Reusable metal-free mesoporous carbon-catalyzed reductive N-formylation of nitroarenes and quinolines

Abstract

The high-value transformation of nitrogen-containing compounds through a facile, cost-effective, and eco-friendly one-pot strategy holds significant importance. However, this process typically involves the use of metal catalysts and is limited by low activity as well as the requirement of high temperature and pressure. Herein, we describe a general and efficient metal-free N-doped mesoporous carbon material using well-defined ligand 1,10-phenanthroline as the precursor and silica colloid as the hard template. Formic acid is both a reducing agent and a formylation reagent, and structurally distinct mono- or multi-substituted nitroarenes and quinolines can be selectively N-formylation in a one-pot method. The catalyst can be easily recovered without observable loss of efficiency for ten consecutive uses. The control experiments and density functional theory (DFT) calculations indicate that formic acid mainly obtains active hydrogen in the form of O–H bond cleavage, which benefits from the strong adsorption and enhanced activity generated by the interaction between graphitic nitrogen species in the catalyst and formic acid. The excellent catalytic performance of the meso-phen-X catalyst is attributed to the synergistic effect of graphitic N and large specific surface area, providing a promising method for the development of non-metallic catalyst-modified carbon materials.