Stereoselective Conjugate Addition of the Lithium Anion of N-Allyl Imine to Unsaturated Esters: Application to the Enantiospecific Total Synthesis of (-)-Epibatidine

Abstract

A regio- and diastereoselective conjugate addition of the lithium anion of N-allyl imine (prepared from allylamine and benzophenone) to α,β-unsaturated esters in good yields is reported. The reaction was general and provided the γ-amino esters resulting from the regioselective C-C bond formation between the α-carbon to the nitrogen in the imine and the β-carbon of the unsaturated ester. Synthetic utility of the formed products was illustrated in the nonracemic total synthesis of the bioactive alkaloid (-)-epibatidine.