Synthesis of electron-poor O-vinyl ethers from stabilized phosphorus ylides in the presence of dipotassium hydrogen phosphate powder in solvent-free conditions

Protonation of highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by phenols leads to vinyltriphenylphosphonium salts, which undergo Michael addition reaction with a conjugate base to produce corresponding stabilized phosphorus ylides. Dipotassium hydrogen phosphate powder was found to catalyze the conversion of stabilized phosphorus ylides to electron-poor O-vinyl ethers in solvent-free conditions under microwave (0.6 KW, 3 min) and thermal (100 degrees C, 60 min) conditions. Relative population of E and Z isomers of electron-poor O-vinyl ethers was determined via their (1)H NMR spectra.