 mL of ethanol and heated to reflux overnight. The reaction mixture was cooled to room temperature and diluted with ethanol. A yellow precipitate was collected by filtration, washed with ethanol, and dried under vacuum to yield 1.98 g (63%) of the dihydropyridine 9. MS m/z 346 (M⁺+1).
EXAMPLE 12 Reduction to Prepare Amine 11 (R₁=CO₂Me; R₂=4-methylnaphthyl; R₄=Me)
• To a refluxing suspension of pyridine 10 (0.862 g, 1.97 mmol) in 35 mL of ethanol was added a solution of tin (II) chloride dihydrate (1.33 g, 5.90 mmol) in 6 mL of 1:1 ethanol: concentrated HCl. The resulting solution was heated at reflux overnight. Water was added until a precipitate started to form and the reaction was cooled to room temperature. The mixture was then filtered and washed with water. After drying, the residue was purified by column chromatography eluting with hexanes: ethyl acetate to yield 0.551 g (69%) of an orange solid. MS m/z 431 (M⁺+23), 409 (M⁺+1).
EXAMPLE 13 Acetylation of Amine 11 (R₁=CO₂Et; R₂=3,4-methylenedioxyphenyl; R₄=Me)
• To a solution of amine 11 (0.070 g, 0.174 mmol) in 15 mL of dichloromethane was added triethylamine (0.026 g, 0.261 mmol) and acetyl chloride (0.015 g, 0.192 mmol). After stirring overnight at room temperature, the reaction mixture was diluted with water and then extracted with dichloromethane (3×35 mL). The combined organics were washed with brine, dried over MgSO₄, and concentrated. The residue was purified by silica gel chromatography eluting with hexanes: ethyl acetate to yield 0.054 g (70%) of amide 12. MS m/z 467 (M⁺+23), 445 (M⁺+1).
EXAMPLE 14 Preparation of Carboxylic Acid 13 (R₁=CO₂Me; R₂=3,5-dimethylphenyl; R₄=Me; Y=O; n=2).
• To a suspension of amine 11 (0.079 g, 0.212 mmol) in 5 mL of benzene was added succinic anhydride (0.021 g, 0.212 mmol). After heating at reflux for 24 hours, the reaction mixture was filtered and washed with benzene. The residue was dried under high vacuum and then washed with ether to remove the excess succinic anhydride. This yielded 0.063 g (63%) of carboxylic acid 13. MS m/z 473 (M⁺+1).
EXAMPLE 15 Preparation of Carboxylic Acid 13 (R₁=CO₂Me; R₂=3,5-dimethylphenyl; R₄=Me; Y=H₂; n=1)
• To a refluxing solution of amine 11 (0.078 g, 0.210 mmol) in 5 mL of acetonitrile was added β-propiolactone (0.015 g, 0.210 mmol). The reaction was heated to reflux for 72 hours before cooling to room temperature. The reaction mixture was concentrated. The residue was mixed with 10% aqueous sodium hydroxide and washed sequentially with ether and ethyl acetate. The aqueous layer was acidified with concentrated HCl and extracted with dichloromethane (2×25 mL). The combined organics were dried over MgSO₄, filtered, and concentrated. The residue was purified by column chromatography eluting with 5% MeOH in dichloromethane to yield 0.020 g (21%) of an orange solid. MS m/z 467 (M⁺+23), 445 (M⁺+1).
EXAMPLE 16 Preparation of Hydroxamic Acid 14 (R₁=CO₂Me; R₂=(4-methyl)-1-naphthyl; Y=O; n=2; R₄=Me)
• To a 0° C. suspension of carboxylic acid 13 (0.054 g, 0.106 mmol) in 10 mL of diethyl ether was added triethylamine (0.014 g, 0.138 mmol) and then ethyl chloroformate (0.014 g, 0.127 mmol). The mixture was stirred at 0° C. for 30 minutes and them warmed to room temperature. A solution of hydroxylamine (0.159 mmol) in methanol was added and the reaction was stirred overnight at room temperature. The mixture was filtered and the residue was washed with ether and dried under vacuum to yield 0.030 g (54%) of a yellow solid. MS m/z 524 (M⁺+1).
EXAMPLE 17 Preparation of Amide 15 (R₁=CO₂Me; R₂=3,5-dimethylphenyl; R₄=Me)
• A mixture of amine 11 (0.201 g, 0.54 mmol) and glycolic acid (0.049 g, 0.65 mmol) was heated at 120-160° C. for 30 minutes. During heating, more glycolic acid was added to ensure that excess reagent was present. Once the starting material was consumed, the reaction was cooled to room temperature, and diluted with dichloromethane. The resulting mixture was extracted with 20% NaOH, followed by 10% HCl, and finally water. The combined organics were concentrated and triturated with ether. Purification by column chromatography eluting with ethyl acetate: hexanes yielded 0.012 g (5%) of a yellow solid. MS m/z 453 (M⁺+23), 431 (M⁺+1).
EXAMPLE 18 Preparation of Amide 16 (R₁=CO₂Me; R₂=3,5-dimethylphenyl; R₄=Me; NR₆R₇=morpholino)
• To a 0° C. mixture of amine 11 (0.123 g, 0.331 mmol) in 2 mL of 20% aqueous NaHCO₃ and 3 mL of ethyl acetate was added chloroacetyl chloride (0.047 g, 0.413 mmol). The reaction was warmed to room temperature and stirred for 45 minutes. The mixture was poured into a separatory funnel and the aqueous layer was removed. The organic layer containing the crude chloroamide was used without purification. To the ethyl acetate solution was added morpholine (0.086 g, 0.992 mmol) and the reaction was heated to approx. 65° C. overnight. The reaction was diluted with water and cooled to room temperature. After extraction with ethyl acetate (3×25 mL), the combined organics were washed with brine, dried over MgSO₄ and concentrated to yield 0.130 g (79%) of a yellow solid. MS m/z 522 (M⁺+23), 500 (M⁺+1).
EXAMPLE 19 Preparation of piperazinone 17 (R₁=CO₂Me; R₂=3,5-dimethylphenyl; R₄=Me; R₇=H)
• To a 0° C. solution of amide 16 (R₆=CH₂CH₂OH) (0.093 g, 0.20 mmol), tri n-butylphosphine (0.055 g, 0.27 mmol) in 0.35 mL ethyl acetate was slowly added di-tert-butyl azodicarboxylate (0.062 g, 0.27 mmol) in 0.20 mL ethyl acetate. The reaction was allowed to stand for 15 minutes and then heated to 40° C. overnight. 4.2 M ethanolic HCl was added dropwise. The mixture was cooled to 0° C. and allowed to stand for 2 hours. The mixture was filtered and washed with cold ethyl acetate. Purification by column chromatography with 1-5% MeOH in CH₂Cl₂ yielded 0.011 (12%) of a white solid. MS m/z 478 (M⁺+23), 456 (M⁺+1).
EXAMPLE 20 Preparation of 4-Aminoindenopyridine 19 (R₁=CO₂Me; R₄=Me; R₆=Me; R₇=phenyl)
• To a solution of 4-chloroindenopyridine 18 (0.069 g, 0.240 mmol) in 10 mL of 2-ethoxyethanol was added N-methylaniline (0.026 g, 0.240 mmol). The reaction was heated at reflux for 96 hours. After cooling to room temperature, the solution was concentrated. The residue was purified by column chromatography eluting with hexanes: ethyl acetate to yield 0.029 g (34%) of an orange solid. MS m/z 359 (M⁺+1).
EXAMPLE 21 Preparation of 4-Aminoindenopyridine 19 (R₁=CO₂Me; R₄=Me; R₆=H; R₇=cyclopentyl) by Palladium Catalyzed Coupling
• A mixture of 4-chloroindenopyridine 18 (0.100 g, 0.347 mmol), cyclopentylamine (0.035 g, 0.416 mmol), palladium (II) acetate (0.004 g, 0.0017 mmol), 2-(di-t-butylphosphino)biphenyl (0.010 g, 0.0035 mmol), and cesium carbonate (0.124 g, 0.382 mmol) in 10 mL of dioxane was heated at reflux overnight. The reaction was cooled to room temperature, diluted with water, and extracted with ethyl acetate (3×35 mL). The combined organics were washed with brine, dried over Na₂SO₄, and concentrated. The residue was purified by column chromatography eluting with ethyl acetate: hexanes. The purified oil was dissolved in ether and cooled to 0° C. To this solution was slowly added 1.0 M HCl in ether. The resulting precipitate was isolated by filtration, washed with ether, and dried under vacuum to yield 0.032 g (25%) of a yellow solid. MS m/z 359 (M⁺+23), 337 (M⁺+1).
EXAMPLE 22 Preparation of Dihydropyridine 21 (R₁=CO₂Me; R₂=2-furyl; R₃=H; R₄=NH₂)
• Unsaturated cyanoester 20 (0.20 g, 1.10 mmol), enamine 21 (0.20 g, 0.75 mmol) and 5 drops of triethylamine were refluxed in 1-propanol (4 mL). After 3 hours, the reaction was concentrated to half the volume and cooled. The resulting precipitate was filtered and washed with 1-propanol. The precipitate was a mixture of products and therefore was combined with the filtrate and concentrated. Purification by column chromatography, eluting with ethyl acetate: hexane yielded 0.11 g (34%) of the red product 22. MS m/z 465 (M⁺+23).
EXAMPLE 23 DDQ Oxidation/Deprotection of Dihydropyridine 22 (R₁=CO₂Me; R₂=3-furyl; R₃=H; R₄=NH₂)
• To a solution of dihydropyridine 22(0.05 g, 0.11 mmol) in chlorobenzene (4 mL) was added 2,3-dichloro-3,6-dicyano-1,4-benzoquinone (0.05 g, 0.22 mmol). The reaction was refluxed overnight before cooling to room temperature and diluting with diethyl ether. The reaction mixture was filtered through celite and concentrated in vacuo. Purification by column chromatography, eluting with ethyl acetate:hexane yielded 0.018 g (52%) of yellow product 23. MS m/z 343 (M⁺+23), 321 (M⁺+1).
• Following the general synthetic procedures outlined above and in Examples 1-21, the compounds of Table 1 below were prepared.

