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Metathesis Reactions (metathesis + reaction)
Kinds of Metathesis Reactions Selected AbstractsMetathesis Reaction of Hydrocarbyl Ligands across the Triruthenium Plane,ANGEWANDTE CHEMIE, Issue 34 2010Atsushi Tahara C3wechselt die Seite: Die Thermolyse eines Trirutheniumkomplexes mit einem ,3 -Pentylidin- und einem ,3 -Pentin-Liganden zu beiden Seiten der von den Metallatomen gebildeten Ebene führt ausschließlich zu einem ,3 -Ethylidin-,3 -octin-Komplex. Bei dieser Reaktion wandert ein C3 -Fragment von einer Seite der Ru3 -Ebene auf die andere, was in einer Umverteilung von zwei C5 - in ein C2 - und ein C8 -Molekül resultiert. [source] An Efficient Ring-Closing Metathesis Reaction of Geminally Disubstituted Olefins Using First Generation Grubbs, Catalyst: Enantiospecific Synthesis of Pacifigorgianes.CHEMINFORM, Issue 4 2004A. Srikrishna Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of Functionalized Pyrans by Domino Metathesis Reaction of Oxabicyclo Derivatives: Dramatic Effect of Remote Substituents on Reactivity and Selectivity.CHEMINFORM, Issue 16 2003Lynn C. Usher Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of trans-(3S)-Amino-(4R)-alkyl- and -(4S)-aryl-piperidines via Ring-Closing Metathesis Reaction.CHEMINFORM, Issue 16 2003X. Eric Hu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Progress Towards the Stereoselective Synthesis of 3,6-Disubstituted 1,2-Diamino-4-cyclohexenes by Ring Closing Metathesis Reaction.CHEMINFORM, Issue 15 2003Stefano Grilli Abstract For Abstract see ChemInform Abstract in Full Text. [source] Double Ring-Closing Metathesis Reaction of Nitrogen-Containing Tetraenes: Efficient Construction of Bicyclic Alkaloid Skeletons and Synthetic Application to Four Stereoisomers of Lupinine and Their DerivativesCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2004Shengming Ma Prof. Abstract The double ring-closing metathesis reaction of nitrogen-containing tetraenes was studied. The selectivity of the fused/dumbbell-type products can be controlled by the electronic/steric effects of the substituents attached to the CC bonds and the s - cis/s - trans conformational ratios of the substrates. This methodology has also been successfully applied to the enantioselective synthesis of four stereoisomers of lupinine and their derivatives. [source] Indenylidene-Ruthenium Complexes Bearing Saturated N-Heterocyclic Carbenes: Synthesis and Catalytic Investigation in Olefin Metathesis ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Stijn Monsaert Abstract The synthesis of complexes of the general formula Cl2Ru(SIMes)(L)(3-phenylinden-1-ylidene) (5, L = PCy3; 6, L = py; and 7, L = PPh3) from Cl2Ru(PR3)2(3-phenylinden-1-ylidene) (2a, R = Ph; 2b, R = Cy) is reported. This family of olefin metathesis catalysts was fully characterized (1H, 13C and 31P NMR spectroscopy and elemental analysis) and provided excellent activity in the ring-opening metathesis polymerization of 1,5-cyclooctadiene and the ring-closing metathesis of diethyl diallylmalonate. Comparison with the corresponding benzylidene-containing catalysts, 1a,c and 8b, established the decisive role of the carbene ligand on the procedure of the reaction and led to the observation of an unusual catalytic phenomenon, here called "self-inhibition".(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of a Hexadentate Hexameric Aluminum Imide and Its Metathesis ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003N. Dastagiri Reddy Abstract The reaction of AlH3·NMe3 with one equivalent of 2-cyanothiophene in toluene afforded [HAlNCH2(C4H3S)]6 (2) in good yield. Treatment of 2 with SiMe3Br and SiMe3Cl in toluene under refluxing conditions resulted in the formation of compounds [BrAlNCH2(C4H3S)]6 (3) and [ClAlNCH2(C4H3S)]6 (4), respectively. In a similar way [PhC,CAlNCH2(C4H3S)]6 (5) was readily obtained from the reaction between 2 and PhC,CH. When 2 was treated with PhSH the Al-N cluster core dissociated and a