Bronsted Acid Catalyzed Oxygenative Bimolecular Friedel-Crafts-type Coupling of Ynamides

A non-metal approach for accessing alpha-oxo carbene surrogates for a C-C bond-forming bimolecular coupling between ynamides and nucleophilic arenes was developed. This acid-catalyzed coupling features mild temperature, which is critical for the required temporal chemoselectivity among nucleophiles. The scope of nucleophiles includes indoles, pyrroles, anilines, phenols and silyl enolethers. Furthermore, a direct test of S(N)2' mechanism has been provided by employing chiral N,N'-dioxides which also enlightens the nature of the intermediates in related metal-catalyzed processes.