  TABLE 1

  No.	R1	R2	R3a	R3b	R3c	R3d	R4	MS (M + 1)

  1	CN	C7H5O2	H	H	H	H	Me	341
  2	CO2Et	C7H5O2	H	H	H	H	Me	388
  3	CO2t-Bu	C7H5O2	H	H	H	H	Me	416
  4	CO2t-Bu	C8H9O2	H	H	H	H	Me	432
  5	CO2Et	C6H4NO2	H	H	H	Me	389
  6	CO2H	C7H5O2	H	H	H	H	Me	360
  7	CO2Et	C14H13O2	H	H	H	H	Me	480
  8	CO2Et	C8H8BrO2	H	H	H	H	Me	482
  9	CO2Et	C11H9O	H	H	H	H	Me	424
  10	CO2H	C8H9	H	H	H	H	Me	376
  11	CO2Et	Ph	H	H	H	H	Me	344
  12	CO2Et	C7H7O	H	H	H	H	Me	374
  13	CO2Et	C9H11O3	H	H	H	H	Me	434
  14	CO2Et	C6H4BrO2	H	H	H	H	Me	454
  15	CO2Bn	C7H5O2	H	H	H	H	Me	450
  16	C11H14NO2	C7H5O2	H	H	H	H	Me	507
  17	CO2Me	C8H9O2	H	H	H	H	Me	390
  18	CO2Me	C7H5O2	H	H	H	H	Me	374
  19	CO2Et	C8H9O2	H	H	H	H	Me	404
  20	CO2Et	C8H9O2	H	H	H	H	Me	404
  21	CO2Et	C7H6BrO	H	H	H	H	Me	454
  22	CO2Et	C7H5O2	H	H	H	H	NH2	411 (M + 23)
  23	CO2Et	C7H5O2	H	H	H	H	Me	388
  25	CO2Et	C8H9O2	H	H	H	H	NH2	405
  26	CO2Et	C6H4NO2	H	H	H	H	NH2	390
  27	CO2Et	Ph	H	H	H	H	NH2	345
  28	CO2Et	C9H11O	H	H	H	H	Me	402
  29	CO2Et	C8H8BrO2	H	H	H	H	Me	483
  30	CO2Me	Ph	H	H	H	H	Me	330
  31	CO2Et	C8H7O2	H	H	H	H	Me	402
  32	CO2Et	C7H5O2	H	NO2	H	H	Me	433
  33	C4H4NO2	C7H5O2	H	H	H	H	Me	413
  34	CO2Et	C7H4NO4	H	H	H	H	Me	433
  35	CO2Et	C7H5O2	H	H	NO2	H	Me	433
  36	CO2Me	C7H4F3	H	H	H	H	Me	398
  37	CO2Et	C7H5O2	H	H	NH2	H	Me	403
  38	CONH2	C7H5O2	H	H	H	H	Me	359
  39	CO2Et	C8H9	H	H	H	H	Me	372
  40	CO2Et	C7H5O2	H	NH2	H	H	Me	403
  41	CO2Et	C4H3O	H	H	H	H	Me	334
  42	CO2Et	2-Thienyl	H	H	H	H	Me	350
  43	CO2Me	C8H9	H	H	H	H	Me	358
  44	CO2Me	C8H7O2	H	H	H	H	Me	388
  45	CO2Me	C7H4NO4	H	H	H	H	Me	419
  46	CO2Me	C9H11O	H	H	H	H	Me	388
  47	CO2Me	4-Pyridyl	H	H	H	H	Me	331
  48	CO2Me	C7H5O2	H	H	H	H	Me	374
  49	CO2Me	C7H4BrO2	H	H	H	H	Me	454
  50	CO2Me	C7H6BrO	H	H	H	H	Me	439
  51	CO2Me	C8H9	H	H	H	H	Me	358
  52	CO2Et	C8H9	H	H	H	H	Me	372
  53	CO2Me	C11H9O	H	H	H	H	Me	410
  54	CO2Me	C6H4NO2	H	H	H	H	Me	375
  55	CO2Et	C7H5O2	H	NHAc	H	H	Me	445
  56	CO2Et	C7H5O2	H	H	NHAc	H	Me	445
  57	CO2Et	C7H7	H	H	H	H	Me	358
  58	CO2Et	C7H7	H	H	H	H	Me	358
  59	CO2Et	C7H7	H	H	H	H	Me	358
  60	CO2Et	C7H4F3	H	NO2	H	H	Me	457
  61	CO2Et	C7H4F3	H	H	NO2	H	Me	457
  62	CO2Me	C7H7	H	H	H	H	Me	344
  63	CO2Et	C7H4F3	H	NH2	H	H	Me	427
  64	CO2Et	C7H4F3	H	H	NH2	H	Me	427
  65	CO2Me	C8H3F6	H	H	H	H	Me	466
  66	CO2Me	C7H7	H	H	H	H	Me	344
  67	CO2Me	C7H7	H	H	H	H	Me	344
  68	CO2Me	C7HF3	H	NO2	H	H	Me	443
  69	CO2Me	C7H4F3	H	H	NO2	H	Me	443
  70	CO2Et	C8H9	H	H	H	H	i-Pr	400
  71	CO2Me	C7H4F3	H	NH2	H	H	Me	413
  72	CO2Me	C6H3Cl2	H	H	H	H	Me	399
  73	CO2Me	C8H9	H	H	H	H	Et	372
  74	CO2Me	C7H4F3	H	H	H	H	Me	398
  75	CO2Me	C11H9	H	H	H	H	Me	394
  76	CO2Me	C9H11	H	H	H	H	Me	372
  77	CO2Me	C8H9	H	NO2	H	H	Me	403
  78	CO2Me	C8H9	H	H	NO2	H	Me	403
  79	CO2Me	C11H9	H	H	H	H	Me	394
  80	CO2Me	C7H4F3	H	NHAc	H	H	Me	455
  81	CO2Me	C6H3Br2	H	H	H	H	Me	488
  82	CO2Me	C8H9	H	NH2	H	H	Me	373
  83	CO2Me	C8H9	H	H	NH2	H	Me	373
  84	CO2Me	C7H6F	H	H	H	H	Me	362
  85	CO2Me	C6H4Br	H	H	H	H	Me	431 (M + 23)
  86	CO2Me	C10H7	H	H	H	H	Me	380 (M +23)
  87	CO2Me	C11H9	H	NO2	H	H	Me	439
  88	CO2Me	C11H9	H	H	NO2	H	Me	439
  89	CO2Me	C14H9	H	H	H	H	Me	430
  90	CO2Me	C11H9	H	NH2	H	H	Me	409
  91	CO2Me	C11H9	H	H	NH2	H	Me	409
  92	C4H4NO2	C8H9	H	H	H	H	Me	397
  93	CN	C8H9	H	H	H	H	Me	325
  94	CO2Me	C8H9	H	H	H	H	NH2	359
  95	CO2Me	C11H9	H	H	H	H	NH2	395
  96	CO2H	C8H9	H	H	H	H	Me	344
  97	C4H4NO2	C11H9	H	H	H	H	Me	433
  98	CN	C11H9	H	H	H	H	Me	361
  99	C2H2 O 2	C7H5O2	H	H	H	H	C2H2O2	358
