Visible-Light-Promoted Dual C-C Bond Formations of Alkynoates via a Domino Radical Addition/Cyclization Reaction: A Synthesis of Coumarins.

A visible-light-promoted, mild, and direct difunctionalization of alkynoates has been accomplished. This procedure provides a new strategy toward synthesis of the coumarin core structure by photoredox-mediated oxidation to generate the α-oxo radical, which supervenes a domino radical addition/cyclization reaction in moderate to good yields with high regioselectivity at ambient temperature. [ABSTRACT FROM AUTHOR]