Heterocyclic compounds as phosphodiesterase inhibitors

1. Compound of formula (I),

their tautomeric forms, regioisomers, stereoisomers, solvates and pharmaceutically acceptable salts thereof;

wherein:

X represents O, S;

Y represents O;

R 3 , R 4 and R 5 independently represent hydrogen, halogens, haloalkyl, nitro, cyano, hydroxy, substituted or unsubstituted groups selected from alkyl, alkylthio, alkoxy, aryl, aryloxy, aralkyl, alkenyl, alkynyl, aralkenyl, aralkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, heteroaryl, heteroarylalkyl, —(CH 2 ) m —C(O)NR 7 R 8 , amino, imino, alkylamino, cycloalkylamino, arylamino, aralkylamino, alkanoyl, aroyl, aralkanoyl, sulfonyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl, alkylsulfonamido, —COOR 7 , —C(O)R 7 , —C(S)R 7 , —C(O)NR 7 R 8 , —NR 7 C(O)NR 7 R 8 , —N(R 7 )SOR 8 , —N(R 7 )SO 2 R 8 , —NR 7 C(O)OR 8 , —NR 7 R 8 , —NR 7 C(O)R 8 , —NR 7 C(S)R 8 , —SONR 7 R 8 , —SO 2 NR 7 R 8 ; —OR 7 , —OR 7 C(O)OR 8 , —CONR 7 OR 8 , —OC(O)R 7 , —OC(O)NR 7 R 8 , —R 7 NR 7 R 8 , —R 7 OR 8 , —SR 7 , —SOR 7 and —SO 2 R 7 ; R 7 and R 8 each independently represents hydrogen, substituted or unsubstituted groups selected from alkyl, aryl, aralkyl, cycloalkyl, heterocyclyl, heteroaryl and heteroarylalkyl or R 7 and R 8 can be combined together to form an substituted or unsubstituted 3-7 membered ring having 0-2 hetero atoms;

R 1 represents hydrogen, halogens, haloalkyl, nitro, cyano, hydroxy, substituted or unsubstituted groups selected from alkyl, alkylthio, alkoxy, aryl, aryloxy, aralkyl, alkenyl, alkynyl, aralkenyl, aralkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, heteroarylalkyl, —(CH 2 ) m —C(O)NR 7 R 8 , amino, imino, alkylamino, cycloalkylamino, arylamino, aralkylamino, alkanoyl, aroyl, aralkanoyl, sulfonyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl, alkylsulfonamido, —COOR 7 , —C(O)R 7 , —C(S)R 7 , —C(O)NR 7 R 8 , —NR 7 C(O)NR 7 R 8 , —N(R 7 )SOR 8 , —N(R 7 )SO 2 R 8 , —NR 7 C(O)OR 8 , —NR 7 R 8 , —NR 7 C(O)R 8 , —NR 7 C(S)R 8 , —SONR 7 R 8 , —SO 2 NR 7 R 8 ; —OR 7 , —OR 7 C(O)OR 8 , —CONR 7 OR 8 , —OC(O)R 7 , —OC(O)NR 7 R 8 , —R 7 NR 7 R 8 , —R 7 OR 8 , —SR 7 , —SOR 7 and —SO 2 R 7 ; R 7 and R 8 each independently represents hydrogen, substituted or unsubstituted groups selected from alkyl, aryl, aralkyl, cycloalkyl, heterocyclyl, heteroaryl and heteroarylalkyl or R 7 and R 8 can be combined together to form an substituted or unsubstituted 3-7 membered ring having 0-2 hetero atoms;

R 2 represents substituted or unsubstituted groups selected from alkyl, haloalkyl and cycloalkyl;

R 4 and R 5 can be combined together to form a substituted or unsubstituted 5 to 7 membered ring, having 0-3 heteroatoms selected from 0, N and S;

represents a double bond or a single bond;

A or B represents —CR 6 —, —NR 6 —, ═N—, —O— or —S—; when one of A or B represents —CR 6 —, then the other represents —NR 6 —, ═N—, —O— or —S—;

