Photo-induced decarboxylative radical cascade cyclization of unactivated alkenes: access to CF- and CF2-substituted ring-fused imidazoles†

A mild and effective visible-light-induced decarboxylative radical cascade reaction of olefin-containing imidazoles with α-fluorinated carboxylic acids as building blocks containing CF or ArCF₂ moieties, has been developed to afford a series of monofluoromethylated or aryldifluoromethylated polycyclic imidazoles in medium to excellent yields with features of simple operation, available raw materials, and wide substrate scopes. In addition, the mechanistic experiments indicated that the methodology involved a radical pathway.