A new and efficient route to 4-carboxymethylcoumarins mediated by vinyltriphenylphosphonium salt

Article abstract of DOI:10.1016/S0040-4039(98)00206-8

Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by substituted phenols leads to a vinyltriphenylphosphonium salt, which undergoes aromatic electrophilic substitution reaction with the phenolate conjugate base to produce 4-carboxymethylcoumarins in fairly high yields.