Rhodium-Catalyzed Asymmetric Conjugate Alkynylation of β,γ-Unsaturated α-Ketoesters.

The first example of catalytic asymmetric conjugate alkynylation of β,γ-unsaturated α-ketoesters is reported. By using Rh(I)/(R)-DM-binap complex as the catalyst and diphenyl[(triisopropylsilyl)ethynyl]methanol as the alkynylating reagent, the alkynylation reaction proceeded smoothly to afford α-ketoesters bearing a propargylic chiral center at γ position in good yields with high enantioselectivities.