Hydrochloric Acid → 2-(2-Amino-5-benzyloxy-phenylamino)-4-(3-chloro-phenyl)-thiazole-5-carboxylic acid ethyl ester

To a mixture of 5.09 g (10 mmole) of 2-(5-benzyloxy-2-nitro-phenylamino)-4-(3-chloro-phenyl)-thiazole-5-carboxylic acid ethyl ester (VI.25), 100 mL of tetrahydrofuran and 20 mL of 1M hydrochloric acid, was added portionwise, 10 g of zinc powder. The mixture was stirred at ambient temperature for 2 hours. The solid was removed by filtration, the filtrate was concentrated under reduced pressure and 200 mL of water was added to the residue. The pH was adjusted to 9 by addition of 15% sodium hydroxide. The precipitate was collected by filtration to give crude 2-(2-amino-5-benzyloxy-phenylamino)-4-(3-chloro-phenyl)-thiazole-5-carboxylic acid ethyl ester (VII.25). This material was carried through to next reaction without further purification.