Abstract

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates (or alkyl acetylenecarboxylates), by 1,2,3,6-tetrahydrophthalimide leads to vinyltriphenylphosphonium salts, which undergo Michael addition reaction with conjugate base to produce phosphorus ylides. Dipotassium hydrogen phosphate and silica gel were found to catalyze conversion of the phosphorus ylides to electron-poor N-vinyl imides in solvent-free conditions under thermal (80–90°C, 40–50 min) conditions. The structural analysis of the products indicated that the reaction is regio- and stereoselective.