Aerobic CuCl2‑Catalyzed Dehydrogenative Cross-Coupling of Tertiary Amines. A Combined Computational and Experimental Study

The generation of an iminium from amines is a way to functionalize the α carbon by coupling reactions. The reaction mechanism of the conversion of tertiary amines to iminium with CuCl2(H2O)2 as catalyst in aerobic conditions has been computationally and experimentally studied in this work. This process is initiated by the oxidation of the amine to a radical cation dichlorocuprate through the reduction of CuII to CuI. Then, the iminium dichlorocuprate is generated from the radical-ion through a hydrogen-transfer. The H atom can be accepted by molecular oxygen or by a second molecule of catalyst (in anaerobic conditions). Therefore, O2 also assumes the important role of acceptor along with that of regenerator of the catalyst. The experimental study confirmed the computational study and lead to the synthesis of four new molecules from the cross-coupling of N,N-diethyl- and N,N-diisoproylaniline with nitromethane and dimethylmalonate.