  100	C2H2O2	C8H10N	H	H	H	H	C2H2O2	357
  101	C2H2O2	Ph	H	H	H	H	C2H2O2	314
  102	C2H2O2	p-C6H4NO2	H	H	H	H	C2H2O2	361
  103	C2H2O2	C8H9	H	H	H	H	C2H2O2	364
  104	C2H2	C8H9	H	H	H	H	C2H2O2	342
  105	CO2H	C11H9	H	H	H	H	Me	380
  106	CONH2	C8H9	H	H	H	H	Me	343
  107	CONHMe	C8H9	H	H	H	H	Me	357
  108	CONMe2	C8H9	H	H	H	H	Me	371
  109	C2H2O2	C11H9	H	H	H	H	C2H2O2	378
  110	C2H2O2	C7H7	H	H	H	H	C2H2O2	328
  111	C2H2O2	C9H11	H	H	H	H	C2H2O2	356
  112	C2H2O2	C7H7	H	H	H	H	C2H2O2	328
  113	CO2Me	C6H4NO2	H	H	H	H	Me	375
  114	C2H2O2	C7H7	H	H	H	H	C2H2O2	328
  115	CO2Me	C8H10N	H	H	H	H	Me	373
  116	CONH2	C11H9	H	H	H	H	Me	379
  117	C2H2O2	C9H6N	H	H	H	H	C2H2O2	365
  118	CO2Me	C6H4NO2	H	H	H	H	Me	375
  119	CONHMe	C11H9	H	H	H	H	Me	393
  120	CONMe2	C131H9	H	H	H	H	Me	407
  121	CO2Me	C9HN	H	H	H	H	Me	381
  122	CO2Me	C11H9	H	Cl	Cl	H	Me	463
  123	CO2Me	C8H9	H	Cl	Cl	H	Me	427
  124	CO2Me	C9H6N	H	H	H	H	Me	381
  125	CO2Et	C11H9	H	H	H	H	Me	408
  126	CO2Me	C6H3Br2	H	Cl	Cl	H	Me	555
  127	CO2Me	C8H9	Cl	H	H	Cl	Me	427
  128	CO2Me	2-NO2-4,5- OCH2O—C6H2	H	H	H	H	Me	421
  129	CO2Me	C6H3Br2	Cl	H	H	Cl	Me	558
  130	CO2Me	C6H6N	H	H	H	H	Me	345
  131	CO2Et	C11H9	H	Cl	Cl	H	Me	477
  132	CO2Me	C6H4Br2N	H	H	H	H	Me	503
  133	Ac	C6H3Br2	H	H	H	H	Me	472
  134	Ac	C8H9	H	H	H	H	Me	342
  135	CO2Me	C5H4N	H	H	H	H	Me	331
  136	C4H4NO2	C6H3Br2	H	H	H	H	Me	527
  137	C4H4NO2	C8H9	H	H	H	H	Me	397
  138	CO2Me	C6H5O2	H	H	H	H	Me	362
  139	CO2H	C6H3Br2	H	H	H	H	Me	474
  140	CO2H	C8H9	H	H	H	H	Me	344
  141	CO2Me	C6H5O	H	H	H	H	Me	346
  142	CO2Me	C10 H2	H	H	H	H Me	380
  143	CO2Me	C16H25O	H	H	H	H	Me	486
  144	CO2Me	C13H11O	H	H	H	H	Me	436
  145	CO2Me	C7H5Br2O	H	H	H	H	Me	518
  146	C4H4NO2	C7H5Br2O	H	H	H	H	Me	557
  147	C4H4NO2	C8H9	H	Cl	Cl	H	Me	466
  148	CO2Et	—NHPh	H	H	H	H	Me	359
  149	CO2Me	C7H7O	H	H	H	H	Me	360
  150	CO2Me	C6H3Br2O	H	H	H	H	Me	504
  151	C4H4NO2	C9H6N	H	H	H	H	Me	420
  152	C3H5O3	C6H3Br2O	H	H	H	H	Me	534
  153	C4H4NO2	C6H5 O	H	H	H	H	Me	385
  154	C2H4NO2	C8H9	H	H	H	H	Me	373
  155	C4H4NO2	C6H3Br2	H	H	NO2	H	Me	574
  156	CO2Me	C11H9	H	Br	H	H	Me	473
  157	CO2Me	C11H9	H	H	Br	H	Me	473
  158	C4H4NO2	C9H6N	H	Cl	Cl	H	Me	489
  159	C4H4NO2	C6H3Br2O	H	H	NO2	H	Me	590
  160	C3H5O3	C9H6N	H	H	H	H	Me	411
  161	CO2Me	C8H9	H	Br	H	H	Me	436
  162	CO2Me	C8H9	H	H	Br	H	Me	438
  163	CO2Me	C8H9	H	Br	Br	H	Me	516
  164	C4H4NO2	C6H32Br2	H	Cl	Cl	H	Me	597
  165	C3H5O3	C9H6N	H	Cl	Cl	H	Me	480
  166	CO2Me	C11H9	H	Br	Br	H	Me	552
  167	CO2Et	C8H9	H	Br	Br	H	Me	530
  168	CO2Me	C6H3Br2O	F	H	H	F	Me	540
  169	CO2Me	C6H3Br2O	H	H	NO2	H	Me	551
  170	CO2Me	C6H3Br2O	H	Cl	Cl	H	Me	573
  171	C4H4NO2	C8H9	H	H	NO2	H Me	444
  172	C4H4NO2	C8H9	H	NO2	H	H	Me	444
  173	CO2Me	C8H9	F	H	H	F	Me	394
  174	C4H4NO2	C8H9	F	H	H	F	Me	433
  175	CO2Me	C8H9O2	H	Br	Br	H	Me	548
  176	CO2Me	C7H4N	H	H	H	H	Me	355
  177	CO2Me	C8H9O	H	NO2	H	H	Me	421
  178	CO2Me	C8H9O	H	H	NO2	H	Me	453
  179	CO2Me	C8H9O	H	Cl	Cl	H	Me	443
  180	CN	C8H9O	H	H	H	H	Me	341
  181	CO2Me	C6H3I2O	H	H	H	H	Me	598
  182	CO2Me	C6H3F2	H	Cl	Cl	H	Me	435
  183	CO2Et	C8H10N	H	H	H	H	Me	387
  184	CO2Et	C7H8N	H	H	H	H	Me	373
  185	CO2Me	C7H5I2O	H	H	H	H	Me	612
  186	CO2Et	C9H7N2	H	H	H	H	Me	410
  187	CO2Me	C6H3I2O	H	H	NO2	H	Me	345
  188	CO2Me	C6H3I2O	H	Cl	Cl	H	Me	668
  189	CO2Me	C6H3F2	H	H	NO2	H	Me	413
  190	CO2H	C6H3Br2	H	Cl	Cl	H	Me	544
  191	CN	C6H3I2O	H	H	H	H	Me	565
  192	CO2Me	C6H3Br2O	H	Br	H	H	Me	606 (M + 23)