four-membered ring compound [(PhS)2AlNHCH2(C4H3S)]2 (6) was formed. In contrast, a similar hexameric aluminum imide (HAlNCH2Ph)6 (1) retains its Al-N network when treated with PhSH to yield (PhSAlNCH2Ph)6 (7). An exchange of ethyl groups and hydrides occurred when 2 was treated with excess of ZnEt2, forming [EtAlNCH2(C4H3S)]68. Compounds 2,4 and 6,8 were characterized by X-ray single-crystal analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Phenylphosphoric Acid as a New Additive to Inhibit Olefin Isomerisation in Ruthenium-Catalysed Metathesis ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2007Nélida Gimeno Abstract A systematic study of the ruthenium-catalysed metathesis of alkenes containing hydrogen-bonding substituents (namely urea and thiourea groups) is presented. Under standard metathesis conditions, several of the substrates under study undergo alkene isomerisation instead of the targeted metathesis. However, in the course of these investigations it has been established that this unwanted isomerisation process can be suppressed by addition of phenylphosphoric acid to the reaction mixture. Some other potential isomerisation inhibitors (e.g. benzoic acid and salts of phosphoric acid) have been studied and their performance compared to that of phenylphosphoric acid. To extend the scope of phenylphosphoric acid, we also studied the metathesis of 1,3-diallylurea. Interestingly, not only did we observe the complete suppression of the isomerisation process, but also that it is possible to obtain instead of the ring-closing metathesis (RCM) product,ADMET oligomers resulting from the cross-metathesis of diallylurea at higher concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Straightforward Synthesis of Labeled and Unlabeled Pyrimidine d4Ns via 2,,3, - Diyne seco Analogues through Olefin Metathesis ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2003Isabelle Gillaizeau Abstract The synthesis of dideoxynucleosides (ddNs) or didehydro-dideoxynucleosides (d4Ns) from nucleosides has been extensively reviewed. While previously described methods are based on the modification of the 2,- and/or 3,-OH group of the intact ribose moiety, the use of a ring-closing metathesis (RCM) for the formation of the unsaturated cyclic system of nucleosides could be a straightforward approach to the d4Ns. Thus, as part of our drug labeling program, this paper reports a straightforward synthesis of 2,,3,-didehydro-2,,3,-dideoxyuridine (d4U) and [1,,2,,3,,4,,5,- 13C5,6- 13C,1,3- 15N2]d4T using the RCM protocol. This paper discusses the preparation of nucleoside dienes and the activity of ruthenium-based metathesis catalysts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Mixed Isobutylphobane/N-Heterocyclic Carbene Ruthenium- Indenylidene Complexes: Synthesis and Catalytic Evaluation in Olefin Metathesis ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Xavier Sauvage Abstract Two new second generation ruthenium(II) dichloride-indenylidene complexes [RuCl2(9-isobutylphosphabicyclo[3.3.1]nonane)(NHC)(3-phenyl-1-indenylidene)], where NHC=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) or its unsaturated imidazol-2-ylidene analogue (IMes), were isolated in high yields upon heating a tetrahydrofuran (THF) solution of the diphosphane complex [RuCl2(isobutylphobane)2(3-phenyl-1-indenylidene)] with a two-fold excess of the corresponding imidazol(in)ium-2-carboxylate zwitterions. Both products were characterized by 1H, 13C, and 31P,NMR spectroscopy, and the molecular structure of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was determined by X-ray diffraction analysis. A close inspection of the packing structure revealed the presence of different types of intra- and intermolecular interactions that enhanced the global stability of the crystals, while low temperature NMR experiments showed the existence of two distinct rotational isomers due to the unsymmetrical nature of the phobane ligand. The catalytic activity of both compounds was assessed