Metal-Free, Visible-Light-Promoted Synthesis of 3-Phosphorylated Coumarins via Radical C-P/C-C Bond Formation

A metal-free, visible-light-promoted direct difunctionalization of alkynoates was achieved under mild conditions. By employing catalytic quantities of the commercially available Eosin Y (EY) as the photocatalyst and tert-butyl-hydroperoxide (TBHP) as the oxidant, we developed a radical tandem phosphorylation/cyclization reaction to synthesize various 3-phosphorylated coumarins with high functional group tolerance, moderate to good yields, and excellent regioselectivities.