Dipotassium Hydrogen Phosphate Catalyzed Synthesis of New Aryle Vinyl Ethers from 2-Hydroxybenzaldehyde Derivatives, Acetylenic Esters and Tributylphosphine

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between tributylphosphine and alkyl acetylenecarboxylates by 2-hydroxybenzaldehyde derivatives leads to vinyltributylphosphonium salts, which undergo Michael addition reaction with conjugate base to produce corresponding phosphorus ylides. Dipotassium hydrogen phosphate powder was found to catalyze the conversion of phosphorus ylides to new electron poor (E, Z) aryl vinyl ethers in solvent free conditions under microwave (0.5 KW, 3 min) and thermal (90◦C, 60 min) conditions.