Development of a robust reagent for the two-carbon homologation of aldehydes to ( E )-α,β-unsaturated aldehydes in water

Synthesis of a new pinacolacetal-phosphonium salt and its reaction with aldehydes to give homologated acetals and two-carbon homologated unsaturated aldehydes is presented. The chemistry takes place in water under mild conditions and the sequence can be performed in one-flask operation.