Visible-light photoredox catalysis: aza-Henry reactions via C-H functionalization.

We report the application of visible-light photoredox catalysis for the formation of C-C bonds between tertiary N-arylamines and nitroalkanes via an oxidative aza-Henry reaction. In the presence of 1 mol % Ir(ppy)(2)(dtbbpy)PF(6), efficient coupling of nitroalkanes with in situ-generated iminium ions provides the desired products in up to 96% yield. Mechanistic studies suggest that reductive quenching of the Ir(3+) excited state by the tertiary amine leads to the ammonium radical cation, with subsequent catalyst turnover (Ir(2+) --> Ir(3+)) likely effected by atmospheric oxygen.