Gold-Catalyzed Selective Synthesis of N-Sulfonyl Enaminone Isomers from Sulfonamides and Ynones

Abstract

Au-catalyzed chemoselective methods for synthesizing N-sulfonyl enaminones are developed. Two different isomers are obtained in a chemocontrolled manner by employing the different properties of Au(I) and Au(III) catalysts. Hydroamidation and proton-assisted carbonyl activation followed by Meyer−Schuster rearrangement are proposed as the working mechanisms for each isomer of the reactions. A wide range of substrates afforded moderate to excellent yields and selectivities. These reactions represent the first examples of transition-metal-catalyzed enamine synthesis from sulfonamides and alkynes.