Highly Efficient and Stereoselective Radical Addition of Tertiary Amines to Electron-Deficient Alkenes − Application to the Enantioselective Synthesis of Necine Bases

Abstract

A convenient and highly efficient method for the regio- and stereoselective addition of tertiary amines to electron-deficient alkenes has been elaborated. It is based on a radical chain reaction of α-aminyl radicals with alkenes, induced by a photoelectron transfer process between tertiary amines 2a−j and excited electron donor substituted phenyl ketones. The influence of the nature of the amino substituents and of the alkene on the reaction have been examined. In the presence of (5R)-5-menthyloxy-2-(5H)-furanone (1) as electron-deficient alkene, the addition of N-alkylpyrrolidines 2a−e occurred with a complete facial selectivity and up to 94% isolated yields. This method has been applied to a fast, efficient and enantioselective synthesis of necine bases.