Photocatalytic Alkene-Migrative Chain Elongation of 2-Phosphinostyrenes with Aldehydes

The photocatalytic alkene-migrative chain elongation reaction of 2-phosphinostyrenes with aldehydes under mild conditions in response to blue light was demonstrated. A broad range of aldehydes, both aliphatic and aromatic, participated in this reaction to afford alkene-phosphine oxides in a Z-selective manner. Mechanistic experiments suggested the formation of benzophospholene-based ylide intermediates via photocatalytic cyclization of phosphinostyrenes followed by solvent-mediated proton transfer under base-free reaction conditions.