Patent ID: 8420851

Claim:
A compound of formula (I) or a tautomer or pharmaceutically acceptable salt thereof wherein, R is selected from OR 1 , and NHR 1 , wherein R 1 is selected from H, or an optionally substituted group selected from (C 1 -C 6 )alkyl, and ar(C 1 -C 6 )alkyl groups; R 2 represents hydrogen, hydroxyl, halo, or an optionally substituted group selected from (C 1 -C 6 )alkyl, acyl, oxo, (C 3 -C 7 )cycloalkyl, aryl, heteroaryl, alkoxy, aryloxy, aralkyl, aralkoxy, carboxylic acid and its derivatives selected from (C 1 -C 3 )alkyl esters and amides; sulfenyl derivatives, sulfonyl derivatives or a group —CONR 5 R 6 , or —SO 2 NR 5 R 6 , wherein R 5 and R 6 are the same or different and are independently selected from H, or optionally substituted groups selected from (C 1 -C 6 )alkyl, (C 3 -C 7 )cycloalkyl, bicycloalkyl, aryl or R 5 and R 6 together with the nitrogen atom to which they are attached, form a five to eight membered cyclic ring which may optionally contain one or more additional hetero atoms selected from N, S, and O; R 3 , and R 4 are same or different and are independently selected from H, halogen, or optionally substituted (C 1 -C 6 )alkyl groups; X is selected from O, —CH 2 —, and CO; n represents 0 or 1; R 7 represents H, or an optionally substituted group selected from (C 1 -C 6 )alkyl, and aryl groups; with the provision that when n is 0, R 7 does not represent H.