Ynamide-Mediated Thionoester and Dithioester Syntheses

A novel ynamide-mediated synthesis of thionoesters and dithioesters is described. The selective addition reactions of various monothiocarboxylic acids with ynamide furnish alpha-thioacyloxyenamides, which undergo transesterification with nucleophilic -OH or -SH species to afford thionoesters and dithioesters, respectively. The broad substrate scope, mild reaction conditions, and excellent yields make this method an attractive synthetic approach to thionoesters and dithioesters.