反应详情

A solution of INTERMEDIATE B (1.325 g, 3.70 mmol) in DCM (7.40 mL) was cooled to 0° C. in an ice-water bath, and chlorosulfonic acid (1.230 mL, 18.50 mmol) was added dropwise. The resulting solution was stirred at RT for 4 hours until complete conversion to the desired product occurred. The reaction mixture was then slowly added dropwise to well-stirred ice water and subsequently neutralized to a pH of about 7 with saturated aqueous sodium bicarbonate solution. After extraction with EtOAc (×3), the combined organics were washed with water and brine, dried over magnesium sulfate, filtered and concentrated to provide INTERMEDIATE C. The material was taken forward without further purification. m/z (ESI) 477.8 (M+Na)+.