Sodium benzoate as a mild base catalyst for the tandem Michael-aldol self-condensation of gamma,delta-unsaturated beta-ketoesters

An efficient procedure has been developed for the tandem Michael-aldol self-condensation of δ,γ-unsaturated β-ketoesters (1), using sodium benzoate as a mild base catalyst to furnish conjugated vinylcyclohexenonedicarboxylates (2) some of which show biological activity against ectoparasites in cattle.