Carbenylative Amination and Alkylation of Vinyl Iodides via Palladium Alkylidene Intermediates

Abstract

Most palladium-catalyzed reactions involving insertion of alkylidenes with α-hydrogens undergo β-hydride elimination from alkylpalladium(II) intermediates to form alkenes. Vinyl iodides were shown to generate η(3)-allylpalladium intermediates that resist β-hydride elimination, preserving the sp(3) center adjacent to the carbene moiety. Acyclic stereocontrol (syn/anti) for carbenylative amination and alkylation reactions was low, suggesting a lack of control in the migratory insertion step. Highly hindered carbene precursors inexplicably led to formation of Z-alkenes with high levels of stereocontrol.