in olefin metathesis using benchmark ring-opening metathesis polymerization, ring-closing metathesis (RCM), and cross-metathesis reactions, and compared with those of related first and second generation ruthenium-benzylidene and indenylidene catalyst precursors. Kinetic studies confirmed the high thermal stability of the mixed isobutylphobane/N-heterocyclic carbene complexes, which suffered from a slow initiation efficiency compared to other catalytic systems based on the tricyclohexylphosphane ligand. However, the remarkable robustness of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was beneficial for performing the RCM of diethyl 2,2-bis(2-methylallyl)malonate. Monitoring the formation of the ruthenium-methylidene active species [RuCl2(isobutylphobane)(SIMes)(CH2)] derived from this precursor further demonstrated its ability to sustain long reaction times and high temperatures required to carry out the RCM of tetrasubstituted olefins. [source] Use of Commercially Available Ruthenium Fischer-Type Carbenes for Ring-Closing Metathesis Reactions: Scope and Limitations of an in situ Activation ProcedureADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Debra Abstract An evaluation of two commercially available Fischer-type ruthenium carbenes in a range of ring-closing diene and enyne metathesis reactions has been carried out. A method to activate such catalysts for ring-closing reactions is presented. [source] ChemInform Abstract: Ruthenium Catalysts Bearing Chelating Carboxylate Ligands: Application to Metathesis Reactions in Water.CHEMINFORM, Issue 22 2010Rafal Gawin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Tandem aza-Claisen Rearrangement and Ring-Closing Metathesis Reactions: The Stereoselective Synthesis of Functionalized Carbocyclic Amides.CHEMINFORM, Issue 40 2009Michael D. Swift Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A New Approach to Synthesis of Layered Fluorites Containing Molecular Anions: Synthesis of Ln2O2CO3, K(LnO)CO3, and Ln2O2CrO4 via Metathesis Reactions.CHEMINFORM, Issue 31 2008Dmitri O. Charkin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of N-Heterocyclic Compounds via Ene,yne Metathesis Reactions.CHEMINFORM, Issue 17 2008Elisabetta Groaz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] An Efficient Construction of Bicyclic Systems Containing a Seven-Membered Ring by Tandem Ring-Closing Metathesis Reactions of Dienynes.CHEMINFORM, Issue 19 2007Francois-Didier Boyer Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Convenient Approach to Tetrahydro-quinolizin-4-ones by Sequential Addition of Lithium Allyldibutylmagnesate to N-Allylpyridin-2-ones and Ring-Closing Metathesis Reactions.CHEMINFORM, Issue 1 2007Jacek G. Sosnicki Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Metathesis Reactions for the Synthesis of Ring-Fused Carbazoles.CHEMINFORM, Issue 18 2006Stephen C. Pelly Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Enyne and Dienyne Metathesis Reactions in ,-Carbolines.CHEMINFORM, Issue 5 2006Alvaro Gonzalez-Gomez Abstract For Abstract see ChemInform Abstract in Full Text. [source] Domino Metathesis Reactions for the Synthesis of Fused Tricyclic Frameworks.CHEMINFORM, Issue 28 2005Jacques-Alexis Funel Abstract For Abstract see ChemInform Abstract in Full Text. [source] A New Protocol for Benzoannulation by Double Claisen Rearrangement and Ring-Closing Metathesis Reactions as Key Steps.CHEMINFORM, Issue 26 2004Sambasivarao Kotha Abstract For Abstract see ChemInform Abstract in Full Text. [source] One-Pot Ring-Closing Metathesis-Alkene Cross Metathesis Reactions of Sulfamide-Linked Enynes.CHEMINFORM, Issue 25 2004Sofia S. Salim Abstract For Abstract see ChemInform Abstract in Full Text. [source] Control of Product Distribution in the Domino Metathesis Reactions of N-Alkynyl 2-Azabicyclo[2.2.1]hept-5-en-3-ones.CHEMINFORM, Issue 17 2004-Lactams, A Convenient Synthesis of Functionalized, Indolizidinones. Abstract For Abstract see ChemInform Abstract in Full Text. [source] An