Teaching Old Compounds New Tricks: DDQ-Photocatalyzed C-H Amination of Arenes with Carbamates, Urea, and N-Heterocycles

Abstract

The C-H amination of benzene derivatives was achieved using DDQ as photocatalyst and BocNH₂ as the amine source under aerobic conditions and visible light irradiation. Electron-deficient and electron-rich benzenes react as substrates with moderate to good product yields. The amine scope of the reaction comprises Boc-amine, carbamates, pyrazoles, sulfonimides and urea. Preliminary mechanistic investigations indicate arene oxidation by the triplet of DDQ to radical cations with different electrophilicity and a charge transfer complex between the amine and DDQ as intermediate of the reaction.

Keywords: C−H amination; charge-transfer complexes; electron-deficient arenes; heterocycles; photocatalysis.