Green-LED (Auto)Photocatalysis Initiated by a Transient Charge-Transfer Complex of N-Bromoacetamide and Mes-Acr-MeClO4

Mes-Acr-MeClO4, a well-known blue-LED visible light photocatalyst, formed a dark red charge-transfer (CT) complex with N-bromoacetamide (NBA) in the presence of K2CO3. This complex enabled the absorption of green light, leading to the generation of an N-centered radical from N-bromoacetamide. This radical underwent anti-Markovnikov and anti-periplanar addition to phenylacetylene, resulting in 100% Z-selective (Z)-N-(2-bromo-2-phenylvinyl)acetamide. The (Z)-N-(2-bromo-2-phenylvinyl)acetamide (λem ~ 518 nm, τ ~ 10 ns) proved to be an effective green and red-LED (auto)photocatalyst, facilitating the synthesis of (Z)-N-(2-bromo-2-phenylvinyl)acetamide from phenylacetylene and NBA within the same reaction system. The process was found to be 100% atom-economical.