A Bioinspired Diazafluorenone Catalytic System for Aerobic Oxidative Deamination of Primary Amines.

Copper amine oxidases (CAOs) catalyze aerobic oxidation of primary amines into carbonyl compounds, which is an important biological process as well as a useful transformation for organic synthesis. A new bioinspired organocatalyst, 1,8-diazafluoren-9-one (DFO), has been discovered, which exhibits impressive characteristics, including simple structure, high robustness, and strong electrophilicity, enabling it to effectively mimic the function of copper amine oxidases. Oxidative deamination of α-amino amides presents an attractive approach to access α-keto amides; however, it is difficult to achieve due to their electron-withdrawing nature and steric effect. The diazafluorenone displays high catalytic activity in this transformation, producing various biologically significant α-keto amides in moderate to excellent yields. Furthermore, the diazafluorenone catalyst is able to promote direct oxidation of benzylamines into aromatic aldehydes, instead of the generally formed product-reactant imines, which leads to no greater than 50% yields of the desired aldehydes. The current aerobic oxidative deamination proceeds via a pathway similar to the biological process, involving transamination, hydrolysis/aminolysis, and aerobic oxidation.