Fe-catalysed Kumada-type alkyl–alkyl cross-coupling. Evidence for the intermediacy of Fe(i) complexes

Abstract

A novel Fe–NHC catalytic system allows the alkyl–alkyl cross-coupling reaction of alkyl halides and alkylmagnesium reagents has been developed. To our knowledge, this is the first Fe-catalysed Kumada-type coupling for the formation of C(sp3)–C(sp3) bonds in the presence of functional groups. The process takes place under mild conditions, avoiding the formation of β-elimination products. Mechanistic studies suggest the intermediacy of Fe(I) complexes, formed by reduction with the Grignard reagent, as the active species.