ChemInform Abstract: Chiral N,N-Dialkylnorephedrines as Catalysts of the Highly Enantioselective Addition of Dialkylzincs to Aliphatic and Aromatic Aldehydes. The Asymmetric Synthesis of Secondary Aliphatic and Aromatic Alcohols of High Optical Purity.

Abstract

The chiral N,N-dialkylnorephedrine-catalyzed addition of dialkylzincs to aliphatic and aromatic aldehydes afforded secondary alcohols of high optical purity (to >95% ee). Among the N,N-di(primary alkyl) norephedrines, N,N-di-n-butylnorephedrine (DBNE, 3d) was found to be the most effective catalyst. 1-Phenyl-2-(1-pyrrolidinyl) propan-1-ol (3i) and N,N-diallylnorephedrine (3j) were also highly effective catalysts. The method described provides optically active secondary aliphatic alcohols of high optical purity which cannot be prepared by conventional methods