  193	CO2Me	C6H3Br2O	H	H	Br	H	Me	584
  194	CO2Et	C7H8N	H	H	H	H	Me	373
  195	CO2Et	C6H4Cl2N	H	H	H	H	Me	427
  196	CO2Et	C6H3Br2O	H	Cl	Cl	H	Me	587
  197	CO2Et	C6H5BrN	H	H	H	H	Me	437
  198	CO2Et	C7H8NO	H	H	H	H	Me	389
  199	CO2Et	C6H3I2O	H	H	H	H	Me	612
  200	CO2Et	C6H3F2	H	Cl	Cl	H	Me	449
  201	CO2Me	C9H6N	H	Cl	Cl	H	Me	450
  202	CO2Me	C7H5F2O	H	Cl	Cl	H	Me	465
  203	CO2Me	C7H5F2O	H	H	H	H	Me	396
  204	CO2Me	C8H9	H	C4H6NO3	H	H	Me	473
  205	CO2Me	C6H6N	H	H	H	H	Me	345
  206	CO2Me	C7H8N	H	H	H	H	Me	359
  207	CO2Me	C6H4NO2	H	Cl	Cl	H	Me	444
  208	CO2Me	C7H4N	H	H	H	Me	355
  209	CO2H	C10H7	H	H	H	H	Me	366
  210	CO2Me	C6H4NO2	H	Cl	Cl	H	Me	444
  211	CO2Me	C7H6F	H	Cl	Cl	H	Me	430
  212	CO2Me	C7H3F4	H	H	H	H	Me	416
  213	CO2Me	C7H6F	H	Cl	Cl	H	Me	430
  214	CO2Me	C6H4Cl2N	H	H	H	H	Me	413
  215	CO2Me	C8H9	H	OMe	OMe	H	Me	418
  216	CO2Me	C11H9	H	OMe	OMe	H	Me	454
  217	CO2Me	C7H6F	H	H	H	H	Me	362
  218	CO2Me	C8H9	H	C3H6NO2	H	H	Me	445
  219	CO2Me		H	H	H	H	Me	359
  220	CO2Me	—NHPh	H	H	H	H	Me	345
  221	CO2Me	C6H5BrN	H	H	H	H	Me	423
  222	CO2Me	2-Pyridyl	H	H	H	H	Me	353
  223	CO2Me	C6H3Cl2	H	OMe	OMe	H	Me	459
  224	CO2Me	C7H3F4	H	Cl	Cl	H	Me	485
  225	CO2Me	C6H6N	H	H	H	H	Me	345
  226	CO2Me	C6H4NO2	H	H	NO2	H	Me	420
  227	CO2Me	C6N4NO2	H	H	NO2	H	Me	420
  228	CO2Me	C7H8N	H	H	H	H	Me	359
  229	CO2Me	C9H7N2	H	H	H	H	Me	396
  230	CO2Me	C121H9	H	OH	OH	H	Me	426
  231	CO2Me	C8H9	H	H	F	H	Me	376
  232	CO2Me	C7H3F4	H	H	NO2	H	Me	461
  233	CO2Me	C10H6F	H	Cl	Cl	H	Me	468
  234	CO2Me	C8H10N	H	H	H	H	Me	373
  235	CO2Me	C7H8NO	H	H	H	H	Me	375
  236	CO2Me	C10H6F	H	NO2	H	H	Me	443
  237	CO2Me	C10H6F	H	H	NO2	H	Me	443
  238	CO2Me	C10 H6F	H	H	H	H	Me	398
  239	CO2Me	C12H12N	H	Cl	Cl	H	Me	491
  240	CO2Me	C11H9	H	C4H6NO3	H	H	Me	509
  241	CO2Me	C8H9	H	H	C4H6NO3	H	Me	473
  242	CO2Me	C11H9	H	H	C4H6NO3	H	Me	509
  243	CO2Me	C4H9	H	H	H	H	Me	310
  244	CO2Me	C11H9	H	C4H7N2O3	H	H	Me	524
  245	CO2Me	C8H9	H	H	C4H7N2O3	H	Me	488
  246	CO2Me	C4H7	H	H	H	H	Me	308
  247	CO2Me	i-Pr	H	H	H	H	Me	296
  248	CO2Me	Cyclohexyl	H	H	H	H	Me	336
  249	CO2Me	Me	H	H	H	H	Me	268
  250	CO2Me	C8H9	H	H	C4H9N2O2	H	Me	474
  251	CO2Me	C7H9	H	H	C5H8NO3	H	Me	487
  252	CO2Me	N-Mopholino	H	H	H	H	Me	339
  253	CO2Me	C5H10 N	H	H	H	H	Me	337
  254	CO2Me	C8H9	H	H	C5H11N2O2	H	Me	488
  255	CO2Me	C8H9	H	C4H9N2O2	H	H	Me	474
  256	CO2Me	C8H9	H	C4H7N2O	H	H	Me	456
  257	CO2Me	C8H9	H	C2H4NO2	H	H	Me	431
  258	CO2Me	C8H9	H	C6H11N2O2	H	H	Me	500
  259	CO2Me	C8H9	H	C6H12N3O	H	H	Me	499
  260	CO2Me	C8H9	H	C5H6N3O	H	H	Me	481
  261	CO2Me	C8H9	H	H	C6H11N2O2	H	Me	500
  262	CO2Me	C8H9	H	H	C6H12N3O	H	Me	499
  263	CO2Me	C8H9	H	H	C2H4NO2	H	Me	431
  264	CO2Me	C7H5O2	H	H	H	H	NH2	397 (M + 23)
  265	CO2Me	Ph	H	H	H	H	NH2	353 (M + 23)
  266	CO2Me	C8H9O2	H	H	H	H	NH2	413 (M + 23)
  267	CO2Me	2-Furyl	H	H	H	H	NH2	321
  268	CO2Me	3-Furyl	H	H	H	H	NH2	321
  269	CO2Me	2-Furyl	H	H	H	H	Me	320
  270	CO2Me	2-Furyl	H	H	H	NH2	Me	335
  271	CO2Me	2-Furyl	NHOH	H	H	H	Me	351
  272	CO2Et	2-Furyl	H	H	H	H	NH2	335
  273	CO2Et	2-Furyl	H	Br	H	H	NH2	413
  274	CO2Et	2-Furyl	H	H	Br	H	NH2	413
  275	CO2Et	C7H4BrO 2	H	H	H	H	Me	467
  276	CO2Me	C8H9	H	H	C5H6N3O	H	Me	481
  277	CO2Me	C8H9	H	H	C4H7N2O	H	Me	456
  278	CO2Me	C8H9	H	C4H6NO3	H	H	Me	473
  279	CO2Me	C8H9	H		H	H	Me	513
  280	CO2Me	C8H9	H		H	H	Me	516
  281	CO2Me	C8H9	H		H	H	Me	501
  282	CO2Me	C8H9	H		H	H	Me	566
  283	CO2Me	C8H9	H		H	H	Me	488
  284	CO2Me	C8H9	H	H		H	Me	541

