Arene C–H Amination with N-Heteroarenes by Catalytic DDQ Photocatalysis

Arene C-H aminations using catalytic amounts of a 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) photocatalyst are described. Benzene, which has an oxidation potential of 2.48 V (vs SCE), was functionalized by pyrazoles, triazoles, tetrazoles, purines, and tert-butoxycarbonyl amine. Arenes underwent amination via a combination of ultraviolet (UV) light and a DDQ photocatalyst without a typical co-oxidant. Although the mechanism remains an open question, DDQH2, which is generated from DDQ after oxidation, is reactivated to DDQ under UV light irradiation conditions, possibly with the assistance of adventitious O2 and/or a solvent as the terminal oxidant(s) in this system.