A novel deoxygenation–isomerization reaction of 4-hydroxy-2-ynoic esters and γ-hydroxy-α,β-ynones

(2E, 4E)-Dienoic esters and (E,E)-α,β:γ,δ-dienones have been stereoselectively synthesized from 4-hydroxy-2-ynoic esters and γ-hydroxy-α,β-ynones by their reactions with triphenylphosphine under mild conditions.