52772-46-0Relevant academic research and scientific papers
Stereochemistry and mechanism of vinyl-migrating [1,2]-Wittig rearrangement of α-lithioalkyl vinyl ethers
Tomooka, Katsuhiko,Inoue, Tadashi,Nakai, Takeshi
, p. 418 - 419 (2000)
Enantiomerically defined α-stannylalkyl or α-methylbenzyl vinyl ethers, when treated with butyllithium, are shown to undergo the 1,2-vinyl migration to afford the allylic alcohols in almost racemic form in low or high yield, respectively, thereby proposin
Structural elucidation of a methylenation reagent of esters: Synthesis and reactivity of a dinuclear titanium(iii) methylene complex
Kurogi, Takashi,Kuroki, Kaito,Moritani, Shunsuke,Takai, Kazuhiko
, p. 3509 - 3515 (2021/03/29)
Transmetallation of a zinc methylene complex [ZnI(tmeda)]2(μ-CH2) with a titanium(iii) chloride [TiCl3(tmeda)(thf)] produced a titanium methylene complex. The X-ray diffraction study displayed a dinuclear methylene structure [TiCl(tmeda)]2(μ-CH2)(μ-Cl)2. Treatment of an ester with the titanium methylene complex resulted in methylenation of the ester carbonyl to form a vinyl ether. The titanium methylene complex also reacted with a terminal olefin, resulting in olefin-metathesis and olefin-homologation. Cyclopropanation by methylene transfer from the titanium methylene proceeded by use of a 1,3-diene. The mechanistic study of the cyclopropanation reaction by the density functional theory calculations was also reported.
METHOD FOR PRODUCING SILYL SODIUM COMPOUND AND METHOD FOR DEOXIDIZING EPOXY COMPOUND
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Paragraph 0098-0102, (2020/05/06)
PROBLEM TO BE SOLVED: To construct a technique which can simply, efficiently and inexpensively synthesize a silyl sodium compound in a small number of processes and in a short time, especially to construct a technique which synthesizes a silyl sodium compound by using easily available reagents from a viewpoint of sustainability without using reagents which are difficult to handle and are toxic. SOLUTION: There is provided a method for synthesizing a silyl sodium compound comprising a step of reacting a dispersion obtained by dispersing a silyl halide compound or a disilane compound with sodium into a dispersion solvent, the silyl halide compound or the disilane compound as a starting compound, in a reaction solvent to obtain the silyl sodium compound. There is also provided a method for deoxidizing an epoxy compound comprising a step of reacting the silyl sodium compound obtained by synthesizing method of the silyl sodium compound with an epoxy compound to deoxidize the epoxy compound to stereoselectively produce an alkene compound. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPOandINPIT
Z-Selective Monothiolate Ruthenium Indenylidene Olefin Metathesis Catalysts
Smit, Wietse,Ekeli, Jonas B.,Occhipinti, Giovanni,Wo?niak, Bartosz,T?rnroos, Karl W.,Jensen, Vidar R.
, p. 397 - 407 (2020/02/13)
Ru-alkylidenes bearing sterically demanding arylthiolate ligands (SAr) constitute one of only two classes of catalyst that are Z-selective in metathesis of 1-alkenes. Of particular interest are complexes bearing pyridine as a stabilizing donor ligand, [RuCl(SAr)(a? CHR)(NHC)(py)] (R = phenyl or 2-thienyl, NHC = N-heterocyclic carbene, py = pyridine), which initiate catalysis rapidly and give appreciable yields combined with moderate to high Z-selectivity within minutes at room temperature. Here, we extend this chemistry by synthesizing and testing the first two such complexes (5a and 5b) bearing 3-phenylindenylidene, a ligand known to promote stability in other ruthenium-based olefin metathesis catalysts. The steric pressure resulting from the three bulky ligands (the NHC, the arylthiolate, and the indenylidene) forces the thiolate ligand to position itself trans to the NHC ligand, a configuration different from that of the corresponding alkylidenes. Surprisingly, although this configuration is incompatible with Z-selectivity and slows down pyridine dissociation, the two new complexes initiate readily at room temperature. Although their thermal stability is lower than that of typical indenylidene-bearing catalysts, 5a and 5b are fairly stable in catalysis (TONs up to 2200) and offer up to ca. 80% of the Z-isomer in prototypical metathesis homocoupling reactions. Density functional theory (DFT) calculations confirm the energetic cost of dissociating pyridine from 5a (= M1-Py) to generate 14-electron complex M1. Whereas the latter isomer does not give a metathesis-potent allylbenzene ?-complex, it may isomerize to M1-trans and M2, which both form ?-complexes in which the olefin is correctly oriented for cycloaddition. The olefin orientation in these complexes is also indicative of Z-selectivity.
