The fine balance between one cross-coupling and two β-hydride elimination pathways: a DFT mechanistic study of Ni(π-allyl)2-catalyzed cross-coupling of alkyl halides and alkyl Grignard reagents

Abstract

The model cross-coupling of EtBr with EtMgCl mediated by Ni(π-allyl)₂ proceeds by a catalytic cycle commencing with transmetalation establishing a novel Mg–allyl interaction, followed by Mg-assisted oxidative addition (the rate-determining step), followed by reductive elimination having much lower barrier than 2 competing β-hydride elimination pathways, and completed by departure of MgBrCl.