Triethylamine → (3S)-3-[2-(tert-Butyldimethylsilyloxy)ethyl]-5-oxo-1-[(1R)-1-phenylethyl]pyrrolidine-3-carboxylic acid tert-butyl ester

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Reaction Steps

Triethylamine (3.0 mL, 21.8 mmol) was added to a solution of (3S)-3-(2-hydroxyethyl)-5-oxo-1-[(1R)-1-phenylethyl]pyrrolidine-3-carboxylic acid tert-butyl ester (2.42 g, 7.25 mmol) in dichloromethane (70 mL), and the mixture was cooled to 0° C. tert-Butyldimethylsilyl trifluoromethanesulfonate (2.50 mL, 10.9 mmol) was added dropwise, and the mixture was stirred at the same temperature for 1.5 hours. After addition of an ice piece and stirring, the reaction solution was poured into a mixture of ethyl acetate (50 mL) and saturated sodium bicarbonate (50 mL), followed by extraction with ethyl acetate (200 mL, 100 mL). The organic layers were combined and washed with brine (50 mL). After drying over anhydrous sodium sulfate and filtration, the solvent was concentrated under reduced pressure. The resulting residue was purified by silica gel chromatography (hexane:ethyl acetate=4:1→2:1) to give 2.84 g (88%) of the title compound as a white solid.

Provenance & Evidence