Phosphine ligands in the ruthenium-catalyzed reductive amination without an external hydrogen source

A systematic study of the phosphine additives influence on the activity of a ruthenium catalyst in reductive amination without an external hydrogen source was carried out. [CymeneRuCl(2)](2) was used as a reference catalyst, and a broad set of phosphines including Alk(3)P, Alk(2)ArP, Ar3P and X3P was screened. Three complexes of general formula (Cymene)RuCl2PR3 were isolated in a pure form, and their catalytic activity was compared with the in situ generated complexes. Nonhindered triarylphosphines with electron acceptor groups were found to be the most perspective activating agents, increasing the activity of the catalyst approx. six times, Alk(2)ArP ligands have less noticeable influence, while trialkylphosphines strongly deactivate the ruthenium catalyst. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A systematic study was conducted on the influence of phosphine additives on the activity of a ruthenium catalyst in reductive amination without an external hydrogen source. It was found that nonhindered triarylphosphines with electron acceptor groups are the most effective activating agents, while trialkylphosphines strongly deactivate the ruthenium catalyst.