Abstract

Protonation of the highly reactive 1:1 intermediates produced in the reaction between tributylphosphine and dialkyl acetylenedicarboxylates by imides (phthalimide and succinimide) leads to vinyltributylphosphonium salts, which undergo an addition-elimination reaction in CH 2Cl2 at room temperature to produce the corresponding N -vinylimides ( Z isomers) in excellent yields