Gold-Catalyzed Regio- and Stereoselective α-Acyloxy-β-Alkynylation of Ynol Ethers

J Org Chem. 2023 Mar 3;88(5):2908-2920. doi: 10.1021/acs.joc.2c02597. Epub 2023 Feb 17.

Abstract

Enol esters and conjugated enynes are valuable structural motifs for synthetic chemistry and material sciences. Herein, the synthesis of tetra-substituted enol ester 2-iodobenzoate derivatives was achieved in good yields at room temperature through a gold-catalyzed acyloxyalkynylation of sensitive ynol ethers with ethynylbenziodoxolones (EBXs), the latter acting as bifunctional reactants. The conversion is highly regioselective with a broad substrate scope. Mechanistically, an Au(III) species is the key intermediate of an Au(I)/Au(III) redox cycle. The reaction is synthetically useful and can easily be scaled up to gram scale.