Efficient Method for Removal of Ruthenium Byproducts from Olefin Metathesis Reactions.CHEMINFORM, Issue 25 2003Jong Hyun Cho Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Cross Metathesis Reactions Using ,,,-Unsaturated Chromium Carbene Complexes.CHEMINFORM, Issue 36 2002Lei Zhang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Stereoselective Double Ring Closing Metathesis Reactions in the Synthesis of Spirocyclic Compounds.CHEMINFORM, Issue 28 2001Debra J. Wallace Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Surface-Grafted Multiporphyrin Arrays as Light-Harvesting Antennae to Amplify Photocurrent GenerationCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2005Mitsuhiko Morisue Dr. Abstract Organized multiporphyrin arrays were developed on the conductive surface by a novel coordination-directed molecular architecture aiming at efficient photoelectric conversion. The basic strategy employs the mutual coordination of two imidazolylporphyrinatozinc(II) units to form a cofacial dimer. Thus, meso,meso -linked bis(imidazolylporphyrinatozinc) (Zn2(ImP)2) was organized onto imidazolylporphyrinatozinc on the gold substrate as a self-assembled monolayer. The organized Zn2(ImP)2 bearing allyl side chains was covalently linked by ring-closing olefin metathesis catalyzed with Grubbs catalyst. Alternating coordination/metathesis reactions allow the stepwise accumulation of multiporphyrin arrays on the gold electrode. A successive increase in absorption over a wide wavelength range occurred after each accumulation step of Zn2(ImP)2 on the gold electrode, and cathodic photocurrent generation was enhanced in the aqueous electrolyte system, containing viologen as an electron carrier. The significant increase of the photocurrent indicates that the multiporphyrin array works as a "light-harvesting antenna" on the gold electrode. [source] Syntheses and Crystal Structures of Tetrakis(arylamidine)nickel(II) Chloride and Bis[2,4-dipyridyl-1,3,5-triazapentadienato]nickel(II)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2004Jianping Guo Abstract The reaction of LiN(SiMe3)2 with arylnitrile, followed by the addition of anhydrous NiCl2 gives ionic complexes of the general formula [Ni{H2NC(Ar)=NH}4]Cl2 (Ar = Ph 1, p -tolyl 2). When the above reaction is carried out with cyanopyridine instead of arylnitrile under the same reaction conditions, neutral complexes of the general formula [{HN=C(Py)N=C(Py)NH}2Ni] (Py = 4-pyridyl, 3; 3-pyridyl, 4] are obtained. Compound 1 undergoes a metathesis reaction with sodium benzoate to give the neutral complex [(PhCO2)2Ni {H2NC(Ph)=NH}4] (5). Magnetic susceptibility measurements show that 1,4 are diamagnetic and that 5 is paramagnetic with two unpaired electrons. These results suggest that 1,4 are d8 square-planar complexes and 5 is an octahedral complex. The solid state structures of compounds 1,5 were determined by X-ray crystallography. Structural analyses reveal that 1 and 2 form a one-dimensional network through charge-assisted hydrogen bonds; whereas 5 forms a one-dimensional network through hydrogen bonds only. In complexes 3 and 4, the 2,4-dipyridyl-1,3,5-triazapentadienyl ligand behaves as a bidentate ligand forming a six-membered ring with the metal ion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A Metathesis Approach for the Preparation of Polyhydroxylated Compounds as Head Groups in Surfactant SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2006Kristina Neimert-Andersson Abstract Starting from methyl-,- D -glucopyranoside, an efficient protocol for the preparation of polyhydroxylated surfactant head-groups is demonstrated and applied in the synthesis of a typical surfactant. The key transformation is a metathesis reaction between two monosaccharide residues to afford an octahydroxydecen. The importance of a strategic protecting-group constellation for a successful metathesis reaction is also investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] | ||||||||||||||||||||||||||||