Highly enantioselective alkynylation of α-keto ester:: An efficient method for constructing a chiral tertiary carbon center

[GRAPHICS] The asymmetric addition of terminal alkynes to a-keto ester was carried out using a catalytic amount of (11 S,2S)-3-(tert-butyldimethylsilyloxyl)2-N,N-(dimethylamino)-l-(p-nitrophenyl)-propane-1-ol in the presence of Zn(OTf)(2) to give the corresponding tertiary propargylic alcohols in high yields with up to 94% ee. N-Methylephedrine and Zn(OSO2CHF2)(2) were also examined in this reaction.