Utilizing Nitroarenes and HCHO to Directly Construct Functional N-Heterocycles by Supported Cobalt/Amino Acid Relay Catalysis

Jia-Lu Sun, Chenggang Ci, Huanfeng Jiang, Pierre. H. Dixneuf, and Min Zhang*

Abstract: Due to the generation of multiple intermediates during the nitroarene reduction, precise interception of single one to develop tandem reactions involving both C–C and C–N bond formations still remains a significant challenge. Herein, the relay catalysis of a supported bifunctional cobalt catalyst with L-proline has been successfully applied to establish a bran-new reductive annulation reaction of nitroarenes and formaldehyde, which enables direct and diverse construction of both symmetrical and unsymmetrical 1,3-diaryl imidazolines. It proceeds with operational simplicity, good substrate and functionality compatibility, and excellent step and atom-efficiency. Mechanistic studies reveal that the Co-catalyst exhibits a synergistic effect on the formation of key N-hydroxy imine, and the L-proline subsequently facilitates the key C–C bond formation. The current work opens a door to develop useful transformations with nitroarenes by reduction-interrupted strategy.

Angew. Chem. Int. Ed., 2023, e202303007