Pyrimidone derivatives

1. A pyrimidone of the formula (I)

or its pharmaceutically acceptable salt, wherein X represents oxygen, sulfur or NR, wherein R represents hydrogen, hydroxyl, acyl, alkyl, alkoxy, aryl, amino, hydroxylamino, alkylamino, arylamino, acylamino, alkoxyamino group; the rings represented by A and B are selected from aryl or heteroaryl; R 1 and R 3 may be same or different and independently represent hydrogen, SR 7 , S(O) p R 8 ; R 2 and R 4 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, alkyl, haloalkyl, acyl, alkoxy, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or carboxylic acids; R 5 and R 6 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, aralkyl, haloalkyl, acyl, alkoxy, aryloxy, aralkoxy, heteroaryl, heterocyclyl, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or COR 9 ; R 7 represents hydrogen, alkyl or aryl; R 8 represents halogen, alkyl, amino, acylamino, arylamino or aryl group; R 9 represents hydrogen, hydroxyl, amino, halogen, alkyl, alkoxy, aryloxy, monoalkylamino, dialkylamino, acylamino, arylamino, groups; m is an integer and is in the range of 1 to 4; n is an integer and is in the range of 1 to 4; p represents an integer of 1 or 2.

2. The pyrimidone of the formula (I) as claimed in claim 1 , wherein the ring systems represented by a and B are selected from phenyl, naphthyl, pyridyl, thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, pyrimidinyl, benzopyranyl, benzofuranyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzopyrrolyl, benzoxadiazolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, benzothienyl, benzofuranyl or indolyl.

3. A pyrimidone selected from:

5-Cyano-2-(4-chlorophenyl)-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-(4-fluorophenyl)-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-phenyl-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-(trifluoromethylphenyl)-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-[(4-methylthio)phenyl]-4-(methylthio)-1-[4-fluorophenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-methylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-[(4-methylsulphonyl)phenyl]-4-(methylthio)-1-[4-methylphenyl]-6-oxo-1,6-dihydropyrimidine;

5-Carboxy-2-[(4-methylthio)phenyl]-4-(methylthio)-1-[4-methylphenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-isopropylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(3,4-dimethylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-isopropylphenyl)-2-[4-(methylsulfonyl)phenyl]-4-(methylthio)-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(3,4-dimethylphenyl)-2-[4-(methylsulfonyl)phenyl]-4-(methylthio)-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(3,4,5-trimethoxyphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-ethylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

1-(4-Bromophenyl)-5-cyano-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-methoxyphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-fluorophenyl)-4-(methylthio)-2-phenyl-6-oxo-1,6-dihydropyrimidine;

1-(4-Chlorophenyl)-5-cyano-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(2,4-dimethylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-(4-methylphenyl)-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-methoxyphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

1-(4-tert-Butylphenyl)-5-cyano-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-methylphenyl)-4-(methylthio)-6-oxo-2-phenyl-1,6-dihydropyrimidine;

1-(4-n-Butylphenyl)-5-cyano-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(4-fluorophenyl)-4-(methylthio)-6-oxo-2-pyridin-4-yl-1,6-dihydropyrimidine;

5-Cyano-1-(4-fluorophenyl)-4-(methylthio)-6-oxo-2-pyridin-3-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-2-pyridin-3-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-2-pyridin-4-yl-1,6-dihydropyrimidine;

5-Cyano-1-(4-fluorophenyl)-4-(methylthio)-6-oxo-2-pyridin-2-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-2-pyridin-2-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-methoxyphenyl)-6-oxo-2-pyridin-2-yl-1,6- dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(3,4-dimethylphenyl)-6-oxo-2-pyridin-2-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-ethylphenyl)-6-oxo-2-pyridin-2-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-methylphenyl)-6-oxo-2-pyridin-2-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-ethoxyphenyl)-6-oxo-2-pyridin-4-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-methylphenyl)-6-oxo-2-pyridin-4-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-isopropylphenyl)-6-oxo-2-pyridin-4-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-ethylphenyl)-6-oxo-2-pyridin-3-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(3,4-dimethylphenyl)-6-oxo-2-pyridin-3-yl-1,6-dihydropyrimidine;

5-Cyano-4-(methylthio)-1-(4-methoxyphenyl)-6-oxo-1-pyridin-3-yl-1,6-dihydropyrimidine;