  
  III. Biological Assays and Activity
  Ligand Binding Assay for Adenosine A2a Receptor
• Ligand binding assay of adenosine A2a receptor was performed using plasma membrane of HEK293 cells containing human A2a adenosine receptor (Perkin Elmer, RB-HA2a) and radioligand [³H]CGS21680 (PerkinElmer, NET1021). Assay was set up in 96-well polypropylene plate in total volume of 200 mL by sequentially adding 20 mL 1:20 diluted membrane, 130 mLassay buffer (50 mM Tris.HCl, pH7.4 10 mM MgCl₂, 1 mM EDTA) containing [³H] CGS21680, 50 mL diluted compound (4×) or vehicle control in assay buffer. Nonspecific binding was determined by 80 mM NECA. Reaction was carried out at room temperature for 2 hours beofre filtering through 96-well GF/C filter plate pre-soaked in 50 mM Tris.HCl, pH7.4 containing 0.3% polyethylenimine. Plates were then washed 5 times with cold 50 mM Tris.HCl, pH7.4., dried and sealed at the bottom. Microscintillation fluid 30 ml was added to each well and the top sealed. Plates were counted on Packard Topcount for [³H]. Data was analyzed in Microsoft Excel and GraphPad Prism programs. (Varani, K.; Gessi, S.; Dalpiaz, A.; Borea, P. A. British Journal of Pharmacology, 1996, 117, 1693)
• Adenosine A2a Receptor Functional Assay
• CHO-K1 cells overexpressing human adenosine A2a receptors and containing cAMP-inducible beta-galactosidase reporter gene were seeded at 40-50K/well into 96-well tissue culture plates and cultured for two days. On assay day, cells were washed once with 200 mL assay medium (F-12 nutrient mixture/0.1% BSA). For agonist assay, adenosine A2a receptor agonist NECA was subsequently added and cell incubated at 37 C, 5% CO₂ for 5 hrs before stopping reaction. In the case of antagonist assay, cells were incubated with antagonists for 5 minutes at R.T. followed by additon of 50 nM NECA. Cells were then incubated at 37 C, 5% CO₂ for 5 hrs before stopping experiments by washing cells with PBS twice. 50 mL 1× lysis buffer (Promega, 5× stock solution, needs to be diluted to 1× before use) was added to each well and plates frozen at −20 C. For b-galactosidase enzyme colormetric assay, plates were thawed out at room temperature and 50 mL 2× assay buffer (Promega) added to each well. Color was allowed to develop at 37 C for 1 hr. or until reasonable signal appeared. Reaction was then stopped with 150 mL 1 M sodium carbonate. Plates were counted at 405 nm on Vmax Machine (Molecular Devices). Data was analyzed in Microsoft Excel and GraphPad Prism programs. (Chen, W. B.; Shields, T. S.; Cone, R. D. Analytical Biochemistry, 1995, 226, 349; Stiles, G. Journal of Biological Chemistry, 1992, 267, 6451)
• Assay of Phosphodiesterase Activity
• The assay of phosphodiesterase activity follows the homogeneous SPA (scintillation proximity assay) format under the principle that linear nucleotides preferentially bind yttrium silicate beads in the presence of zinc sulfate.
• In this assay, the enzyme converts radioactively tagged cyclic nucleotides (reaction substrate) to linear nucleotides (reaction product) which are selectively captured via ion chelation on a scintillant-containing bead. Radiolabeled product bound to the bead surface results in energy transfer to the bead scintillant and generation of a quantifiable signal. Unbound radiolabel fails to achieve close proximity to the scintillant and therefore does not generate any signal.
• Specifically, enzyme was diluted in PDE buffer (50 mM pH 7.4 Tris, 8.3 mM MgCl₂, 1.7 mM EGTA) with 0.1% ovalbumin such that the final signal:noise (enzyme:no enzyme) ratio is 5-10. Substrate (2,8- ³H-cAMP or 8-³H-cGMP, purchased from Amersham Pharmacia) was diluted in PDE (4, 5, 7A) buffer to 1 nCi per μl (or 1 μCi/ml). For each test well, 48 μl of enzyme was mixed with 47 μl substrate and 5 μl test compound (or DMSO) in a white Packard plate, followed by shaking to mix and incubation for 15 minutes at room temperature. A 50 μl aliquot of evenly suspended yttrium silicate SPA beads in zinc sulfate was added to each well to terminate the reaction and capture the product. The plate was sealed using Topseal-S (Packard) sheets, and the beads were allowed to settle by gravity for 15-20 minutes prior to counting on a Packard TopCount scintillation counter using a ³H glass program with color quench correction. Output was in color quench-corrected dpm.
• Test compounds were diluted in 100% DMSO to a concentration 20× final assay concentration. DMSO vehicle alone was added to uninhibited control wells. Inhibition (%) was calculated as follows:
  Nonspecific binding (NSB)=the mean of CPM of the substrate+buffer+DMSO wells
  Total Binding (TB)=the mean of the enzyme+substrate+DMSO wells
  % Inhibition listed in Table 1=(1−(Sample CPM−NSB))×100
• The IC₅₀ values were calculated using the Deltagraph 4-parameter curve-fitting program. The IC₅₀ and % Inhibition data on PDE 4, 5, and 7A are listed for the indicated compounds in Table 2 below.