Silica-supported Z-selective Ru olefin metathesis catalysts
Renom-Carrasco, Marc,Mania, Philipp,Sayah, Reine,Veyre, Laurent,Occhipinti, Giovanni,Jensen, Vidar R.,Thieuleux, Chloé
, (2020/01/21)
Recently reported thiolate-coordinated ruthenium alkylidene complexes show promise in Z-selective and stereoretentive olefin metathesis reactions. Herein we describe the immobilization of three Ru complexes containing a bulky aryl thiolate on mesostructured silica via surface organometallic chemistry. The applied methodology gives isolated catalytic sites homogeneously distributed on the silica surface. The catalytic results with two model substrates show comparable Z-selectivities to those of the homogeneous counterparts.
METHOD FOR SYNTHESIZING SODIUM 2,2,6,6-TETRAMETHYLPIPERIDIDES
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Paragraph 0096-0098, (2019/12/10)
There is a demand for the development of a technique according to which sodium 2,2,6,6-tetramethylpiperidides (Na-TMPs) can be economically and efficiently synthesized through simple operations including a small number of steps under mild conditions in a short period of time. Also, there is a demand for the development of a technique according to which high-quality Na-TMPs that do not contain lithium or lithium compounds such as Li-TMP can be synthesized. The method for synthesizing sodium 2,2,6,6-tetramethylpiperidides includes a step of obtaining sodium 2,2,6,6-tetramethylpiperidides by reacting, in a reaction solvent, 2,2,6,6-tetramethylpiperidines with a dispersion product obtained by dispersing sodium in a dispersion solvent or an organosodium compound having an aromatic ring obtained through a reaction with a dispersion product obtained by dispersing sodium in a dispersion solvent.
Supported Ru olefin metathesis catalysts: Via a thiolate tether
Renom-Carrasco, Marc,Mania, Philipp,Sayah, Reine,Veyre, Laurent,Occhipinti, Giovanni,Gajan, David,Lesage, Anne,Jensen, Vidar R.,Thieuleux, Chloé
supporting information, p. 2886 - 2890 (2019/03/07)
Thiolate-coordinated ruthenium alkylidene complexes can give high Z-selectivity and stereoretentivity in olefin metathesis. To investigate their applicability as heterogeneous catalysts, we have successfully developed a methodology to easily immobilize prototype ruthenium alkylidenes onto hybrid mesostructured silica via a thiolate tether. In contrast, the preparation of the corresponding molecular complexes appeared very challenging in solution. These prototype supported complexes contain small thiolates but still, they are slightly more Z-selective than their molecular analogues. These results open the door to more active and selective heterogeneous catalysts by supporting more advanced thiolate Ru-complexes.
IMPROVED OLEFIN METATHESIS CATALYSTS
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Page/Page column 40; 41, (2017/02/09)
The present invention refers to novel ruthenium-based catalysts for olefin metathesis reactions, particularly to fast initiating catalysts having stereoselective properties. In olefin metathesis reactions, the disclosed catalysts provide a high catalytic activity combined with the capability to generate higher yields of the olefin metathesis product.
Pyridine-Stabilized Fast-Initiating Ruthenium Monothiolate Catalysts for Z-Selective Olefin Metathesis
Occhipinti, Giovanni,T?rnroos, Karl W.,Jensen, Vidar R.
supporting information, p. 3284 - 3292 (2017/09/15)
Pyridine as a stabilizing donor ligand drastically improves the performance of ruthenium monothiolate catalysts for olefin metathesis in comparison with previous versions based on a stabilizing benzylidene ether ligand. The new pyridine-stabilized ruthenium alkylidenes undergo fast initiation and reach appreciable yields combined with moderate to high Z selectivity in self-metathesis of terminal olefins after only a few minutes at room temperature. Moreover, they can be used with a variety of substrates, including acids, and promote self-metathesis of ω-alkenoic acids. The pyridine-stabilized ruthenium monothiolate catalysts are also efficient at the high substrate dilutions of macrocylic ring-closing metathesis and resist temperatures above 100 °C during catalysis.
Molybdenum-Catalyzed Stereospecific Deoxygenation of Epoxides to Alkenes
Asako, Sobi,Sakae, Takahisa,Murai, Masahito,Takai, Kazuhiko
supporting information, p. 3966 - 3970 (2016/12/30)
Mild and simple catalytic systems consisting of molybdenum(VI) dichloride dioxide [MoO2Cl2] as a catalyst and a phosphine as reductant have been developed for the stereospecific deoxygenation of epoxides to alkenes. The reactions using 1,2-bis(diphenylphosphino)ethane (dppe) and triphenylphosphine (PPh3) proceed with retention and inversion of stereochemistry, respectively. The mild reaction tolerates the presence of various functional groups and affords stereodefined substituted olefins in good yields. (Figure presented.).
