On direct iron-catalyzed cross-coupling reactions

A new methodology for the direct cross-coupling reaction between aryl halides and alkyl halides under iron catalysis is described. Unlike conventional protocols, the direct cross-coupling obviates the need for the preformation of stoichiometric amounts of Grignard species and thus exhibits a reduced hazard potential. The underlying one-pot reaction involves iron-catalyzed Grignard formation followed by a rapid cross-coupling step. Mechanistic data on the role of N,N,N',N'-tetramethylethylenediamine (TMEDA) as additive, the concentration of intermediates, and the nature of the catalyst species are discussed.