| abstract |
A compound, which is a compound of formula (1-1) or a salt thereof: **(See formula)** wherein Ra1 each independently is halogen; cyan; nitre; C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylamino, di(C1-C6 alkyl)amino, carbamoyl or sulfamoyl, each optionally substituted; or optionally protected carboxyl; Rb1 is H; cyano halogen; nitre; C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylamino, di(C1-C6 alkyl)amino, acylamino, carbamoyl, sulfamoyl, or a heterocyclic group, each optionally substituted; or optionally protected carboxyl; R2 is aryl or a heterocyclic group, each optionally substituted; R3 is H or a carboxy protecting group; and m is an integer from 0 to 3. |