  TABLE 2

  MS

  IC50 (μM)/% inh. @ μM

  No.	R1	R2	R3a	R3b	R3c	R3d	R4	(M + 1)	PDE7A	PDE4	PDE5

  6	CO2H	C7H5O2	H	H	H	H	Me	360	45% @20	49% @ 5
  51	CO2Me	C8H9	H	H	H	H	Me	358	0.055	0.353	2.7
  56	CO2Et	C7H5O2	H	H	NHAc	H	Me	445	0.074	0.333	2.5
  70	CO2Et	C8H9	H	H	H	H	i-Pr	400	2.11
  73	CO2Me	C9H9	H	H	H	H	Et	372	1.54		0.998
  82	CO2Me	C8H9	H	NH2	H	H	Me	373	0.021	0.204	1.11, 0.864
  90	CO2Me	C11H9	H	NH2	H	H	Me	409	0.005	0.237, 0.172	2.33
  98	CN	C11H9	H	H	H	H	Me	361	1.13
  119	CONHMe	C11H9	H	H	H	H	Me	393	0.658		41% @20
  133	Ac	C6H3Br2	H	H	H	H	Me	472	1.54
  134	Ac	C8H9	H	H	H	H	Me	342	1.14
  169	CO2Me	C6H3Br2O	H	H	NO2	H	Me	551	0.0053		0.184
  170	CO2Me	C6H3Br2O	H	Cl	Cl	H	Me	573	0.0087		0.557
  190	CO2H	C6H3Br2	H	Cl	Cl	H	Me	544	5.9
  191	CN	C6H3I2O	H	H	H	H	Me	565	0.593
  197	CO2Et	C6H5BrN	H	H	H	H	Me	437	0.728	69% @ 5	0.362
  219	CO2Me	C7H8N	H	H	H	H	Me	359	0.964	61% @ 5	1.1
  220	CO2Me	—NHPh	H	H	H	H	Me	345	0.084	1.8	0.637
  241	CO2Me	C8H9	H	H	C4H6NO3	H	Me	473	0.0035	0.954	0.183
  242	CO2Me	C11H9	H	H	C4H6NO3	H	Me	509	0.0038	0.782	0.141
  243	CO2Me	C4H9	H	H	H	H	Me	310	2.6
  245	CO2Me	C8H9	H	H	C4H7N2O3	H	Me	488	0.0053	0.875	0.185
  248	CO2Me	Cyclohexyl	H	H	H	H	Me	336	0.783	0.171	0.649
  250	CO2Me	C8H9	H	H	C4H9N2O2	H	Me	474	0.0074	0.684	2.4
  251	CO2Me	C8H9	H	H	C5H8NO3	H	Me	487	0.0054	0.754	0.26
  253	CO2Me	C5H10N	H	H	H	H	Me	337	0.905	0.85	0.303
  254	CO2Me	C8H9	H	H	C5H11N2O2	H	Me	488	0.0067	0.664	0.765
  261	CO2Me	C8H9	H	H	C6H11N2O2	H	Me	500	0.0063	0.477	0.63
  262	CO2Me	C8H9	H	H	C6H12N3O	H	Me	499	0.008	0.702	3.7

• TABLE 3

  Ki (nM)

  										A2a
  									A2a	an-	A1
  								MS	bind-	tagonist	bind-
  No.	R1	R2	R3a	R3b	R3c	R3d	R4	(M + 1)	ing	function	ing

