L-Hydroxyproline → 1-(4-Toluenesulfonyl)-4-hydroxy-D-proline

Participants

Reaction Conditions

Reaction Steps

A stirred solution of 52.45 g (0.40 mole) of trans-4-hydroxy-L-proline in 500 ml of sodium hydroxide is treated with 85.79 g (0.45 mole) of p-toluenesulfonyl chloride in 500 ml of ether at room temperature. Stirring is continued for 6 hours, the layers are separated and the aqueous phase is cooled to 5° C. in an ice-bath. The mixture is then acidified while cooling with 30 ml of concentrated hydrochloric acid to pH 2 and the precipitated white solid is collected, washed with 150 ml of cold water, and dried in vacuo yielding 106.2 g of material, melting point 139°-143° C. Crystallization from 300 ml of ethyl acetate yields 98.6 g of the title compound, melting point 142°-145° C.

Provenance & Evidence