First ruthenium complexes with a chelating arene carbene ligand as catalytic precursors for alkene metathesis and cycloisomerisation

Çetınkaya, Bekır; Demır, Serpıl; Özdemır, İsmaıl; Toupet, Loı̈c; Sémeril, David; Bruneau, Christian; Dixneuf, Pierre H.

doi:10.1039/b100264n

Cited by 115 publications

(38 citation statements)

References 14 publications

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“…Yet, conversions were slightly lower and cycloisomerization took precedence over RCM, in line with the reduced metathetical activity of 3b compared to 3a. Reports from the groups of Kurosawa [31] and Dixneuf [32] had already established that selected monometallic ruthenium-arene complexes displayed such a dual activity. A mechanism involving oxidative coupling of the diene to a ruthenium(II) center followed by b-elimination to generate a hydrido-ruthenium(IV) intermediate and reductive elimination was proposed to account for the cycloisomerization process (Scheme 3).…”

Section: Catalytic Investigationsmentioning

confidence: 98%

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Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

et al. 2007

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where L = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (3a) or 1,3-bis(2,4,6-trimethylphenyl)-4,5-dichloroimidazolin-2-ylidene (3b), were isolated in high yields upon heating a toluene solution of [RuCl 2 A C H T U N G T R E N N U N G (p-cymene)] 2 with 1 equivalent of carbene ligand under an ethylene atmosphere. They were characterized by NMR and TGA. Their catalytic activity was investigated in the atom transfer radical polymerization of vinyl monomers. In the polymerization of methyl methacrylate, complex 3a displayed faster reaction rates than 3b and the related phosphine-based complex 2a (L = tricyclohexylphosphine), although control was more effective with the latter catalyst. When n-butyl acrylate or styrene served as monomer, a major shift of reactivity was observed between complex 2a that promoted controlled radical polymerization, and complexes 3a or 3b that favored metathetical coupling. Further homocoupling experiments with various styrene derivatives confirmed the outstanding aptitude of complex 3a (and to a lesser extent of 3b) to catalyze olefin metathesis reactions. Contrary to monometallic ruthenium-arene complexes of the [RuCl 2 A C H T U N G T R E N N U N G (p-cymene)(L)] type, the new homobimetallic species did not require the addition of a diazo compound or visible light illumination to initiate the ring-opening metathesis of norbornene or cyclooctene. When a,w-dienes were exposed to 3a or 3b, a mixture of cycloisomerization and ring-closing metathesis products was obtained in a non-selective way. Addition of a terminal alkyne co-catalyst enhanced the metathetical activity while completely repressing the cycloisomerization process. Thus, quantitative conversions of diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were achieved within 2 h at room temperature using 2 mol % of catalyst precursor 3 a and 6 mol % of phenylacetylene.

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Section: Catalytic Investigationsmentioning

confidence: 98%

“…[31,32] The alkyne co-catalyst probably reacts with coordinatively unsaturated ruthenium centers to form vinylidene species. Although less active than their alkylidene counterparts, complexes featuring an Ru=C=CHR moiety are wellknown initiators for various types of olefin metathesis, including ROMP and RCM (Scheme 4).…”

Section: Catalytic Investigationsmentioning

confidence: 99%

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

et al. 2007

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“…[14] As far as ruthenium is concerned, the main applications are in the field of olefin and enyne metathesis, [15] but a few examples have appeared in other catalytic reactions such as enyne cycloisomerization, [16] hydrogen transfer reduction of ketones, [17] oxidative cleavage of alkenes [18] or Friedlaender quinoline synthesis. [19] In a previous communication, we showed that N-alkylsubstituted benzimidazolylidene-ruthenium complexes were also efficient catalysts to perform regioselective alkylation of cinnamyl carbonate by dimethyl malonate and 1,3-diketones, as well as etherification of allylic halides by phenols, respectively.…”

Section: Introductionmentioning

confidence: 99%

Benzylic Imidazolidinium, 3,4,5,6‐Tetrahydropyrimidinium and Benzimidazolium Salts: Applications in Ruthenium‐Catalyzed Allylic Substitution Reactions

et al. 2008

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Imidazolidinium, tetrahydropyrimidinium and benzimidazolium salts were prepared. Upon reaction with tBuOK, they generate carbene ligands, which were associated in situ to [RuCp*(MeCN)3]PF6 to produce ruthenium catalysts that are active for the substitution of allylic substrates by dimethyl malonate as a carbonucleophile and phenol. The influences of the N‐heterocyclic structures, as well as that of the benzylic N‐substituents, on the reactivity and regioselectivity were examined.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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“…Complexes 6a-f, which are very stable in the solid state, have been characterized by analytical and spectroscopic techniques ( Table 1 (L = PCy 3 , 11,12 diaminocarbene. 30,31 ) to perform the ringclosing metathesis of dienes and ring opening of cyclic olefins, provided impetus to prepare the corresponding cationic ruthenium(allenylidene)(imidazoline) complexes according to the reaction depicted in Scheme 2. Indeed, purple complexes were prepared in dichloromethane but they were not stable enough to be isolated cleanly and characterized.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and catalytic properties of 1‐alkyl‐2‐imidazolineruthenium(II) complexes

Özdemır

Çetınkaya

Demır

et al. 2003

Applied Organom Chemis

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First ruthenium complexes with a chelating arene carbene ligand as catalytic precursors for alkene metathesis and cycloisomerisation

Cited by 115 publications

References 14 publications

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

Benzylic Imidazolidinium, 3,4,5,6‐Tetrahydropyrimidinium and Benzimidazolium Salts: Applications in Ruthenium‐Catalyzed Allylic Substitution Reactions

Synthesis and catalytic properties of 1‐alkyl‐2‐imidazolineruthenium(II) complexes

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