Ligand-controlled cobalt-catalyzed isomerization and reductive C–O bond cleavage of allylic ethers

Abstract

Reported herein are the ligand-controlled cobalt-catalyzed isomerization and reductive C–O bond cleavage of allylic ethers. With an amido-diphosphine ligand (PNP), the isomerization occurred smoothly, producing a series of trisubstituted enol ethers with high stereoselectivity. Using a phosphine-amido-oxazoline ligand (PAO), the reaction switched to reductive C–O bond cleavage in the presence of HBpin. Preliminary mechanistic studies suggested that both reactions occurred via a cobalt-hydride mediated alkene insertion to form an alkylcobalt species, from which selective β-elimination was controlled by the ligand.