Catalytic Asymmetric Epoxidation and Aziridination Mediated by Sulfur Ylides. Evolution of a Project

Abstract

A novel, catalytic and asymmetric process for carbonyl epoxidation and imine aziridination has been developed. The processes utilise diazo compounds and the reactions are mediated by catalytic quantities of transition metals (rhodium acetate or copper acetylacetonate) and sulfides. In this catalytic cycle, the diazo compound is decomposed by the metal to give metal carbenoid which reacts with the sulfide to give a sulfur ylide. This in turn reacts with the aldehyde to give an epoxide and returns the sulfide back into the catalytic cycle. Substitution of the aldehyde for an imine furnishes aziridines in high yield. Both expoxidation and aziridination can be rendered asymmetric by the use of chiral sulfides in the catalytic process. This account describes how these processes evolved.