Ethyl 1-(4-methylphenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine-5-carboxylate;

Ethyl 1-(4-fluorophenyl)-4-(methylthio)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine-5-carboxylate;

Ethyl 2-(4-fluorophenyl)-4-(methylthio)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine-5-carboxylate;

5-Carboxamido-1-(4-methylphenyl)-4-(methylsulfonyl)-2-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-1-(4-methylphenyl)-2-[4-(methylsulfonyl)phenyl]-6-oxo-4-piperazin-1-yl-1,6-dihydropyrimidine;

5-Carboxamido-4-(methylamino)-1-(4-methylphenyl)-2-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-1-(4-methylphenyl)-2-[4-(methylsulfonyl)phenyl]-4-morpholin-4-yl-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-2-(4-fluorophenyl)-4-(methylsulfonyl)-1-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-2-(4-fluorophenyl)-4-(methylamino)-1-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-2-(4-fluorophenyl)-1-[4-(methylsulfonyl)phenyl]-4-morpholin-4-yl-6-oxo-1,6-dihydropyrimidine;

5-Carboxamido-1-(3,4-dimethylphenyl)-4-(methylsulfonyl)-2-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-(4-fluorophenyl)-4-hydroxy-1-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(3,4-dimethylphenyl)-4-hydroxy-2-[4-(methylsulfonyl)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-4-(methylamino)-1-(4-methylphenyl)-2-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-1-(3,4-dimethylphenyl)-4-(methylamino)-2-[4-(methylthio)-phenyl]-6-oxo-1,6-dihydropyrimidine;

5-Cyano-2-(4-fluorophenyl)-4-(methylamino)-1-[4-(methylthio)phenyl]-6-oxo-1,6-dihydropyrimidine;

4-[5-Cyano-1-(3,4-dimethylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]benzenesulfonyl chloride;

4-[5-Cyano-2-(4-ethoxyphenyl)-4-(methylthio)-6-oxopyrimidin-1(6H)-yl]benzenesulfonyl chlorid;

4-[5-Cyano-1-(4-methylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]benzenesulfonamide;

N-({4-[5-Cyano-1-(4-methylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)acetamide;

N-({4-[5-Cyano-1-(3,4-dimethylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)acetamide;

N-({4-[5-Cyano-1-(4-methylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)-2,2,2-trifluoroacetamide;

N-({4-[5-Cyano-1-(3,4-dimethylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)-2,2,2-trifluoroacetamide;

N-({4-[5-Cyano-1-(4-methylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)benzamide and

N-({4-[5-Cyano-1-(3,4-dimethylphenyl)-4-(methylthio)-6-oxo-1,6-dihydropyrimidin-2-yl]phenyl}sulfonyl)benzamide.

4. A process for the preparation of a pyrimidone of the formula (I)

or its pharmaceutically acceptable salt, wherein X represents oxygen, sulfur or NR, wherein R represents hydrogen, hydroxyl, acyl, alkyl, alkoxy, aryl, amino, hydroxylamino, alkylamino, arylamino, acylamino, alkoxyamino group; the rings represented by A and B are selected from aryl or hereroaryl; r 1 and R 3 may be same or different and independently represent hydrogen, SR 7 , S(O) p R 8 ; R 2 and R 4 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, alkyl, haloalkyl, acyl, alkoxy, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or carboxylic acids; R 5 and R 6 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, aralkyl, haloalkyl, acyl, alkoxy, aryloxy, aralkoxy, heteroaryl, heterocyclyl, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or COR 9 ; R 7 represents hydrogen, alkyl or aryl; R 8 represents halogen, alkyl, amino, acylamino, arylamino or aryl group; R 9 represents hydrogen, hydroxyl, amino, halogen, alkyl, alkoxy, aryloxy, monoalkylamino, dialkylamino, acylamino, arylamino, groups; m is an integer and is in the range of 1 to 4; n is an integer and is in the range of 1 to 4; p represents an integer of 1 or 2; which comprises reacting a compound of the formula (Ia)

where R represent (C 1 -C 3 ) alkyl group, X, R 5 and R 6 are as defined above, with a compound of the formula (Ib)

wherein all symbols are as defined above, to produce a compound of formula (I).

