Direct Zinc(II)-Catalyzed Enantioconvergent Additions of Terminal Alkynes to [alpha]-Keto Esters

The addition of terminal alkynes to racemic [beta]-stereogenic [alpha]-keto esters was achieved in high levels of stereoselectivity, affording versatile tertiary propargylic alcohols containing two stereocenters. This environmentally benign enantioconvergent reaction proceeds with perfect atom economy, requires no solvent, and is catalyzed by a non-toxic zinc salt. The alkyne moiety can be leveraged in downstream transformations including hydrogenation to the corresponding saturated tertiary alcohol, which represents the product of a formal enantioconvergent aliphatic nucleophile addition.