Phase-Transfer-Catalyzed Olefin Isomerization/Alpha-Alkylation Of Alpha-Alkynylcrotonates As A Route For 1,4-Enynes

The phase-transfer-catalyzed alkylation of alpha-alkynylcrotonates was developed as a means to provide 1,4-enynes deconjugated by an all-carbon quaternary center. Extension to the asymmetric version using the chiral phase-transfer catalyst (S)-3 provided the alkylated compounds with up to 87% ee.