Photoredox-Catalyzed Tandem Cyclization of Enaminones with <i>N</i>-Sulfonylaminopyridinium Salts toward the Synthesis of 3-Sulfonaminated Chromones

Abstract

A photoredox-catalyzed intermolecular tandem sulfonamination/cyclization of enaminones was realized by using <i>N</i>-aminopyridinium salts as the sulfonaminated reagents without transition-metal catalysts or bases. The reaction exhibits a broad scope and good functional group tolerance, good yields, and regioselectivity. Preliminary mechanistic studies support the radical property of the reaction and the involvement of <i>N</i>-centered radical intermediates.