ChemInform Abstract: Development of a Robust Reagent for the Two‐Carbon Homologation of Aldehydes to (E)‐α,β‐Unsaturated Aldehydes in Water.

Abstract The new pinacolacetalphosphonium salt (V) smoothly reacts with aldehydes in aqueous medium to give homologated acetals which hydrolyze to corresponding two‐carbon homologated unsaturated aldehydes with excellent (E)‐selectivity.