Electrochemical oxidative monofluoromethylation of N-acryl-2-aryl benzimidazoles: access to CFH2-containing benzimidazo[2,1-a]isoquinolin-6(5H)-one derivatives

An efficient monofluoromethylation of N-acryl-2-aryl benzimidazoles was developed through an electro-oxidative CFH₂-radical generation, followed by cascade cyclization fabricating a benzimidazo[2,1-a]isoquinolin-6(5H)-one scaffold. The protocol used the readily available CFH₂SO₂Na as the monofluoromethylation reagent, enabling the step economical synthesis of polycyclic benzimidazoles in moderate to high yields under metal- and oxidant-free conditions. Furthermore, the reaction mechanism was subjected to investigation, and it was demonstrated that the necessity of anodic oxidation in the cascade process.