  14	CO2Et	C6H4BrO2	H	H	H	H	Me	454	451
  22	CO2Et	C7H5O2	H	H	H	H	NH2	411 (M +23)	70	253
  18	CO2Me	C7H5O2	H	H	H	H	Me	374	159	>1000	584
  27	CO2Et	Ph	H	H	H	H	NH2	345	42	36	554
  23	CO2Et	C7H5O2	H	H	H	H	Me	388	251
  275	CO2Et	C7H4BrO2	H	H	H	H	Me	467	263
  41	CO2Et	C4H3O	H	H	H	H	Me	334	271
  57	CO2Et	C7H7	H	H	H	H	Me	358	400
  67	CO2Me	C7H7	H	H	H	H	Me	344	39	128	1853
  66	CO2Me	C7H7	H	H	H	H	Me	344	46	151	1591
  85	CO2Me	C6H4Br	H	H	H	H	Me	431 (M +23)	35	>1000	5570
  82	CO2Me	C8H9	H	NH2	H	H	Me	373	294
  95	CO2Me	C11H9	H	H	H	H	NH2	395	286
  135	CO2Me	C5H4N	H	H	H	H	Me	331	123
  130	CO2Me	C6H6N	H	H	H	H	Me	345	222
  141	CO2Me	C6H5O	H	H	H	H	Me	346	172
  183	CO2Et	C8H10N	H	H	H	H	Me	387	191
  208	CO2Me	C7H4N	H	H	H	H	Me	355	171
  197	CO2Et	C6H5BrN	H	H	H	H	Me	437	148
  217	CO2Me	C7H6F	H	H	H	H	Me	362	119
  221	CO2Me	C6H5BrN	H	H	H	H	Me	423	76	258	2180
  222	CO2Me	2-Pyridyl	H	H	H	H	Me	353 (M +23)	237
  198	CO2Et	C7H8NO	H	H	H	H	Me	389	185
  199	CO2Et	C6H3I2O	H	H	H	H	Me	612	301
  279	CO2Me	C8H9	H		H	H	Me	513	179
  261	CO2Me	C8H9	H	H	C6H11N2O2	H	Me	500	472
  280	CO2Me	C8H9	H		H	H	Me	516	237
  276	CO2Me	C8H9	H	H	C5H6N3O	H	Me	481	304
  258	CO2Me	C8H9	H	C6H11N2O2	H	H	Me	500	211
  281	CO2Me	C8H9	H		H	H	Me	501	201
  262	CO2Me	C8H9	H	H	C6H12N3O	H	Me	499	332
  184	CO2Et	C7H8N	H	H	H	H	Me	373	140
  195	CO2Et	C6H4Cl2N	H	H	H	H	Me	427	171
  260	CO2Me	C8H9	H	C5H6N3O	H	H	Me	481	163
  263	CO2Me	C8H9	H	H	C2H4NO2	H	Me	431	480
  245	CO2Me	C8H9	H	H	C4H7N2O3	H	Me	488	276
  264	CO2Me	C7H5O2	H	H	H	H	NH2	397 (M +23)	342
  265	CO2Me	Ph	H	H	H	H	NH2	353 (M +23)	50
  267	CO2Me	2-Furyl	H	H	H	H	NH2	321	<15
  268	CO2Me	3-Furyl	H	H	H	H	NH2	321	21
  269	CO2Me	2-Furyl	H	H	H	H	Me	320	192
  270	CO2Me	2-Furyl	H	H	H	NH	Me	335	303
  271	CO2Me	2-Furyl	NH OH	H	H	H	Me	351	276
  272	CO2Et	H	H	H	H	NH2	335	<5
  273	CO2Et	H	Br	H	H	NH2	413	279
  274	CO2Et	H	H	Br	H	NH2	413	143

Claims (22)

1. A method of treating a subject having a disorder ameliorated by reducing PDE activity in appropriate cells, which comprises administering to the subject a therapeutically effective dose of a compound having the structure

wherein

(a) R₁ is selected from the group consisting of:

(i) —COR₅, wherein R₅ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;

wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁ are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;

(ii) COOR₆, wherein R₆ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;

 wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁, are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;

(iii) cyano;

(iv) a lactone or lactam formed with R₄;

(v) —CONR₇R₈ wherein R₇ and R₈ are independently selected from H, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, trifluoromethyl, hydroxy, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl;

wherein the alkyl, cycloalkyl, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl groups may be substituted with carboxyl, alkyl, aryl, substituted aryl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, hydroxamic acid, sulfonamide, sulfonyl, hydroxy, thiol, alkoxy or arylalkyl,

 or R₇ and R₈ taken together with the nitrogen to which they are attached form a heterocycle or heteroaryl group;

(vi) a carboxylic ester or carboxylic acid bioisostere including optionally substituted heteroaryl groups

(b) R₂ is selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocyclyl and optionally substituted C_3-7 cycloalkyl;

(c) R₃ is from one to four groups independently selected from the group consisting of:

(i) hydrogen, halo, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, aryl, heteroaryl, and heterocyclyl;

(ii) —NR₁₀R₁₁ wherein R₁₀ and R₁₁ are independently selected from H, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, carboxyalkyl, aryl, heteroaryl, and heterocyclyl or R₁₀ and R₁₁ taken together with the nitrogen form a heteroaryl or heterocyclyl group;

(iii) —NR₁₂COR₁₃ wherein R₁₂ is selected from hydrogen or alkyl and R_1-3 is selected from hydrogen, alkyl, substituted alkyl, C₁₃alkoxyl, carboxyalkyl, R₃₀R₃₁N (CH₂)_p—, R₃₀R₃₁NCO(CH₂)_p—, aryl, arylalkyl, heteroaryl and heterocyclyl or R₁₂ and R₁₃ taken together with the carbonyl form a carbonyl containing heterocyclyl group, wherein, R₃₀ and R₃₁ are independently selected from H, OH, alkyl, and alkoxy, and p is an integer from 1-6,

(d) R₄ is selected from the group consisting of (i) hydrogen, (ii) C_1-3 straight or branched chain alkyl, (iii) benzyl and (iv) —NR₁₃R₁₄, wherein R₁₃ and R₁₄ are independently selected from hydrogen and C_1-6 alkyl;

 wherein the C_1-3alkyl and benzyl groups are optionally substituted with one or more groups selected from C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, amino, NR₁₃R₁₄, aryl and heteroaryl; and

(e) X is selected from S and O;

with the proviso that when R₄ is isopropyl, then R₃ is not halogen, and the pharmaceutically acceptable salts, esters and pro-drug forms thereof.

2. A method of treating a subject having a disorder ameliorated by reducing PDE activity in appropriate cells, which comprises administering to the subject a therapeutically effective dose of a compound having the structure:

wherein

(a) R₁ is selected from the group consisting of:

(i) —COR₅, wherein R₅ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;

wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁ are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;

(ii) COOR₆, wherein R₆ is selected from H, optionally substituted C_1-8 straight or branched chain alkyl, optionally substituted aryl and optionally substituted arylalkyl;

wherein the substituents on the alkyl, aryl and arylalkyl group are selected from C_1-8 alkoxy, phenylacetyloxy, hydroxy, halogen, p-tosyloxy, mesyloxy, amino, cyano, carboalkoxy, or NR₂₀R₂₁ wherein R₂₀ and R₂₁ are independently selected from the group consisting of hydrogen, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, benzyl, aryl, or heteroaryl or NR₂₀R₂₁ taken together form a heterocycle or heteroaryl;

(i) cyano;

(ii) a lactone or lactam formed with R₄;

(iii) —CONR₇R₈ wherein R₇ and R₈ are independently selected from H, C_1-8 straight or branched chain alkyl, C_3-7 cycloalkyl, trifluoromethyl, hydroxy, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl;

wherein the alkyl, cycloalkyl, alkoxy, acyl, alkylcarbonyl, carboxyl, arylalkyl, aryl, heteroaryl and heterocyclyl groups may be substituted with carboxyl, alkyl, aryl, substituted aryl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, hydroxamic acid, sulfonamide, sulfonyl, hydroxy, thiol, alkoxy or arylalkyl,

 or R₇ and R₈ taken together with the nitrogen to which they are attached form a heterocycle or heteroaryl group;

