Photochemical C3-amination of pyridines via Zincke imine intermediates
Kitti Franciska Szabó, Piotr Banachowicz, Antoni Powała, Danijela Lunic, Ignacio Funes‐Ardoiz, Dorota Gryko
Abstract
Selective skeletal and peripheral editing of the pyridine moiety has broadly expanded the chemical space. While C-H functionalization at C2 and C4 positions are enabled by the inherent reactivity of this heteroarene, selective derivatization at the C3 position has long posed a significant challenge. Recently, based on a dearomatization-rearomatization sequence, involving Zincke imine intermediates, selective halogenation (-Br, -Cl, and -I) and isotopic labelling were accomplished. Here, we report a mild and regioselective method for C3-amination that relies on the photochemical reaction of Zincke imine with an amidyl radical generated from N-aminopyridinium salts. Mechanistic and theoretical studies indicate that radical intermediates are involved and explain the C3 regioselectivity of the reaction.