Synthesis and Reaction of Triphenylvinylphosphonium Salts from Epoxides

Triphenylvinylphosphonium salts were prepared by the reaction of 2-hydroxyalkyltriphenylphosphonium salts with acetyl chloride or oxalyl chloride. These salts were also synthesized by a one-pot operation of treating epoxides with triphenylphosphonium tetrafluoroborate, followed by the addition of acetyl chloride or oxalyl chloride successively. The reaction of these salts with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and aromatic aldehydes afforded the corresponding dienes in moderate yields via α,β-unsaturated ylide intermediates.