Tandem oxidation–Wittig–Wittig sequences for the preparation of functionalised dienoates

A range of functionalised dienes and trienes have been prepared by one-pot processes in which alcohol oxidation is accompanied by in situ Wittig homologation using Trippett’s reagent [(triphenylphosphoranylidene)acetaldehyde] followed by addition of a second stabilised phosphorane. This procedure has been applied to α-hydroxy carbonyl compounds and activated benzylic alcohols.