Cobalt(II) catalysed reaction of alkenes with aliphatic aldehydes and molecular oxygen: scope and mechanism

Abstract

A variety of cobalt(II) complexes can be prepared using Schiff's bases derived from aromatic aldehydes and amines or a-aminoesters. These complexes are versatile catalyst for the reaction between aliphatic aldehydes and various alkenes. The outcome of the reaction is controlled by the electronic nature of the alkene as the electron deficient alkenes undergo oxidative addition of aldehydes followed by dioxygen incorporation to yield 2-hydroxy(acyloxy)-4-oxoesters or nitriles whereas unactivated or electron rich alkenes afford the corresponding epoxides. These reactions are proceeding via a radical pathway and a common acylcobalt intermediate is proposed for the formation of 4 as well as the epoxides 7.