The phase-transfer-catalyzed alkylation of a-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.Keywords: acetylenes; alkylation; asymmetric synthesis; enynes; phase-transfer catalysis Construction of the asymmetric all-carbon quaternary center has widely attracted the attention of synthetic community as it could only be achieved by relying on the use of an enantioselective C À C bond-forming process.[1] Among the variety of protocols developed to date, phase-transfer-catalyzed asymmetric functionalization has been increasingly accepted as one promising tool for this purpose. [2] In this context, we recently introduced the phase-transfer-catalyzed enantioselective alkylation of a-alkynyl esters [Scheme 1, Eq. (1)] as a novel means to generate an asymmetric allcarbon quaternary center bearing an acetylene moiety which is hardly accessible by other means.