Ionic polyamide boosting Ru efficiency in reductive amination of carbonyl compounds

The development of an efficient heterogeneous system for the selective synthesis of primary amines via reductive amination of carbonyl compounds has long been an important goal of chemical research. Here, we show that ionic polyamide stabilized Ru nanoparticles act as a broadly effective reductive amination catalyst, showing a high yield, large turnover frequency, stable recycling performance, and extendable substrate compatibility to a diverse set of alkane and aromatic primary amines. The ionic polyamide support provided a strong affinity towards the Ru species, enabling facile adjusting of the surface chemical state and dispersion. Metallic Ru0 species with high dispersion were achieved with a moderate loading amount, allowing a suitable hydrogenation ability that accelerated the rate-determining step in the reductive amination of a carboxyl compound, the ammonolysis of a Schiff base intermediate, and avoided side reactions such as direct hydrogenation to generate alcohols. The ionic moieties were found to be crucial for the stabilization of the Ru species that account for the stable recyclability.