- Catalyst
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A complex of formula (I): (I′) M is Hf; each X is a sigma ligand; L is a bridge of formula -(ER82)y—; y is 1 or 2; E is C or Si; each R8 is independently a C1-C20-hydrocarbyl, tri(C1-C20-alkyl)silyl, C6-C20- aryl, C7-C20-arylalkyl or C7-C20-alkylaryl or L is an alkylene group such as methylene or ethylene; Ar and Ar′ are each independently an aryl or heteroaryl group optionally substituted by 1 to 3 groups R1 or R1′ respectively; R1 and R1′ are each independently the same or can be different and are a linear or branched C1-C6-alkyl group, C7-20 arylalkyl, C7-20 alkylaryl group or C6-20 aryl group with the proviso that if there are four or more R1 and R1′ groups present in total, one or more of R1 and R1′ is other than tert butyl; R2 and R2′ are the same or are different and are a CH2—R9 group, with R9 being H or linear or branched C1-C6-alkyl group, C3-8 cycloalkyl group, C6-10 aryl group; each R is a —CH2—, —CHRx- or C(Rx)2-group wherein Rx is C1-4 alkyl and where m is 2-6; R5 is a linear or branched C1-C6-alkyl group, C7-20 arylalkyl, C7-20 alkylaryl group or C6-C20-aryl group; R6 is a C(R10)3 group, with R10 being a linear or branched C1-C6 alkyl group; and R6 and R7′ are the same or are different and are H or a linear or branched C1-C6-alkyl group. Invention relates also to a catalyst in solid form comprising (i) a complex of formula (I) and (ii) a cocatalyst of an aluminium compound and (iii) a cocatalyst of a boron compound.
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Paragraph 0426; 0467-0470
(2021/03/16)
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- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
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The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
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supporting information
p. 11730 - 11737
(2021/07/16)
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- PROCESS FOR PREPARING PROPYLENE COPOLYMERS COMPRISING C4-C12-ALPHA OLEFIN COMONOMER UNITS
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The present invention relates to a process for producing a copolymer of propylene, optionally ethylene, and at least one comonomer selected from alpha olefins having from 4 to 12 carbon atoms using a specific class of metallocene complexes in combination with a cocatalyst system comprising a boron containing cocatalyst and an aluminoxane cocatalyst, preferably in a multistage polymerization process including a gas phase polymerization step.
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Page/Page column 59-60
(2020/01/10)
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- CATALYSTS
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A complex of formula (I) wherein M is zirconium or hafnium; each X independently is a sigma ligand; L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, -R'2Ge-, wherein each R' is independently a hydrogen atom or a C1-C20-hydrocarbyl group optionally containing one or more silicon atoms or heteroatoms of Group 14-16 of the periodic table or fluorine atoms, and optionally two R' groups taken together can form a ring; R2 and R2' are each independently a C1-C20 hydrocarbyl group, -OC1- hydrocarbyl group or -SC1-20 hydrocarbyl group; R5 is a -OC1-20 hydrocarbyl group or -SC1-20 hydrocarbyl group, said R5 group being optionally substituted by one or more halo groups; R5' is hydrogen or a C1-20 hydrocarbyl group; -OC1-20 hydrocarbyl group or -SC1-20 hydrocarbyl group; said C1-20 hydrocarbyl group being optionally substituted by one or more halo groups; R6 and R6' are each independently a C1-20 hydrocarbyl group; -OC1-20 hydrocarbyl group or -SC1-20 hydrocarbyl group; each R1 and R1' are independently -CH2Rx wherein Rx are each independently H, or a C1-20 hydrocarbyl group, optionally containing heteroatoms.
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Page/Page column 49; 50
(2018/06/06)
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- Lewis acidity of organofluorophosphonium salts: Hydrodefluorination by a saturated acceptor
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Prototypical Lewis acids, such as boranes, derive their reactivity from electronic unsaturation. Here, we report the Lewis acidity and catalytic application of electronically saturated phosphorus-centered electrophilic acceptors. Organofluorophosphonium salts of the formula [(C6F 5)3-xPhxPF][B(C6F5) 4] (x = 0 or 1; Ph, phenyl) are shown to form adducts with neutral Lewis bases and to react rapidly with fluoroalkanes to produce difluorophosphoranes. In the presence of hydrosilane, the cation [(C 6F5)3PF]+ is shown to catalyze the hydrodefluorination of fluoroalkanes, affording alkanes and fluorosilane. The mechanism demonstrates the impressive fluoride ion affinity of this highly electron-deficient phosphonium center.
- Caputo, Christopher B.,Hounjet, Lindsay J.,Dobrovetsky, Roman,Stephan, Douglas W.
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p. 1374 - 1377
(2013/10/08)
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- Copper-catalyzed halogenation of arylboronic acids
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In this Letter, a copper-catalyzed halogenation of arylboronic acids was described. This reaction tolerates a variety of functional groups, providing aromatic halides with good yields. It represents a facile and mild procedure to aryl halides.
