Visible-Light-Induced Reductive Coupling of Arylacetylenes with Benzothiazole Sulfones.

In this study, we propose heavy-metal-free reductive coupling of arylacetylenes with benzothiazole sulfones. The reactions of alkyl or benzylic benzothiazole sulfones with arylacetylenes are successfully performed in the presence of Hantzsch esters and K 2 CO 3 under visible-light irradiation to afford 1,2-disubstituted alkenes in moderate to good yields, with Z -isomer as the major product. The utility of this protocol is expanded to α-deuterative coupling using a deuterated Hantzsch ester, furnishing the corresponding alkenes with high deuterium incorporation.