Reductive Amidation of Nitroarenes on Nitrogen-Coordinated Single-Site Palladium Catalysts

Abstract

N-aryl amides are essential in pharmaceuticals and fine chemicals, with one-pot reductive amidation of nitroarenes providing a straightforward synthesis approach. To enhance the catalyst stability under reducing conditions, four single-Pd-site catalysts with N, O, P, and I heteroatoms were developed. Among them, the Pd₁/NC catalyst achieved excellent ∼100% conversion of nitrobenzene, 90% selectivity for acetanilide, and a turnover frequency (TOF) of 681 h^–1, with no obvious decay after six cycles in an autoclave reactor and over 220 h in a fixed-bed durability test. Various substrates further showed the universality for the reductive amidation of nitroaromatics on robust single-Pd-site catalysts. The Pd–N coordination facilitated H₂ activation and stabilized the single Pd^δ+ ions. In situ DRIFTS and control experiments confirmed a mechanism involving PhNO and PhNH₂ intermediates. This work provides valuable insights into the design of highly stable single-Pd-site catalysts for reductive amidation.