tert-Butyl (4-(methoxy(methyl)carbamoyl)thiazol-2-yl)carbamate → tert-Butyl (4-propionylthiazol-2-yl)carbamate

Participants

Reaction Conditions

Reaction Steps

A solution of ethyl magnesium chloride (126 mL, 0.252 mol, 2 M in tetrahydrofuran) was stirred and cooled to −70° C. on a dry ice/acetone bath. A solution of [4-(methoxy-methyl-carbamoyl)-thiazol-2-yl]-carbamic acid tert-butyl ester (14.5 g, 0.0504 mol) in tetrahydrofuran (200 mL) was added dropwise over approximately 5 minutes. The mixture was stirred for 1 hour. The cooling bath was removed and stirring continued for an additional 2 hours. The mixture was poured into a mixture of ice and saturated aqueous ammonium chloride solution and then extracted with ethyl acetate. The organic extracts were combined, washed with brine, dried over magnesium sulfate and evaporated to give an off white solid which was purified by chromatography over a 350 g pad of silica gel eluted with 4:1 ethyl acetate/dichloromethane to afford (4-propionyl-thiazol-2-yl)-carbamic acid tert-butyl ester (7.09 g, 55%) as an off white solid.

Provenance & Evidence