4-Toluenesulfonyl chloride → N-tert-Butoxycarbonyl-cis-4-(p-Toluenesulfonyloxy)-D-Proline Methyl Ester

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Reaction Steps

4-Dimethylaminopyridine (1.21 g) and p-toluenesulfonyl chloride (1.51 g) were added to a solution of N-tert-butoxycarbonyl-cis-4-hydroxy-D-proline methyl ester (A, 971 mg) in dichloromethane (20 mL). After stirrng at room temperature for 4 hr, the solvent was removed in vacuo. The residue was diluted with ethyl acetate, and washed with 10% citric acid, water, and brine. The organic layer was dried over anhydrous sodium sulfate and evaporated in vacuo. The residue was purified by silica gel column chromatography (chloroform then chloroform:ethyl acetate=1:50, v/v) to give the title compound (1.65 g) as a colorless oil.

Provenance & Evidence