D-Proline → (S)-N-isobutoxycarbonylproline

Participants

Reaction Steps

A solution of isobutyl chloroformate (4.4 mL, 34.04 mmol) in acetone is added dropwise to a solution of L- or D-proline (4.0 g, 34.74 mmol) and sodium bicarbonate (10 g, 125 mmol) in water (50 mL). The mixture is stirred overnight. After removal of acetone, the aqueous solution is acidified to pH 2 with hydrochloric acid while maintaining the temperature below 20° C., and then extracted with ethyl acetate (3×25 mL). The combined organic phase is dried over anhydrous magnesium sulfate and evaporated in vacuo to give (S)-N-isobutoxycarbonylproline (from L-proline) or (R)-N-isobutoxycarbonylproline (from D-proline) correspondingly, as colorless oil.

Provenance & Evidence