Kinetic resolution of a diltiazem intermediate by lipase-catalyzed enantioselective alcoholysis

A novel enzymatic resolution of an important alcohol intermediate in the Diltiazem process was developed. The enzymatic reaction involved alcoholysis of the alcohol acetate with butanol, thus obtaining the (R,R)-alcohol and the remaining (S,S)-acetoxy-alcohol in >95% enantiomeric excess. This resolution may serve as the key step in a possible recycling procedure for the waste streams of the Diltiazem process, which will allow a significant increase in the overall process yield.