Efficient synthesis of gamma-keto esters through neighboring carbonyl group-assisted regioselective hydration of 3-alkynoates.

The Au(III)-catalyzed hydration of 3-alkynoates led to a practical one-step synthesis of gamma-keto esters in high yields, through a carbonyl group participation enabled by a favored 5-endodig cyclization. This mild-aqueous ethanol, room temperature, and atom-economical method has been used effectively with a wide range of substrates. Using the same conditions, a 2-alkynoate produced the corresponding beta-keto ester in high yield.