A One Pot, Facile, and Convenient Synthesis of Some Coumarin Derivatives

Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by substituted phenols lead to vinyl triphenylphosphonium salt, which undergoes aromatic electrophilic substitution reaction with the phenolate conjugated base to produce coumarin derivatives.