Stereoselective synthesis of alkyl-, aryl-, vinyl- and alkynyl-substituted Z-enamides and enol ethers

Chem Sci. 2019 Feb 4;10(11):3223-3230. doi: 10.1039/c8sc05573d. eCollection 2019 Mar 21.

Abstract

Enamides and enol ethers are valuable building blocks in synthetic chemistry, yet their stereoselective synthesis can be challenging. Herein, we report a new stereoselective synthesis of vinyl, aryl, alkynyl, alkyl and thio-substituted Z-enamides and enol ethers based on the use of vinylbenziodoxolone (VBX) reagents. The stable VBX reagents were synthesized by stereoselective addition of N- or O-nucleophiles on the corresponding alkynyl reagents in the presence of a catalytic amount of cesium carbonate. The VBX reagents were used in palladium-catalyzed cross-couplings at room temperature to access Z-enamides and enol ethers.