Visible-Light-Initiated Na₂‑Eosin Y Catalyzed Highly Regio- and Stereoselective Difunctionalization of Alkynes with Alkyl Bromides

A highly regioselective and stereoselective addition of alkyl bromides (amino-brominated aromatic β,β-dicyanoalkenes) to arylacetylenes by photoredox catalysis was developed. This difunctionalization of arylacetylenes was accomplished under ambient and metal-free conditions to produce alkenyl bromides in high efficiency with a wide range of group tolerance.