A Novel Class of Ruthenium Catalysts for Olefin Metathesis

Abstract

The different nature of carbene ligands is clearly demonstrated by the first ruthenium-based complexes 1, which contain both alkylidene and N-heterocyclic carbene moieties. The latter exhibit a pronounced Lewis base behavior. Moreover, this difference forms the basis of the high catalytic activities of these compounds in olefin metathesis reactions.

Halide exchanged Hoveyda-type complexes in olefin metathesis

“…Since the pioneering reports on the utilisation of N -heterocyclic carbenes (NHC) as co-ligands in ruthenium-based carbene complexes for olefin metathesis [1–3] in the late nineties of the last century, olefin metathesis has become a powerful carbon-carbon double-bond-forming tool presenting unique synthetic opportunities [4]. Developments in this area can be attributed to a steady and competitive research, focused on improving activity, selectivity and functional group tolerance of the catalysts by changing the leaving co-ligand [4–5], by using tailored carbene ligands [5–7], by introducing new NHC ligands [5,8–9], or by variation of the anionic co-ligands [5] (Fig.…”

Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

“…Mixed complexes bearing both a phosphane and a NHC ligand, so-called 2 nd generation catalysts, typically display better thermal stability and activities compared to 1 st generation catalysts [9–10]. Key to the success and research activity involving 2 nd generation catalysts has been the wide selection of NHCs available [11–12].…”

N -Heterocyclic Carbene Metal Complexes as Bio-Organometallic Antimicrobial and Anticancer Drugs

“…Although NHC-metal complexes have been known particularly as catalysts [12,15,[21][22][23][24][25][26][27] for various chemical transformations, later discoveries showed that these complexes can be used in medical applications [84][85][86][87][88][89]. Developments of NHC-metal complexes as anticancer agents have been comprehensively reviewed in the recent past by Deng et al [90] and Bhagat et al [91].…”

“…Reduced cross resistance to cisplatin, decreased toxicity and high specificity of many new mononuclear, dinuclear and multinuclear palladium complexes have been developed. Palladium complexes might materialize a concept of tumor targeting which would result in drugs with other spectrum of activity 103 -HCT 119 [116] 104 26.5 HCT 119 [116] 105 6.6 HCT 119 [116] t-Bu NH future science group N-heterocyclic carbene metal complexes as bio-organometallic antimicrobial & anticancer drugs Review and lack of cross-resistance as compared with platinum drugs [30,103,141].…”

“…The NHCs have several advantages over the commonly utilized phosphines: the strong σ-donating ability, coupled with its minimal π-back bonding capabilities results in strong stabilizing effects and resistance to dissociation from the metal center; the strong NHC-metal bond and limited complex decomposition pathways ensure high thermal stability of derived carbene complexes [16][17][18][19][20]. A wide range of NHC-metal derivatives have been used as catalysts in many chemical transformations over many years [12,15,[21][22][23][24][25][26][27]. Applications of NHC-metal complexes other than catalysis are remarkably scarce.…”