R 6 represents hydrogen, substituted or unsubstituted groups selected from alkyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, aralkyl, alkenyl, alkynyl, aralkenyl, aralkynyl, heterocyclyl and heteroaryl; and

m and n are integers independently selected from 0, 1, 2, 3 or 4;

wherein the term “substituted” refers to substitution with any one or any combination of the following substituents: halogens; hydroxy; nitro; cyano; oxo (═O); thioxo (═S); azido; nitroso; amino; hydrazino; formyl; alkyl; haloalkyl groups; haloalkoxy; arylalkoxy groups; cycloalkyl; —O-cycloalkyl; aryl; alkoxy; heterocyclyl; heteroaryl; alkylamino; —O—CH 2 -cycloalkyl; —COOR a ; —C(O)R b ; —C(S)R a ; —C(O)NR a R b ; —NR a C(O)NR b R c ; —N(R a )SOR b ; —N(R a )SO 2 R b ; —NR a C(O)OR b ; —NR a R b ; —NR a C(O)R b ; —NR a C(S)R b ; —SONR a R b ; —SO 2 NR a R b ; —OR a ; —OR a C(O)OR b ; —OC(O)NR a R b ; —OC(O)R a ; —R a NR b R c ; —R a OR b ; —ST a ; —SOR a and —SO 2 R a ; R a , R b and R c each independently represents hydrogen atom; substituted or unsubstituted groups selected from alkyl; alkylene; aryl; aralkyl; cycloalkyl; heterocyclyl; heteroaryl and heteroarylalkyl; R a , R b and R c can be combined together to form a 3-7 membered ring having 0-2 hetero atoms; the substituents are further optionally substituted by one or more substituents as defined above.

2. The compound according to claim 1 , wherein: when alkyl group is present, the alkyl group is methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl or octyl; when alkenyl group is present, the alkenyl group is ethenyl, 1-propenyl, 2-propenyl, iso-propenyl, 2-methyl-1-propenyl, 1-butenyl or 2-butenyl; when the alkynyl group is present, the alkynyl group is ethynyl, propynyl or butynyl; when haloalkyl group is present, the haloalkyl group is difluoromethyl, dichloromethyl, trifluoromethyl, tribromomethyl or trichloromethyl; when haloalkoxy group is present, the haloalkoxy group is selected from chloromethoxy, chloroethoxy, difluoromethoxy, dichloromethoxy, trifluoromethoxy, trifluoroethoxy and trichloromethoxy; when aryl group is present, the aryl group is phenyl, naphthyl, anthracenyl, indanyl or biphenyl; when alkoxy group is present, the alkoxy group is selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy or t-butoxy; when aryloxy group is present, the aryloxy group is selected from phenoxy or naphthyloxy; when aralkyl group is present, the aralkyl group is —CH 2 C 6 H 5 or —C 2 H 4 C 6 H 5 ; when aralkenyl group is present, the aralkenyl group is phenylethenyl or phenylpropenyl; when aralkynyl group is present, the aralkynyl group is phenylethynyl or phenylpropynyl; when alkanoyl group is present, the alkanoyl group is acetyl, propanoyl or butanoyl; when aroyl group is present, the aroyl group is benzoyl or naphthoyl; when aralkanoyl group is present, the aralkanoyl group is phenylacetyl, phenylpropanoyl, naphthylacetyl or naphthylpropanoyl; when heterocyclyl or heteroaryl group is present, the heterocyclyl or heteroaryl group is selected from azetidinyl, acridinyl, benzodioxolyl, benzodioxanyl, benzofuranyl, carbazolyl, cinnolinyl, dioxolanyl, dibenzofuranyl, indolizinyl, naphthyridinyl, perhydroazepinyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pyridyl, pteridinyl, purinyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrazolyl, imidazolyl, tetrahydroisoquinolinyl, 2-oxoazepinyl, azepinyl, pyrrolyl, piperonyl, pyrrolidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, oxazolyl, oxazolinyl, triazolyl, isoxazolyl, isoxazolidinyl, thiazolyl, thiazolinyl, thiazolidinyl, thienyl, isothiazolyl, quinuclidinyl, isothiazolidinyl, indolyl, isoindolyl, indolinyl, isoindolinyl, octahydroindolyl, octahydroisoindolyl, decahydroisoquinolyl, benzimidazolyl, thiadiazolyl, benzopyranyl, benzothiazolyl, benzothiadiazolyl, benzoxadiazolyl, benzotriazolyl, benzothienyl, benzoxazolyl, oxadiazolyl, benzindazolyl, indazolyl, phenyl piperidinyl, furyl, tetrahydrofuryl, tetrahydropyranyl, piperazinyl, homopiperazinyl, piperidyl, piperidopiperidyl, morpholinyl, thiomorpholinyl, piperidonyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, chromanyl and isochromanyl; when cycloalkyl group is present, the cycloalkyl group is cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cycloheptyl, perhydronaphthyl, adamantyl, bridged cyclic groups or spirobicyclic groups; when cycloalkenyl group is present, the cycloalkenyl group is cyclopropenyl or cyclopentenyl; when cycloalkynyl group is present, the cycloalkynyl group is cyclopropynyl or cyclopentynyl; when alkylsulfonyl group is present, the alkylsulfonyl group is methylsulfonyl, ethylsulfonyl, n-propylsulfonyl or isopropylsulfonyl; when arylsulfonyl group is present the arylsulfonyl group is phenylsulfonyl or naphthylsulfonyl; when alkylthio group is present, the alkylthio group is —SCH 3 or —SC 2 H 5 ; when alkylamino group is present, the alkylamino group is —NHCH 3 or —N(CH 3 ) 2 and when arylamino group is present, the arylamino group is phenylamino or naphthylamino.

