Gold(I)/Chiral N,N′-Dioxide-Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement

A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a pi-acidic gold(I) complex witha Claisen rearrangement catalyzed by a chiral Lewis acidic N,N'-dioxide-nickel(II) complex. A range of acyclic alpha-allyl beta-keto esters were synthesized in high yields (up to 99%) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99% ee) under mild reaction conditions. These products can be easily transformed into optically active beta-hydroxy esters, beta-hydroxy acids, or 1,3-diols.