Vinyl Triphenylphosphonium Salt–Mediated Synthesis of Functionalized Alkenes

Abstract

Deoxybenzoin undergoes a smooth reaction with acetylenic esters in the presence of triphenylphosphine to produce phosphorus ylides. Only the tert-butyl phosphorus ylide undergoes an intramolecular Wittig reaction to produce highly strained cyclobutenes in boiling toluene, which spontaneously undergoes ring-opening reactions to produce highly functionalized 1,3-dienes. The unstable ylides undergo a 1,2-proton transfer and the loss of PPh₃ to produce functionalized alkenes.

Keywords:

• Alkyl propiolates
• deoxybenzoin
• dialkyl acetylenedicarboxylate
• triphenylphosphine
• Wittig reaction