Visible-Light Photoredox-Catalyzed Difunctionalization of Alkynes with Quinoxalin-2(1 H )-Ones, P 4 S 10 , and Alcohols.

Visible-light photoredox-catalyzed method has been developed for the synthesis of quinoxalin-2(1 H )-one-containing vinyl phosphorodithioates via direct difunctionalization of alkynes with quinoxalin-2(1 H )-ones, P 4 S 10 and alcohols. This four-component reaction could be carried out under metal-free and mild conditions, affording a number of quinoxalin-2(1 H )-one-containing vinyl phosphorodithioates in moderate to good yields with Z-isomers as the major products. Photocatalytic radical mechanism is proposed based on the results of radical trapping and fluorescence quenching experiments.