Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands.

Veronica Paradiso,Fabia Grisi,Chiara Costabile

doi:10.3762/bjoc.14.292

Abstract

An overview on the catalytic properties of ruthenium complexes for olefin metathesis bearing monodentate unsymmetrical N-heterocyclic diaminocarbene ligands is provided. The non-symmetric nature of these NHC architectures strongly influences activity and selectivity of the resulting catalysts. The main achievements that have been accomplished in significant areas of olefin metathesis up to the current state of research are discussed.

Highlights

The transition metal-catalyzed olefin metathesis reaction is an indispensable synthetic tool for the construction of new carbon–carbon double bonds in various applications in both organic and polymer chemistry [1,2]
Significant advances in ruthenium metathesis catalyst design have been achieved by the introduction of unsymmetrically substituted N-heterocyclic carbene (NHC) ligands, namely presenting different substituents at the nitrogen atoms
The aim of the present review is to provide a description of the catalytic behavior of ruthenium complexes bearing monodentate five-membered unsymmetrically substituted NHC (uNHC)

Summary

Introduction

The transition metal-catalyzed olefin metathesis reaction is an indispensable synthetic tool for the construction of new carbon–carbon double bonds in various applications in both organic and polymer chemistry [1,2]. Ruthenium olefin metathesis complexes bearing N-heterocyclic carbene (NHC) ligands, known as second generation catalysts (Figure 1), have shown improved catalytic efficiency over other metathesis catalysts [3,4]. Their catalytic properties can be finely modulated through variation of the steric and electronic properties of the NHC ligand. Significant advances in ruthenium metathesis catalyst design have been achieved by the introduction of unsymmetrically substituted NHC (uNHC) ligands, namely presenting different substituents at the nitrogen atoms They offer the possibility of strongly influencing the reactivity and selectivity of the resulting catalysts by creating different steric and/or electronic environments around the metal center.

Objectives

Findings

Conclusion