Sunlight induced C-H arylation of aromatic heterocycles: First example of A3 and A2B type corroles as photoredox catalysts

Abstract

The visible light mediated metal-free approach has been developed for C–H arylation and borylation employing anilines as starting material. A series of meso-aryl corroles (A3 and A2B type) were synthesized and their catalytic potential was tested in blue light and sunlight. The method includes substituted anilines as source of expensive aryl diazonium salts and utilizes only 0.5 to 1 mol% of corrole catalyst at room temperature. Corrole catalyst worked efficiently under the blue light/sunlight to produce heterobiaryls and aryl boronic esters in decent to good yields (15–80 %). Mechanistic insight was obtained from TD-DFT studies, which suggested single electron transfer (SET) from the singlet state of corrole catalyst to the aryl diazonium salt. The paper demonstrates corrole based photo-redox catalysis as a mild, green and eco-sustainable alternative for the C–H arylation reactions.