Benzyl chloroformate → 4-[(R)-2-(tert-Butyldimethylsilyloxy)-1-(methyl)ethyl]pyrrolidine-1,3-dicarboxylic acid 1-benzyl ester 3-methyl ester

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Reaction Steps

Benzyloxycarbonyl chloride (10.2 mL, 71.5 mmol) was added to a solution of 1-benzyl-4-[(R)-2-(tert-butyldimethylsilyloxy)-1-(methyl)ethyl]pyrrolidine-3-carboxylic acid methyl ester (14.0 g, 35.8 mmol) in dichloromethane (200 mL), and the mixture was stirred for one hour. Saturated sodium bicarbonate water was added to the reaction mixture. The organic layer was separated, dried over magnesium sulfate, and filtered. Then, the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=4:1) to give 13.9 g (89%) of the diastereomer mixture title compound as a colorless oil. The diastereomers were used for the next step without separation.

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