2294-91-9Relevant academic research and scientific papers
Catalyst/cocatalyst nuclearity effects in single-site polymerization. Enhanced polyethylene branching and α-olefin comonomer enchainment in polymerizations mediated by binuclear catalysts and cocatalysts via a new enchainment pathway
Li, Liting,Metz, Matthew V.,Li, Hongbo,Chen, Ming-Chou,Marks, Tobin J.,Liable-Sands, Louise,Rheingold, Arnold L.
, p. 12725 - 12741 (2002)
The binuclear "constrained geometry catalyst" (CGC) (μ-CH2CH2-3,3′) {(η5-indenyl)[1-Me2Si- (tBuN)](ZrMe2}2 [EBICGC(ZrMe2)2; Zr2] and the trityl bisborate dianion (Ph3C+)2 [1,4-(C6F5) 3BC6F4B (C6F5)3]2- (B2) have been synthesized to serve as new types of multicenter homogeneous olefin polymerization catalysts and cocatalysts, respectively. Additionally, the complex [1-Me2Si(3-ethylindenyl)(tBuN)]ZrMe2 (Zr1) was synthesized as a mononuclear control. For the bimetallic catalyst or bisborate cocatalyst, high effective local active site concentrations and catalyst center-catalyst center cooperative effects are evidenced by bringing the catalytic centers together via either covalent or electrostatic bonding. For ethylene homopolymerization at constant conversion, the branch content of the polyolefin products (primarily ethyl branches) is dramatically increased as catalyst or cocatalyst nuclearity is increased. Moreover, catalyst and cocatalyst nuclearity effects are approximately additive. Compared to the catalyst derived from monometallic Zrl and monofunctional Ph3C+B (C6F5)4- (B1), the active catalyst derived from bimetallic Zr2 and bifunctional B2 produces ～11 times more ethyl branches in ethylene homopolymerization via a process which is predominantly intradimer in character. Moreover, ～3 times more 1-hexene incorporation in ethylene + 1-hexene copolymerization and ～4 times more 1-pentene incorporation in ethylene + 1-pentene copolymerization are observed for Zr2 + B2 versus Zr1 + B1.
Ir-catalyzed asymmetric hydrogenation of 3-arylindenones for the synthesis of chiral 3-arylindanones
Yan, Jun,Nie, Yu,Gao, Feng,Yuan, Qianjia,Xie, Fang,Zhang, Wanbin
supporting information, (2021/02/27)
An efficient synthesis of chiral 3-arylindanones via iridium-catalyzed asymmetric hydrogenation of 3-arylindenones has been developed. The reaction showed good compatibility with various functional groups, delivering a variety of 3-arylindanones in excellent yields and with good enantioselectivities. The reaction was also carried out on a gram-scale, delivering the product in quantitative yield. In addition, the products can be easily derivatized and transformed into natural products and pharmaceutical agents.
A HAFNIUM COMPLEX; A SUPPORTED HAFNIUM COMPLEX; METHODS OF FORMING A POLYMER USING SUCH COMPLEXES
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Paragraph 0061; 0062, (2018/12/13)
Embodiments of the present disclosure are directed towards metal complexes that can be utilized to form polymers. As an example, the present disclosure provides a metal complex of Formula I: wherein each Me represents methyl.
Gallium-assisted transfer hydrogenation of alkenes
Michelet, Bastien,Bour, Christophe,Gandon, Vincent
supporting information, p. 14488 - 14492 (2015/04/16)
We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1, 4-cyclo-hexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2][SbF6]. Hydrogenative cycli-zations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst.
A novel tandem [2 + 2] cycloaddition-Dieckmann condensation with ynolate anions. Efficient synthesis of substituted cycloalkenones and naphthalenes via formal [n + 1] cycloaddition
Shindo,Sato,Shishido
, p. 7818 - 7824 (2007/10/03)
A novel tandem [2 + 2] cycloaddition-Dieckmann condensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive β-lactone enolates via a pathway not involving the enolization of the corresponding β-lactones. The [2 + 2] cycloaddition of ynolate anions with δ- or σ-keto esters, followed by Dieckmann condensation, gives bicyclic β-lactones, which are easily decarboxylated to produce synthetically useful 2,3-disubstituted cyclopentenones and cyclohexenones in one pot. This tandem reaction was applied to a novel, one-pot synthesis of highly substituted naphthalenes.
