Amination of aliphatic alcohols with urea catalyzed by ruthenium complexes: effect of supporting ligands

Abstract

In the present study, ruthenium-catalyzed amination of alcohols by urea as a convenient ammonia carrier in the presence of free diphosphine ligands has been described. A number of ruthenium-phosphine complexes have been studied among which, [(Cp)RuCl(dppe)] was found as an efficient catalyst for alcohol amination reaction. The crystal structures of two new half-sandwich ruthenium complexes, [(Cp)RuCl(dppe)] and [(C₆H₆)RuCl₂(PHEt₂)], were determined by X-ray crystallographic analysis. Also the effect of using different supporting phosphines, ratio of raw materials and reaction temperature on conversion and selectivity was investigated. Under optimum reaction conditions high conversion (98%) and chemo-selectivity toward secondary amines were obtained.

Keywords:

• Amination reaction
• urea
• half-sandwich ruthenium complex
• diphosphine ligands
• homogeneous catalyst
• borrowing hydrogen method

Acknowledgement

The authors gratefully acknowledge the financial support from Iran National Science Foundation (INSF).

Disclosure statement

No potential conflict of interest was reported by the authors.