4-Toluenesulfonyl chloride → Ethyl 3-[3,4-difluoro-5-((1S)-1-hydroxy-2-{[(4-methylphenyl)sulfonyl]oxy}ethyl)phenyl]propanoate

Participants

Reaction Conditions

Reaction Steps

p-Toluenesulfonyl chloride (12.4 g, 64.8 mmol) in pyridine (35 mL) was added dropwise over 7 min to a cooled (−10 to −20° C.) solution of ethyl 3-{3-[(1S)-1,2-dihydroxyethyl]-4,5-difluorophenyl}propanoate (17.7 g, 64.8 mmol) in pyridine (70 mL) under N2. The reaction was stirred at −10 to −20° C. for ˜4.5 h. The reaction was quenched with ice H2O and stirred overnight. The reaction mixture was diluted with H2O and extracted three times with ethyl ether. The combined organic layers were washed with 1N HCl, aq. CuSO4, and brine. The organic layer was dried over MgSO4, filtered, and concentrated. Purification by column chromatography (0-80% ethyl acetate:hexane) afforded the desired product (22.5 g, 81%) along with some recovered starting material (2.13 g).

Provenance & Evidence