3. A compound of formula (I) as defined in claim 1 selected from the compounds consisting of:

Ethyl 6-(2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)picolinate;

6-(2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)picolinic acid;

Ethyl 6-(2-(4-ethoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)picolinate;

6-(2-(4-Ethoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)picolinic acid;

Ethyl 6-(2-(4-(difluoromethoxy)dibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)picolinate;

6-(2-(4-(Difluoromethoxy)dibenzo[h,d]furan-1-yl)-1,3-thiazol-4-yl)picolinic acid;

4-(2-(4-Methoxydibenzo[M]furan-1-yl)-1,3-thiazol-4-yl)benzonitrile;

6-(2-(4-Methoxydibenzo[b,d]furan-2-yl)-1,3-thiazol-4-yl)picolinic acid;

6-(2-(4-Methoxy-8-(methylsulfonamido)dibenzo[b,d]furan-2-yl)-1,3-thiazol-4-yl)picolinic acid;

N-(3,5-Dichloropyridin-4-yl)-3-(2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)propanamide;

N-(3,5-Dichloropyridin-4-yl)-2-(2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)acetamide;

N-(3,5-Dichloropyridin-4-yl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

N-(3,5-Dichloropyridin-4-yl)-2-(4-(difluoromethoxy)dibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

Ethyl 2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxylate;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxylic acid;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-N-phenyl-1,3-thiazole-4-carboxamide;

(2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)(4-(pyrimidin-2-yl)piperazin-1-yl)methanone;

(2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)(4-(pyridin-2-yl)piperazin-1-yl)methanone;

N-(4-Chlorophenyl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

Ethyl2-(4-methoxydibenzo[b,d]furan-1-yl)-4-methyl-1,3-thiazole-5-carboxylate;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-4-(4-methoxyphenyl)-1,3-thiazole;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-4-methyl-1,3-thiazole-5-carboxylic acid;

N-(3,5-Dichloropyridin-4-yl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-4-methyl-1,3-thiazole-5-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

N-Cyclopentyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-thiazole-4-carboxamide;

N-(4-Hydroxycyclohexyl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-thiazole-4-carboxamide;

N-(3,5-Dichloropyridin-4-yl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-thiazole-4-carboxamide;

N-Ethyl-2-(4-methoxydibenzo[b,d]furan-1-yl]-5-methyl-1,3-thiazole-4-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-N-morpholino-1,3-thiazole-4-carboxamide;

N-(4-Hydroxycyclohexyl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

2-[4-(Difluoromethoxy)-8-nitrodibenzo[b,d]furan-1-yl]-5-methyl-1,3-thiazole-4-carboxylic acid;

2-(4-(Difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-5-methyl-1,3-thiazole-4-carboxylic acid;

N-(3,5-Dichloropyridin-4-yl)-2-(4-(difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-1,3-thiazole-4-carboxamide;

2-(4-(Difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-5-methyl-1,3-thiazole-4-carboxamide;

2-[8-(Acetylamino)-4-(difluoromethoxy)dibenzo[b,d]furan-1-yl]-1,3-thiazole-4-carboxylic acid;

2-(4-(Difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-N-methoxy-5-methyl-1,3-thiazole-4-carboxamide;

2-(8-Acetamido-4-(difluoromethoxy)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-1,3-thiazole-4-carboxamide;

2-((4-Difluoromethoxy)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-1,3-thiazole-4-carboxamide;

2-((4-Difluoromethoxy)dibenzo[b,d]furan-1-yl)-N-(2,2,2-trifluoroethyl)-1,3-thiazole-4-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-N-(2,2,2-trifluoroethyl)-1,3-thiazole-4-carboxamide;

2-((4-Difluoromethoxy)dibenzo[b,d]furan-1-yl)-N-methoxy-1,3-thiazole-4-carboxamide;

