Photoredox-Catalyzed Metal-Free Regio- & Stereoselective C(sp²)–H Amination of Enamides with N-Aminopyridium Salts

A visible-light-induced photoredox-catalyzed regioselective and stereoselective C(sp²)–H amination of enamides with bench-stable and easily accessible N-aminopyridium salts is developed, affording synthetically and biologically prominent vicinal 1,2-diamine scaffolds with broad substrate scope and excellent functional group compatibility. The transformation proceeded through a radical pathway involving the Giese addition of the relatively electrophilic N-centered sulfonamidyl radical species to nucleophilic β-olefinic position of enamides followed by the ensuing single electron oxidation and β-H elimination, delivering geometrically-defined Z-configured β-sulfonamidylated enamides. The operational simplicity, environmental friendliness and cost efficiency of this methodology allowed it to pave a new avenue to enrich the arsenal of synthetically crucial functionalized enamides and their related derivatives.