Reductive homocondensation of benzylidene- and alkylidenepyruvate esters by a P(NMe2)3-mediated tandem reaction.

A reductive homocondensation of E-benzylidenepyruvate esters mediated by P(NMe2)3 is described. The transformation, initiated by the Kukhtin-Ramirez addition of the phosphorus reagent to the vinyl-substituted α-dicarbonyl substrate, proceeds via a resonance delocalized oxyphosphonium dienolate intermediate to provide access to diverse oxygenated heterocycles as a function of the substituent.