Visible-light induced generation of bifunctional nitrogen-centered radicals: a concise synthetic strategy to construct bicyclo[3.2.1] octane and azepane cores

A photocatalytic tandem cyclization of o -alkenylbenzaldehydes using pyridinium salts as the amination reagent is described. A variety of valuable seven-membered nitrogenous heterocyclic skeletons are prepared in modest to excellent yields in concise one-step. This transformation features mild reaction conditions and exceptional functional group tolerance. In addition, combining control experiments and density functional theory (DFT) calculations on the mechanism can explain the reaction selectivity.