Cross coupling of vinyl triflates and alkyl Grignard reagents catalyzed by niekel(0)-complexes
Busacca, Carl A.,Eriksson, Magnus C.,Fiaschi, Rita
, p. 3101 - 3104 (2007/10/03)
The scope and limitations of the Nickel(0)-catalyzed cross coupling of vinyl triflates with alkyl Grignard reagents have been studied. The effect of triflate substitution, solvent, and especially ligands have been examined. Ligands which are successful for sp2 and sp Grignard reagents fail for sp3 Grignard reagents.
Synthesis and reactions of [(((η6)-2-acylaryl)-C,O) tetracarbonylmanganese]-tricarbonylchromium complexes: Enhancement of diastereoselection during cyclopentaannulation
Clark, George R.,Metzler, Michael R.,Whitaker, Giles,Woodgate, Paul D.
, p. 109 - 134 (2007/10/03)
Cyclomanganation reactions of [(η6)-acylaryl]tricarbonylchromium complexes have been investigated. Three novel heterobimetallic complexes have been synthesised in moderate to good yield, with one being characterised by X-ray crystallography. Several modes of activating these bimetallic complexes towards coupling reactions with substituted alkenes and alkynes were investigated, including oxidative decarbonylation at room temperature, and thermal promotion. The stereochemistry of one of the cyclopentaannulated adducts has been established by X-ray crystallography. Thermal displacement of one of the CO ligands of the bimetallic complex 27 in the presence of PPh3 afforded a single adduct, the structure of which was established by X-ray crystallography. The chemistry of this novel bimetallic system was investigated.
Alkyl-substituted indenyl titanium precursors for syndiospecific ziegler-natta polymerization of styrene
Ready, Thomas E.,Chien, James C.W.,Rausch, Marvin D.
, p. 21 - 28 (2007/10/03)
A variety of 1- and 3-substituted alkylindenes (R = H, Me, Et, tert-butyl, Me3Si) as well as 2-methylindene and 3-(methylthio)indene have been prepared in good yields. The substituted indenes were converted into trimethylsilyl derivatives via reactions of intermediate organolithium complexes with chlorotrimethylsilane. The corresponding titanium complexes, (R-Ind)TiCl3, were synthesized in excellent yield from reactions of the trimethylsilyl derivatives with TiCl4. The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. Activities increased in the order: Cp 4 Ind 3Si, corresponding to an increase in the steric bulk of the substituent in the catalyst precursor. 1-(MeS)IndTiCl3 was found to be ineffective as a styrene polymerization catalyst. Syndiospecificities of the titanium complexes were generally very good (65-98%).
Rearrangement of Rigid Cyclopropylcarbinyl Radicals: Investigation of a Reporter System for the Detection of Very Short Lived Radicals
Lemieux, Robert P.,Beak, Peter
, p. 5454 - 5460 (2007/10/02)
The ring-opening rearrangements of the spiro-2'-yl radicals 1 and 2, the dispiro-2'-yl radical 3, and the 3',4'-dihydrospiro-2'-yl radicals 4 and 5 were investigated by the tin hydride method.At 75 deg C, the following unimolecular rate constants (kr) were obtained: 2.1 x 109 s-1 (1), 8.6 x 109 s-1 (2), 5.3 x 108 s-1 (3), 3.0 x 109 s-1 (4), and 3.6 x 109 s-1 (5).The rate of ring opening of the 3',3'-dimethylspiro-2'-yl radical 2 is comparable to that of the bicyclopent-2-yl radical and is one of the fastest cyclopropylcarbinyl radical rearrangements currently known.
Synthesis of Biological Markers in Fossil Fuels. 2. Synthesis and 13C NMR Studies of Substituted Indans and Tetralins
Adamczyk, Maciej,Watt, David S.,Netzel, Daniel A.
, p. 4226 - 4237 (2007/10/02)
Unambiguous syntheses of all possible methyl, ethyl, n-propyl, and n-butyl derivatives of indan and tetralin were developed using the Kumada coupling procedure involving the reaction of aryl or vinyl halides with Grignard reagents in the presence of nickel(II) chloride.An analysis of the 13C NMR spectra of these compounds was also completed.
