Patent ID: 8273878

Claim:
A compound of Formula (2a), and tautomers thereof: wherein R 1 is H or an alkyl group; R 2 is H, an alkyl or aryl group; R 3 and R 4 are each independently H, alkyl, or aryl, provided that R 3 and R 4 are not both unsubstituted alkyl; and E represents a group of formula CO 2 (C 1-4 alkyl), further provided that R 1 is not —CH 3 when R 2 is unsubstituted phenyl or o-nitrophenyl, and wherein optional substitutents for alkyl, aryl or heteroaryl groups R 1 , R 2 , R 3 or R 4 are selected from optionally substituted C 1-4 -alkyl, optionally substituted aryl, optionally substituted aryloxy, optionally substituted heterocyclyl, polyalkylene oxide, carboxy, oxo, phosphato, sulpho, nitro, cyano, halo, ureido, —SO 2 F, ester, NR a R b , COR a , CONR a R b , —NHCOR a , carboxyester, sulphone, and —SO 2 NR a R b wherein R a and R b are each independently H, optionally substituted alkyl C 1-4 -alkyl) or optionally substituted aryl, or, in the case of NR a R b , —CONR a R b and —SO 2 R a R b , R a and R b together with the nitrogen atom to which they are attached may represent an aliphatic or aromatic ring system and wherein optional substituents for any of the substituents described may be selected from C 1-4 -alkoxy, C 1-4 -alkyl, aryl, aryloxy, heterocyclyl, polyalkylene oxide, carboxy, oxo, phosphato, sulpho, nitro, cyano, halo, ureido, —SO 2 F, hydroxy, ester, NR a R b , COR a , CONR a R b , —NHCOR a , carboxyester, sulphone, and —SO 2 NR a R b wherein R a and R b are each independently H, C 1-4 -alkyl or aryl, or, in the case of NR a R b , —CONR a R b and —SO 2 NR a R b , R a and R b together with the nitrogen atom to which they are attached may represent an aliphatic or aromatic ring system.