Abstract

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by phenols (1-hydroxynaphthalene, 2-hydroxynaphthalene, and 4-bromophenol) leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce corresponding stabilized phosphorus ylides. Manganese(II) sulfate powder was found to catalyze conversion of the stabilized phosphorus ylides to coumarins in solvent-free conditions at 90°C due 1 h in high conversions. Microwave also was found to catalyze the same reactions in the presence of manganese(II) sulfate powder in solvent-free conditions at microwave power 1 KW in 1 min.