Trifluoroacetic acid → 2-((S)-2-amino-3-phenyl-propionylamino)-thiazole-4-carboxylic acid methyl ester

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Reaction Steps

2-((S)-2-tert-Butoxycarbonylamino-3-phenyl-propionylamino)-thiazole-4-carboxylic acid methyl ester (2.4 g, 5.919 mmol) was mixed in dichloromethane (25 mL) in an ice-bath. Trifluoroacetic acid (18 mL, 235 mmol) was added and the solution was stirred for 1.5 hours. The reaction mixture was evaporated and the residue was triturated with ether. The suspension was stirred vigorously for 10 minutes and then filtered. The solid was partitioned between aqueous sodium bicarbonate and dichloromethane. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The combined organic extracts were washed with brine and dried over sodium sulfate. Evaporation of the solvents gave 2-((S)-2-amino-3-phenyl-propionylamino)-thiazole-4-carboxylic acid methyl ester as an off white solid (1.58 g, 87%).

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