Three-component and nonclassical reaction of phosphines with enynes and aldehydes: formation of γ-lactones featuring α-phosphorus ylides.

Inverted carbenoid species, generated from attack of phosphines at the α(δ')-carbon of hex-2-en-4-ynedioic acid dialkyl esters, react with aldehydes to give γ-lactones possessing an α-phosphorus ylide moiety.