Palladium-Catalyzed Selective Alkylation of 2-Alkynyl Allyl Ethers with Hydrazones via HOME-Chemistry.

A palladium-catalyzed cross-coupling of 2-alkynyl allyl ethers with hydrazones, which are generated in situ from a variety of aryl and alkyl aldehydes and hydrazine, was developed for the synthesis of valuable enynes featuring a tetrasubstituted carbon center. This approach relied on carbonyl umpolung to act as alkyl carbanion equivalents for selective C(sp3)-C(sp3) bond formation through the elimination of stoichiometric metal catalysts and organic halides/pseudohalides as electrophiles. Notably, alkynyl and alkenyl moieties were intact under the mild reaction conditions. The methodology also features a broad substrate scope, good functional group tolerance, and further product derivatization.