2-[4-(Difluoromethoxy)-8-(trifluoromethyl)dibenzo[b,d]furan-1-yl]-1,3-thiazole-4-carboxylic acid;

2-(4-(Difluoromethoxy)-8-(trifluoromethyl)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-1,3-thiazole-4-carboxamide;

(2-(4-(Difluoromethoxy)-8-(trifluoromethyl)dibenzo[b,d]furan-1-yl)-1,3-thiazol-4-yl)(4-hydroxypiperidin-1-yl)methanone;

2-(4-(Difluoromethoxy)-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-1,3-thiazole-4-carboxamide;

Ethyl 2-(4-(difluoromethoxy)-8-nitrodibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxylate;

Ethyl 2-(4-(difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxylate;

2-(4-(Difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxylic acid;

2-(4-(Difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-N-(4-hydroxycyclohexyl)-1,3-oxazole-4-carboxamide;

N-Cyclopropyl-2-(4-(difluoromethoxy)-8-[(methylsulfonyl)amino]dibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxamide;

N-Cyclopentyl-2-(4-(difluoromethoxy)-8-(methylsulfonamido)dibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxamide;

Ethyl 2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxylate;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxylic acid;

N-(3,5-Dichloropyridin-4-yl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

N-Cyclopropyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

N-Ethyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

N-Cyclopentyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

N-(4-Hydroxycyclohexyl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-5-methyl-1,3-oxazole-4-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-5-methyl-N-(propan-2-yl)-1,3-oxazole-4-carboxamide;

Ethyl 2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxylate;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxylic acid;

Ethyl 2-(4-(2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carbonyl)piperazin-1-yl)pyrimidine-5-carboxylate;

N-(3,5-Dichloropyridin-4-yl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxamide;

2-(4-(2-(4-Methoxydibenzo[b,d]furan-1-yl)oxazole-4-carbonyl)piperazin-1-yl)pyrimidine-5-carboxylic acid;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxamide;

[2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-oxazol-4-yl](4-(pyrimidin-2-yl piperazin-1-yl)methanone;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-N-methyl-1,3-oxazole-4-carboxamide;

N-Cyclopropyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-oxazole-4-carboxamide;

[2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-oxazol-4-yl](pyrrolidin-1-yl)methanone;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-benzo[d]oxazole-5-carboxylic acid;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-benzo[d]oxazole-5-carboxamide;

2-(4-Methoxydibenzo[b,d]furan-1-yl)-1,3-benzo[d]oxazole;

2-(4-Methoxydibenzo[b,d]furan-1-yl)[1,3]oxazolo[4,5-b]pyridine;

N-Cyclopentyl-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-benzo[d]oxazole-5-carboxamide; and

N-(4-Hydroxycyclohexyl)-2-(4-methoxydibenzo[b,d]furan-1-yl)-1,3-benzo[d]oxazole-5-carboxamide, or their pharmaceutically acceptable salts.

4. A pharmaceutical composition comprising a compound of formula (I) as claimed in claim 1 , as an active ingredient along with a pharmaceutically acceptable carrier, diluent or excipient.

5. A pharmaceutical composition as claimed in claim 4 , wherein the said composition is in the form of a tablet, capsule, powder, syrup, solution, aerosol or suspension.

6. A method of treating allergic or inflammatory diseases selected from asthma, COPD, chronic bronchitis, atopic dermatitis, allergic rhinitis, allergic conjunctivitis, vernal conjuctivitis, psoriasis, rheumatoid arthritis, ulcerative colitis, Crohn's disease, uveitis, NASH and lupus comprising administering an effective amount of a compound according to claim 1 , to a mammal in need thereof.

7. A method of treatment of inflammatory diseases selected from asthma, COPD and chronic bronchitis comprising administering an effective amount of a compound according to claim 1 , to a mammal in need thereof.

8. A pharmaceutical composition comprising a compound of formula (I) as claimed in claim 3 , as an active ingredient along with a pharmaceutically acceptable carrier, diluent or excipient.

9. A method of treating allergic or inflammatory diseases selected from asthma, COPD, chronic bronchitis, atopic dermatitis, allergic rhinitis, allergic conjunctivitis, vernal conjuctivitis, psoriasis, rheumatoid arthritis, ulcerative colitis, Crohn's disease, uveitis, NASH and lupus comprising administering an effective amount of a compound according to claim 3 , to a mammal in need thereof.

10. A method of treatment of inflammatory diseases selected from asthma, COPD and chronic bronchitis comprising administering an effective amount of a compound according to claim 3 , to a mammal in need thereof.