Expedient Synthesis of Complex γ-Butyrolactones from 5-(1-Arylalkylidene) Meldrum’s Acids via Sequential Conjugate Alkynylation/Ag(I)-Catalyzed Lactonization

The conjugate alkynylation of alkylidene Meldrum’s acids with alkynylalanes and alkynyl Grignards allows for the formation of propargylic all-carbon quaternary stereocenters in high yields. Ag2CO3-catalyzed intramolecular cyclization of propargylic Meldrum’s acid derivatives offers a two-step entry into complex γ-alkylidene butyrolactones containing an all-carbon quaternary center at the C-4 position.