Photocatalytic synthesis of sulfonamidylated chroman-4-ones: metal- and oxidant-free radical addition-cyclization.

A metal- and oxidant-free photocatalytic cascade reaction has been developed for the divergent synthesis of sulfonamidylated chroman-4-ones. This visible-light-driven protocol employs readily available o-(allyloxy)arylaldehydes and N-sulfonylaminopyridinium salts as feedstocks. A sulfonamidyl radical-triggered addition-cyclization sequence enables the one-step assembly of a new heterocyclic ring with the concomitant formation of C-N and C-C bonds. The mild conditions afford the desired products in moderate to good yields, obviating the need for noble-metal catalysts or external oxidants. This sustainable strategy not only enriches the structural diversity of chroman-4-one scaffolds but also paves the way for constructing bioactive compound libraries.