Enantioselective Synthesis of (<i>R</i>)- and (<i>S</i>)-Cizolirtine; Application of Oxazaborolidine-Catalyzed Asymmetric Borane Reduction to Azolyl Phenyl Ketones

Abstract

An efficient enantioselective synthesis of (R)- and (S)-cizolirtine 1 is described. The key step of the procedure is the CBS-oxazaborolidine asymmetric reduction of phenyl pyrazolyl ketone 2. Related enantioselective reductions of several azolyl phenyl ketones are also reported.