A pincer ligand enabled ruthenium catalyzed highly selective N-monomethylation of nitroarenes with methanol as the C1 source

Abstract

A straightforward and highly selective N-monomethylation of nitro compounds with methanol as the C1 source was developed by employing [RuCl₂(p-cymene)₂]₂ as the catalyst and an NNN pincer (amine-pyridine-imine, API) as the ligand. This protocol was found to be highly selective and effective in the N-monomethylation of a broad spectrum of nitroarenes including pharmaceutically relevant nitro compounds with good tolerance of a set of functional groups. The mechanistic studies revealed that the reaction proceeded via a borrowing-hydrogen pathway in a one-pot cascade manner and methanol serves as both a hydrogen source and a methylation agent.