One-pot reductive amination of aldehydes with nitroarenes using formic acid as the hydrogen donor and mesoporous graphitic carbon nitride supported AgPd alloy nanoparticles as the heterogeneous catalyst

Abstract

Herein, we report a one-pot protocol for the synthesis of secondary amines via a tandem reductive amination of aldehydes with nitroaromatics utilizing mesoporous graphitic carbon nitride (mpg-C₃N₄) supported AgPd alloy nanoparticles (mpg-C₃N₄/AgPd) as the catalyst, FA as the hydrogen donor and water as the sole solvent, which is a protocol in harmony with the green chemistry rules. In the present one-pot catalytic reductive amination protocol, a variety of secondary amines (11 examples) were yielded by using nitroarenes as a nitrogen source and benzaldehyde in the presence of the mpg-C₃N₄/AgPd nanocatalyst, which is the first example in the literature. Monodisperse AgPd alloy NPs (2.5 ± 0.5 nm) were synthesized by using our established protocol via the co-reduction of silver(I) acetate and palladium(II) acetylacetonate in the presence of oleylamine and oleic acid as surfactants in a hot organic solvent. The as-prepared AgPd alloy nanoparticles were then deposited on mpg-C₃N₄via a liquid phase self-assembly method. After the structural characterization of the mpg-C₃N₄/AgPd nanocatalyst using TEM, PXRD, BET and ICP-MS analyses, they were directly tested in one-pot direct reductive amination reactions in which they showed superior activity. The applicability of the present one-pot reductive amination strategy was demonstrated over a variety of aldehydes and nitroarenes (11 examples). Moreover, the mpg-C₃N₄/AgPd catalyst was a reusable catalyst in the reductive amination reactions providing 99% yield even after five consecutive runs.