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

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 beta-elimination was controlled by the ligand.

Automated summary

The ligand-controlled cobalt-catalyzed isomerization and reductive C-O bond cleavage of allylic ethers are reported in this paper. With an amido-diphosphine ligand (PNP), the isomerization reaction proceeds smoothly, resulting in a series of trisubstituted enol ethers with high stereoselectivity. By using a phosphine-amido-oxazoline ligand (PAO), the reaction switches to reductive C-O bond cleavage in the presence of HBpin. Preliminary mechanistic studies suggest that both reactions proceed through cobalt-hydride mediated alkene insertion to form an alkylcobalt species, which is then selectively eliminated by the ligand.