Patent ID: 8263648

Claim:
A compound of formula and its tautomers, stereoisomers, enantiomers, diastereomers, and pharmaceutically acceptable salts wherein R 1 is X 1 is selected from hydrogen, optionally substituted alkyl, optionally substituted N,N-dimethylaminoalkenyl, carboxy, ═CH—NR 5 R 6 , COOR 6 ; X 2 is selected from optionally halo, cyano, carboxy, COOR 6 , substituted alkyl, NR 5 R 6 , —NR 5 S(O) m R 6 ; X 4 represents O, S, NR 5 , N—OR 5 , ═N—OCH 2 COOH, ═N—O-Me; when X 1 and X 2 or X 1 and X 4 ; are ortho to each other, they may together form a 4 to 7 membered ring system selected from an alicyclic or heterocyclic ring; r is 0 or 1; R 2 represents optionally substituted groups selected from alkyl, haloalkyl, alkenyl, alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heteroaryl or optionally substituted heterocyclyl; R 5 represents hydrogen, alkoxy, R′COOR 6 , optionally substituted alkyl or optionally substituted aryl; R 6 represents hydrogen, optionally substituted alkyl or optionally substituted aryl; R 5 and R 6 may together form a 3 to 12 membered mono or polycyclic ring; R′ represents a direct bond or an optionally substituted alkylene; m is an integer represented by 0, 1 or 2.