Ketoprofen → (S)-(-)-Ketoprofen cinchonidine

Participants

Reaction Conditions

Reaction Steps

Cinchonidine (155 g; 0.53 mol) was added to a solution of 115g (0.59 mol) of racemic ketoprofen and 2.8 L of ethyl acetate under vigorous stirring at 50°-60° C. The mixture was diluted with 280 mL of methanol, cooled to 35° C., then seeded with 98% enantiomerically pure S-salt to induce crystallization. After stirring at room temperature for 16 h and 0° C. for 5-6 h, the precipitated diastereomeric salt was filtered under vacuum, washed three times with ethyl acetate and three times with ether, and then dried under vacuum for 16 h [Yield: 127 g (or 44%); enantiomeric purity: 86% S]. One recrystallization from 1.7 L of ethyl acetate/methanol (10:1) afforded 88 g (31% yield) salt of 97% enantiomerically pure S-ketoprofen.

Provenance & Evidence