5. A process for the preparation of a pyrimidone of the formula (I)

or its pharmaceutically acceptable salt, wherein X represents oxygen, sulfur or NR, wherein R represents hydrogen, hydroxyl, acyl, alkyl, alkoxy, aryl, amino, hydroxylamino, alkylamino, arylamino, acylamino, alkoxyamino group; the rings represented by A and B are selected from aryl or heteroaryl; R 1 and R 3 may be same or different and independently represent hydrogen, SR 7 , S(O) p R 8 ; R 2 and R 4 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, alkyl, haloalkyl, acyl, alkoxy, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or carboxylic acids; R 5 and R 6 may be same or different and independently represent halogen, hydroxyl, nitro, cyano, azido, nitroso, amino, formyl, aralkyl, haloalkyl, acyl, alkoxy, aryloxy, aralkoxy, heteroaryl, heterocyclyl, monoalkylamino, dialkylamino, acylamino, alkoxycarbonyl, SR 7 , S(O) p R 8 , alkoxyalkyl groups or COR 9 ; R 7 represents hydrogen, alkyl or aryl; R 8 represents halogen, alkyl, amino, acylamino, arylamino or aryl group; R 9 represents hydrogen, hydroxyl, amino, halogen, alkyl, alkoxy, aryloxy, monoalkylamino, dialkylamino, acylamino, arylamino, groups; m is an integer and is in the range of 1 to 4; n is an integer and is in the range of 1 to 4; p represents an integer of 1 or 2; with a proviso that when R 1 represents hydrogen R 2 is not hydrogen, which comprises reacting a compound of the formula (Ic)

where R represent (C 1 -C 3 ) alkyl group and all other symbols are as defined above, with a compound of the formula (Id)

wherein all symbols are as defined above, to produce a compound of formula (I).

6. A process for the conversion of the pyrimidone of the formula (I) as claimed in claim 1 ,

wherein any one of the groups R 1 and R 3 represent SR 7 , wherein R 7 represents alkyl or aryl and all other symbols are as defined in claim 1 , to pyrimidones of the formula (I) wherein any one of the groups R 1 and R 3 represent S(O) p R 8 , where p represents 1 or 2 and R 8 represents alkyl or aryl, and all other symbols are as defined above, using an oxidizing agent.

7. A process for the conversion of the pyrimidone of the formula (I) as claimed in claim 1 ,

wherein either of the groups R 1 or R 3 represent S(O) p R 8 , wherein R 8 represents amino group and p represents an integer of 1 or 2 and all other symbols are as defined in claim 1 , which comprises reacting compound of formula (Ie)

wherein R 1 or R 3 represents hydrogen and all other symbols are as defined in claim 1 , with chlorosulfonic acid and ammonia.

8. A pharmaceutical composition which comprises a compound of formula (I)

as defined in claim 1 and a pharmaceutically acceptable carrier, diluent, excipient or solvate.

9. A pharmaceutical composition as claimed in claim 8 , in the form of a tablet, capsule, powder, syrup, aerosol, solution or suspension.

10. A pharmaceutical composition which comprises a compound as claimed in claim 3 and a pharmaceutically acceptable carrier, diluent, excipient or solvate.

11. A pharmaceutical composition as claimed in claim 10 , in the form of a tablet, capsule, powder, syrup, aerosol, solution or suspension.

12. A method of treating a condition selected from the group consisting of rheumatoid arthritis; lung cancer, breast cancer and central nervous system cancer; inflammatory bowel disease; and psoriasis comprising administering the compound of formula (I) as claimed in claim 1 in a pharmaceutically effective amount to a subject afflicted with one or more of the foregoing conditions and in need of treatment.

13. A method of treating a condition selected from the group consisting of rheumatoid arthritis; lung cancer, breast cancer and central nervous system cancer; inflammatory bowel disease; and psoriasis comprising administering the compound as claimed in claim 3 in a pharmaceutically effective amount to a subject afflicted with one or more of the foregoing conditions and in need of treatment.

14. A method of treating a condition selected from the group consisting of rheumatoid arthritis, and psoriasis comprising administering the composition as claimed in claim 8 in a pharmaceutically effective amount to a subject afflicted with one or more of the foregoing conditions in need of treatment.