- Zhang, Guangyou,Lv, Guanglei,Li, Liping,Chen, Fan,Cheng, Jiang
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experimental part
p. 1993 - 1995
(2011/04/25)
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- Meta halogenation of 1,3-disubstituted arenes via iridium-catalyzed arene borylation
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We report the meta halogenation of 1,3-disubstituted arenes to form 3,5-disubstituted aryl bromides and chlorides by using iridium-catalyzed arene borylation chemistry. Iridium-catalyzed borylation of arenes with B2pin2, followed by reaction of the boronic ester with copper(II) bromide or chloride converts arylboronic esters to the corresponding aryl halides. A variety of arenes containing alkoxy, alkyl, halogen, nitrile, ester, amide, and pivaloyl and TIPS-protected alcohols were converted to the corresponding 3,5-disubstituted aryl bromides and chlorides in yields ranging from 46% to 85%. In addition, 2,6-disubstituted and 3-substituted pyridines were converted to the 4-halo and 5-halopyridines, respectively. The utility of this methodology was demonstrated by the formal conversion of nicotine to Altinicline in three steps with an overall yield of 61% using meta bromination of nicotine as the first step. Copyright
- Murphy, Jaclyn M.,Liao, Xuebin,Hartwig, John F.
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p. 15434 - 15435
(2008/09/19)
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- Room-temperature catalytic hydrodefluorination of C(sp3)-F bonds
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Room-temperature catalytic hydrodefluorination of the strong C(sp3)-F bonds in benzotrifluorides and fluoropentane is catalyzed by Et3Si[B(C6F5)4] and uses Et3SiH as the source of H. Ar-CF
- Scott, Valerie J.,Celenligil-Cetin, Remle,Ozerov, Oleg V.
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p. 2852 - 2853
(2007/10/03)
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- Electronic and steric effects of ligands as control elements for rhodium-catalyzed asymmetric hydrogenation
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Chiral diphosphine ligands analogous to bdpp have been synthesized and tested in order to study the effect of the electronic nature of the ligands in Rh-catalyzed asymmetric hydrogenation of some prochiral olefins. The results are compared with those obtained with the analogous unsubstituted ligand (bdpp). The rhodium-catalyzed asymmetric hydrogenation of olefins was influenced by ligand-based electronic effects, as well as substrate based ones. Excellent ee's (up to 98.3%) have been obtained in the rhodium-catalyzed hydrogenation of (Z)-α-acetamidocinnamic acids and esters.
- Herseczki, Zsanett,Gergely, Ildiko,Hegedues, Csaba,Szoellosy, Aron,Bakos, Jozsef
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p. 1673 - 1676
(2007/10/03)
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- COPPER-CATALYZED FORMATION OF CARBON-HETEROATOM AND CARBON-CARBON BONDS
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One aspect of the present invention relates to copper-catalyzed carbon-heteroatom and carbon-carbon bond-forming methods. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-sulfur bond between the sulfur atom of a thiol moiety and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In other embodiments, the present invention relates to copper(II)-catalyzed methods of forming a carbon-nitrogen bond between the nitrogen atom of an amide and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-carbon bond between the carbon atom of cyanide ion and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In another embodiment, the present invention relates to a copper-catalyzed method of transforming and aryl, heteroaryl, or vinyl iodide. Yet another embodiment of the present invention relates to a tandem method, which may be practiced in a single reaction vessel, wherein the first step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl iodide from the corresponding aryl, heteroaryl, or vinyl chloride or bromide; and the second step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl nitrile, amide or sulfide from the aryl, heteroaryl, or vinyl iodide formed in the first step.
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- Copper-catalyzed halogen exchange in aryl halides: An aromatic finkelstein reaction
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A mild and general method for the conversion of aryl, heteroaryl, and vinyl bromides into the corresponding iodides was developed utilizing a catalyst system comprising 5 mol % of Cul and 10 mol % of a 1,2- or 1,3-diamine ligand. A variety of polar functional groups are tolerated, and even N-H containing substrates such as sulfonamides, amides, and indoles are compatible with the reaction conditions. Both the reaction rate and the equilibrium conversion of the aryl bromide depend on the choice of the halide salt and the solvent. The best results were obtained using Nal as the halide salt and dioxane, n-butanol, or n-pentanol as the solvents. Copyright
- Klapars, Artis,Buchwald, Stephen L.
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p. 14844 - 14845
(2007/10/03)
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- The Triazene Moiety as a Protecting Group for Aromatic Amines
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Reaction of (2-), (3-), and (4-bromophenyl)-3,3-(1,4-butanediyl)triazenes (derived from the corresponding 2-, 3-, and 4-bromoanilines) with sec- or tert-butyllithiums gave the corresponding (triazenylaryl)lithiums; these intermediates reacted with a variety of electrophiles to give substituted aryl triazenes.These products could be converted to substituted anilines by reduction or to novel substituted aromatics by a modified Sandmeyer reaction.
- Gross, Margaret L.,Blank, David H.,Welch, Willard M.
