The title compound 2-(1-(benzo[d]thiazol-2-ylcarbamoyl)indolin-6-yl)thiazole-4-carboxylic acid (28) was prepared by the following procedure: A mixture of ethyl 2-(1-(benzo[d]thiazol-2-ylcarbamoyl)indolin-6-yl)thiazole-4-carboxylate (28E) (22 mg, 0.05 mmol) and LiOH (12 mg, 0.49 mmol) was stirred in MeOH (2 mL) and water (1 mL) for 20 h. The mixture was diluted with EtOAc (5 mL) and acidified with 1M HCl. The organic layer was isolated, washed with H2O, dried over MgSO4, filtered and concentrated under reduced pressure. The crude material was purified by HPLC, to provide 3.0 mg (14%) of the desired product 2-(1-(benzo[d]thiazol-2-ylcarbamoyl)indolin-6-yl)thiazole-4-carboxylic acid (28). LC/MS (APCI): m/z 423.1 (M+H), 844.8 (2M+1).
