Ruthenium-catalyzed reductive amination of ketones with nitroarenes and nitriles

The Ru(dppbsa)-catalyzed reductive amination of ketones with nitroarenes and nitriles using H-2 as the environmentally benign hydrogen surrogate is developed in this study. Cross-experiments demonstrated that both reactions are initiated by the reduction of nitroarenes or nitriles to the corresponding amines, followed by condensation with ketones to give imines and thereafter hydrogenation. However, the route to the formation of an amino-ligated Ru complex during the reduction of nitroarenes or nitriles, followed by in situ nucleophilic C-N coupling, cannot be completely excluded. This newly developed versatile method features good functional group tolerance, which provides a novel design platform for homogeneous catalysts in constructing motifs of secondary amines.

Automated summary

The Ru(dppbsa)-catalyzed reductive amination of ketones with nitroarenes and nitriles using H-2 as the hydrogen surrogate has been developed. It was found that both reactions proceed through reduction of nitroarenes or nitriles to amines, followed by condensation with ketones to form imines and subsequent hydrogenation. However, the possibility of formation of an amino-ligated Ru complex and in situ nucleophilic C-N coupling during the reduction cannot be completely ruled out. This versatile method allows for good functional group tolerance and provides a new design platform for homogeneous catalysts in the synthesis of secondary amines.