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p. 2104 - 2109
(2007/10/02)
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- ONE STEP CONVERSION OF ANILINES TO ARYL HALIDES USING SODIUM NITRITE AND HALOTRIMETHYLSILANE
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Anilines were easily diazotized and efficiently converted to aryl halides in an one-pot reaction using sodium nitrite and halotrimethylsilane in carbon tetrachloride.Halotrimethylsilanes are used for both generating nitrosonium donor from sodium nitrite, and the halogen substitution of diazonium group.
- Lee, Jong Gun,Cha, Hee Tae
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p. 3167 - 3168
(2007/10/02)
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- Selective Nuclear Halogenation of Polymethylbenzenes with Alumina-Supported Copper(II) Halides
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The halogenation of polymethylbenzenes with alumina-supported copper(II) halides under heterogeneous conditions in nonpolar solvents gave nuclear-halogenated compounds selectively in high yields; no side-chain-halogenated compounds were formed.
- Kodomari, Mitsuo,Satoh, Hiroaki,Yoshitomi, Suehiko
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p. 4149 - 4150
(2015/06/25)
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- Asymmetric Synthesis. Asymmetric Catalytic Allylation Using Palladium Chiral Phosphine Complexes
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The general characteristics of asymmetric catalytic allylation are analyzed in terms of the properties of the allyl acetate substrates and of the putative (?-allyl)palladium(II) intermediates.After examining the diastereometric equilibria of a series of + complexes, it was established that anti-disposed ?-allyl substituents are the major source of discrimination and that aryl substituents cause an enhancement of the epimerization rate and also are responsible for the greatest discrimination.The ?-allyl substituents appear to contribute additively to the discrimination, and a sector rule is proposed for predicting diastereomeric equilibrium constants.Under appropriate conditions, it is proposed that the optical yields of asymmetric catalytic allylation can be predicted from the chiral discrimination found for these ?-allyl intermediates.These proposals were tested and optical yields of up to 86percent are reported.Quantitative chemical yields were obtained, catalysis can be performed at 25 degC, and the products are readily transformed into useful chirons.The optical yields are sensitive to the chiral phosphine used but are insensitive to the nature of the nucleophiles that were used.There is an approximate correlation of the optical yield with the previously observed diastereomeric ratio of the corresponding (?-allyl)palladium intermediate.All of the reactions are completely regioselective, and all of the nucleophiles used gave the same prevailing enantiomer of the product for a given chiral phosphine.
- Auburn, Pamela R.,Mackenzie, Peter B.,Bosnich, B.
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p. 2033 - 2046
(2007/10/02)
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- Protonation-induced Isomerization of Gaseous Bromoxylenes : a Radiolytic and Mass Spectrometric Study
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The isomerization of bromoxylenes following protonation by X3+ (X=H or D), CnH5+ (n=1 or 2), iso-C3H7+, and t-C4H9+ ions in the dilute gas state has been investigated.Further evidence has been derived from chemical ionization mass spectrometry and related radiolytic experiments concerning methylation of bromotoluenes by gaseous (CH3)2F+ ions.The results suggest that the observed intramolecular Br migration involves the intermediacy of a radical cation-bromine atom pair.The mechanistic relevance of the results to gas-phase aromatic substitution by free bromine cations is discussed.
- Cacace, Fulvio,Ciranni, Giovanna,Marzio, Annito Di
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p. 775 - 780
(2007/10/02)
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- Chemistry in Superacids. 6. Perfluoroalkanesulfonic Acid-Boron Perfluoroalkanesulfonates: New Superacid Systems for Generation of Carbocations and Catalysts for Electrophilic Transformations of Hydrocarbons
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Boron trihalides (BX3, X = Cl, Br) react with excess perfluoroalkanesulfonic acids to give conjugate superacids of the type RFSO2OH2+F)4>- (RF = CF3, C4F9, and C10F21).The systems were characterized by spectroscopy and their chemical (catalytic) properties were studied.The parent of the series CF3SO3H2+- (1) (first reported by Engelbrecht and Tschager) was found to O-protonate ketones and to generate stable tert-alkyl- and methyl-substituted benzylic cations at low temperature in SO2ClF.Stable ions are similarly generated in B(OSO2CF3)3/SO2ClF.The catalytic activity of the conjugate superacid 1 has been demonstrated in transbromination/transalkylation of aromatics as well as in isomerization of n-butane, n-hexane, and trimethylenenorbornane to adamantane under mild conditions.
- Olah, George A.,Laali, Khosrow,Farooq, Omar
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p. 4591 - 4594
(2007/10/02)
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- Synthesis of Some Bicyclophanes
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Bicyclic aromatic compounds, bicyclophanehexanes of general structure A, have been obtained from sixfold Wittig reactions between aromatic bisphosphonium salts and 1,3,5-benzenetricarbaldehyde.Hydrogenation gave bicyclophanes of structure B.The synthesis of bicyclophanes from ylids prepared from the bisphosphonium salts from 1,3- and 1,4-bis(bromomethyl)benzene, 1,3-bis(bromomethyl)-5-bromobenzene, and 2,5-bis(chloromethyl)thiophene is described and the structures of the bicyclophanes discussed.
- Hoegberg, Hans-Erik,Wennerstroem, Olof
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p. 661 - 668
(2007/10/02)
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