Benzoyl Peroxide → 4-Bromomethyl-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic Acid Ethyl Ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 200 g of commercially available 4-methyl-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic acid ethyl ester in 1.6 L of dichloromethane were added 20.5 g of benzoyl peroxide and 124 g of NBS. The resulting mixture was refluxed in the dark for 22 h. After cooling to 0° C., the mixture was filtered. The filtrate was concentrated to half volume under reduced pressure, washed with water, dried over magnesium sulfate, filtered and concentrated under reduced pressure to give a white solid. The solid was recrystallized in 900 mL of diisopropyl ether 80/dichloromethane 20 to give a first crop of 101 g of 4-bromomethyl-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic acid ethyl ester. The filtrate was concentrated under reduced pressure then recrystallized in 300 mL of diisopropyl ether 90/dichloromethane 10 to give a second crop of 72 g. A total of 173 g of 4-bromomethyl-2-(4-trifluoromethyl-phenyl)-thiazole-5-carboxylic acid ethyl ester was obtained as a white solid. 4 WO02067912

Provenance & Evidence