(vi) a carboxylic ester or carboxylic acid bioisostere including optionally substituted heteroaryl groups

(b) R₂ is —NR₁₅R₁₆ wherein R₁₅ and R₁₆ are independently selected from hydrogen, optionally substituted C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, aryl, heteroaryl, and heterocyclyl or R₁₅ and R₁₆ taken together with the nitrogen form a heteroaryl or heterocyclyl group; with the proviso that when R₂ is NHR₁₆, R₁ is not —COOR₆ where R₆ is ethyl;

(c) R₃ is from one to four groups independently selected from the group consisting of:

(i) hydrogen, halo, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, aryl, heteroaryl, and heterocyclyl;

(ii) —NR₁₀R₁₁ wherein R₁₀and R₁₁ are independently selected from H, C_1-8 straight or branched chain alkyl, arylalkyl, C_3-7 cycloalkyl, carboxyalkyl, aryl, heteroaryl, and heterocyclyl or R₁₀ and R₁₁ taken together with the nitrogen form a heteroaryl or heterocyclyl group;

(iii) —NR₁₂COR₁₃ wherein R₁₂ is selected from hydrogen or alkyl and R₁₃ is selected from hydrogen, alkyl, substituted alkyl, C_1-3alkoxyl, carboxyalkyl, R₃₀R₃₁N (CH₂)_p—, R₃₀R₃₁NCO(CH₂)_p—, aryl, arylalkyl, heteroaryl and heterocyclyl or R₁₂ and R₁₃ taken together with the carbonyl form a carbonyl containing heterocyclyl group, wherein, R₃₀ and R₃₁, are independently selected from H, OH, alkyl, and alkoxy, and p is an integer from 1-6, wherein the alkyl group may be substituted with carboxyl, alkyl, aryl, substituted aryl, heterocyclyl, substituted heterocyclyl, heteroaryl, substituted heteroaryl, hydroxamic acid, sulfonamide, sulfonyl, hydroxy, thiol, alkoxy or arylalkyl;

(d) R₄ is selected from the group consisting of (i) hydrogen, (ii) C_1-3 straight or branched chain alkyl, (iii) benzyl and (iv) —NR₁₃R₁₄, wherein R₁₃ and R₁₄ are independently selected from hydrogen and C_1-6 alkyl;

 wherein the C_1-3alkyl and benzyl groups are optionally substituted with one or more groups selected from C_3-7 cycloalkyl, C_1-8 alkoxy, cyano, C_1-4 carboalkoxy, trifluoromethyl, C_1-8 alkylsulfonyl, halogen, nitro, hydroxy, trifluoromethoxy, C_1-8 carboxylate, amino, NR₁₃R₁₄, aryl and heteroaryl; and

(e) X is selected from S and O;

and the pharmaceutically acceptable salts, esters and pro-drug forms thereof.

3. A method of preventing a disorder ameliorated by reducing PDE activity in appropriate cells in a subject, comprising administering to the subject, in need of such treatment, a prophylactically effective dose of a compound as defined in claim 1 or claim 2 either preceding or subsequent to an event anticipated to cause a disorder ameliorated by reducing PDE activity in appropriate cells in the subject.

4. The method of claim 3 comprising administering to the subject a therapeutically or prophylactically effective dose of a pharmaceutical composition comprising a compound as defined in claim 1 or claim 2 and a pharmaceutically acceptable carrier.

5. The method of claim 3 comprising administering to the subject a therapeutically or prophylactically effective dose of the pharmaceutical composition comprising a compound as defined in claim 1 or claim 2 and a pharmaceutically acceptable carrier.

6. A method of inhibiting PDE activity in a subject, which comprises contacting one or more T-cells with a therapeutically effective dose of a compound as defined in claim 1 or claim 2.

7. The method of claim 1 or claim 2, wherein the disorder is selected from the group consisting of transplant-related disorders, inflammatory-related disorders, AIDS-related disorders, vascular diseases, and erectile dysfunction.

8. The method of claim 3, wherein the disorder is selected from the group consisting of transplant-related disorders, inflammatory-related disorders, AIDS-related disorders, vascular diseases, and erectile dysfunction.

9. The method of claim 6, wherein the disorder is selected from the group consisting of transplant-related disorders, inflammatory-related disorders, AIDS-related disorders, vascular diseases, and erectile dysfunction.

10. The method of claim 1 or claim 2, wherein the disorder is selected from the group consisting of hypersensitivity, allergy, arthritis, asthma, bee sting, animal bite, bronchospasm, dysmenorrhea, esophageal spasm, glaucoma, premature labor, a urinary tract disorder, inflammatory bowel disease, stroke, erectile dysfunction, HIV/AIDS, cardiovascular disease, gastrointestinal motility disorder, and psoriasis.

11. A method of artificially modifying an animal, comprising administering to the animal's T-cells a compound as defined in claim 1 or claim 2.

12. The method of claim 11 wherein the animal is a mammal.

13. The method of claim 12 wherein the animal is selected from the group consisting of mouse, rat, rabbit, and guinea pig.

14. A method of treating a subject having a disorder ameliorated by reducing PDE activity in appropriate cells, which comprises administering to the subject a therapeutically effective dose of a compound having the structure of Formula I wherein R₄ is C_1-8 straight or branched chain alkyl and X is O.

15. A method of treating a subject having a disorder ameliorated by antagonizing Adenosine A2a receptors in appropriate cells in the subject, which comprises administering to the subject a therapeutically effective dose of a compound as defined in claim 1 or claim 2.

16. A method of preventing a disorder ameliorated by antagonizing Adenosine A2a receptors in appropriate cells in the subject, comprising administering to the subject a prophylactically effective dose of a compound as defined in claim 1 or claim 2, either preceding or subsequent to an event anticipated to cause a disorder ameliorated by antagonizing Adenosine A2a receptors in appropriate cells in the subject.

17. The method of claim 15 comprising administering to the subject a therapeutically or prophylactically effective dose of a pharmaceutical composition comprising the compound as defined in claim 1 or claim 2 and a pharmaceutically acceptable carrier.

18. The method of claim 16 comprising administering to the subject a therapeutically or prophylactically effective dose of the pharmaceutical composition comprising a compound as defined in claim 1 or claim 2 and a pharmaceutically acceptable carrier.

19. The method of claim 15 or claim 17, wherein the disorder is a neurodegenerative disorder or a movement disorder.

20. The method of claim 19, wherein the disorder is selected from the group consisting of Parkinson's Disease, Huntington's Disease, Multiple System Atrophy, Corticobasal Degeneration, Alzheimer's Disease, and Senile Dementia.

21. The method of claim 16, wherein the disorder is a neurodegenerative disorder or a movement disorder.

22. The method of claim 21, wherein the disorder is selected from the group consisting of Parkinson's Disease, Huntington's Disease, Multiple System Atrophy, Corticobasal Degeneration, Alzheimer's Disease, and Senile Dementia.