Ruthenium diphosphine complexes as an efficient hydroamination catalyst

Bahareh Tamaddoni Jahromi,Ali Nemati Kharat,Mostafa M Amini,Hamidreza Khavasi

doi:10.1007/s13203-014-0095-5

Bahareh Tamaddoni Jahromi, Ali Nemati Kharat + Show 2 more

Open Access

https://doi.org/10.1007/s13203-014-0095-5

Copy DOI

Abstract

Ruthenium-catalyzed hydroamination of alkenes and alkynes with substituted anilines in the presence of various phosphine ligands have been investigated and catalyst activity and selectivity is improved. Ruthenium(II) complexes of diphenylphosphinomethane, diphenylphosphinoethane, diphenylphosphinopropane, diphenylphosphinobutane and diphenylphosphinopentane showed 50–90 % conversion under mild conditions. The effect of diphosphine ligands, substituent groups on anilines and reaction condition on the selectivity of hydroamination reaction were studied and the possible reaction mechanism was discussed. The reaction products were monitored by GC–MS and a mechanism for the hydroamination of alkenes and alkynes by ruthenium diphosphine complexes was proposed and discussed. The structures of two new complexes, C49H58Cl4P2Ru2 and C35H36Cl2P2Ru, as hydroamination catalysts were determined by X-ray crystallography.

Highlights

IntroductionAmong the various organic transformations, the direct addition of N–H bonds to alkenes and alkynes is a challenging and highly desirable reaction [2]
There are considerable interests in the development of efficient synthetic protocols for the construction of carbon–M
The reaction products were monitored by GC–MS and a mechanism for the hydroamination of alkenes and alkynes by ruthenium diphosphine complexes was proposed and discussed

Summary

Introduction

Among the various organic transformations, the direct addition of N–H bonds to alkenes and alkynes is a challenging and highly desirable reaction [2] In this respect, the transition metal-catalyzed hydroamination of olefins has been developed as an important tool for selective production of a large variety of amines and imines. As a continuation of our studies on these systems, we thought it is worth taking a detailed study of the reactivity of ruthenium–arene with bidentate phosphine ligands In this context, we have prepared several ruthenium(II) complexes with diphosphines ligands, diphenylphosphinomethane (dppm), diphenylphosphinoethane (dppe), diphenylphosphinopropane (dppp), diphenylphosphinobutane (dppb) and diphenylphosphinopentane (dpppe), and studied their catalytic activities in hydroamination of cycloolefins and alkynes. General procedure for the hydroamination of substituted anilines with cycloheptatriene Dichloro(p-cymene)ruthenium(II) dimer (2 mol%, 0.01– 0.02 mmol), diphosphine ligand (4 mol%, 0.02–0.04 mmol), and base additive (10 mol%, 0.05–0.10 mmol) were added directly into a 5-mL stainless steel autoclave. After 16 h, the autoclave was cooled to room temperature and the products were analyzed by gas chromatography

Findings

Result and discussion

Conclusions