- Synthesis, spectroscopic characterization and catalytic activity of platinum(II) carbene complexes
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A novel platinum complex with 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidenyl ligand has been synthesized and characterized on the basis of elemental analysis, MS, 1H and 13C NMR spectroscopy, X-ray Absorption Spect
- Bolbat, Ekaterina,Suarez-Alcantara, Karina,Canton, Sophie E.,Wendt, Ola F.
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- The two faces of platinum hydrospirophosphorane complexes—Not only relevant catalysts but cytotoxic compounds as well
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Platinum complexes [PtCl2(L)] L = L1, L2 with symmetrical HP (OCH2CMe2NH)2 (L1) and unsymmetrical HP(OCMe2CMe2O)(OCH2CMe2NH) (L2) hydrospirophosphorane (HSP) ligands were demonstrated to play a dual role of catalysts and cytotoxic compounds as well. The structure of new complex [PtCl2(L2)] was confirmed by physicochemical and spectroscopic methods, as well as single X-ray diffraction studies for [PtCl2{P (OCMe2CMe2O)(OCH2CMe2NH2)}]. HSP ligand coordinated to the platinum center in bidentate κ2-P,NH2 chelating mode of fashion. Both complexes were found to exhibit catalytic activity for Heck cross-coupling reactions of iodobenzene with substituted styrenes, with good conversion and yield of stilbenes. Moreover, complexes have been applied as excellent catalysts for highly regioselective hydrosilylation of aromatic and aliphatic terminal olefins, and acetylenes terminal and internal as well. On the other hand, the preliminary biological studies revealed that in the presence of foretinib, drug candidate in clinical trials for the treatment of cancer, platinum complexes revealed increased synergistic effect and efficiently decreased the number of viable cells of triple negative breast cancer MDA-MB-231 cell line.
- Skar?yńska, Anna,Kowalczyk, Marta,Majchrzak, Mariusz,Pi?tka, Marta,Augustyniak, Adam W.,Siczek, Mi?osz,W?odarczyk, Kinga,Simiczyjew, Aleksandra,Nowak, Dorota
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- 14-Electron Rh and Ir silylphosphine complexes and their catalytic activity in alkene functionalization with hydrosilanes
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Herein we report an experimental and computational study of a family of four coordinated 14-electron complexes of Rh(iii) devoid of agostic interactions. The complexes [X-Rh(κ3(P,Si,Si)PhP(o-C6H4CH2SiiPr2)2], where X = Cl (Rh-1), Br (Rh-2), I (Rh-3), OTf (Rh-4), Cl·GaCl3(Rh-5); derive from a bis(silyl)-o-tolylphosphine with isopropyl substituents on the Si atoms. All five complexes display a sawhorse geometry around Rh and exhibit similar spectroscopic and structural properties. The catalytic activity of these complexes and [Cl-Ir(κ3(P,Si,Si)PhP(o-C6H4CH2SiiPr2)2],Ir-1, in styrene and aliphatic alkene functionalizations with hydrosilanes is disclosed. We show thatRh-1catalyzes effectively the dehydrogenative silylation of styrene with Et3SiH in toluene while it leads to hydrosilylation products in acetonitrile.Rh-1is an excellent catalyst in the sequential isomerization/hydrosilylation of terminal and remote aliphatic alkenes with Et3SiH including hexene isomers, leading efficiently and selectively to the terminal anti-Markonikov hydrosilylation product in all cases. With aliphatic alkenes, no hydrogenation products are observed. Conversely, catalysis of the same hexene isomers byIr-1renders allyl silanes, the tandem isomerization/dehydrogenative silylation products. A mechanistic proposal is made to explain the catalysis with these M(iii) complexes.
- Abeynayake, Niroshani S.,Donnadieu, Bruno,Gorla, Saidulu,Montiel-Palma, Virginia,Mu?oz-Hernández, Miguel A.,Zamora-Moreno, Julio
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supporting information
p. 11783 - 11792
(2021/09/06)
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- Accelerated Anti-Markovnikov Alkene Hydrosilylation with Humic-Acid-Supported Electron-Deficient Platinum Single Atoms
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The hydrosilylation reaction is one of the largest-scale applications of homogeneous catalysis, and Pt homogeneous catalysts have been widely used in this reaction for the commercial manufacture of silicon products. However, homogeneous Pt catalysts result in considerable problems, such as undesired side reactions, unacceptable catalyst residues and disposable platinum consumption. Here, we synthesized electron-deficient Pt single atoms supported on humic matter (Pt1@AHA_U_400), and the catalyst was used in hydrosilylation reactions, which showed super activity (turnover frequency as high as 3.0×107 h?1) and selectivity (>99 %). Density functional theory calculations reveal that the high performance of the catalyst results from the atomic dispersion of Pt and the electron deficiency of the Pt1 atoms, which is different from conventional Pt nanoscale catalysts. Excellent performance is maintained during recycle experiments, indicating the high stability of the catalyst.
- Antonietti, Markus,Badamdorj, Bolortuya,Janik, Michael J.,Liu, Kairui,Yang, Fan
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supporting information
p. 24220 - 24226
(2021/10/07)
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- A family of rhodium(i) NHC chelates featuring O-containing tethers for catalytic tandem alkene isomerization-hydrosilylation
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The rhodium complex Rh(HL)(COD)Cl, 1, L being a functionalized N-heterocyclic carbene (NHC) ligand with an oxygen-containing pendant arm, has been used as the entry point to synthesize a series of neutral and cationic Rh(i) O,C chelates. While the Rh-carbene interaction is similar in all these 16-electron complexes, structural analysis reveals that the strength of the Rh-O bond is greatly affected by the nature of the O-donor: R-O- > R-OH > R-OBF3. These subtle changes in the nature of the O-containing tether are found to be responsible for large differences in the alkene hydrosilylation catalytic activity of these compounds: the stronger the Rh-O interaction, the better the catalytic performances. The most active catalyst, [Rh(L)(COD)], 2, demonstrated good catalytic activity under mild reaction conditions for the hydrosilylation of a range of alkene substrates with the industrially relevant non-activated tertiary silane, 1,1,1,3,5,5,5-heptamethyltrisiloxane (MDHM). Furthermore, this complex is an effective catalyst for the selective remote functionalization of internal olefins at room temperature via tandem alkene isomerization-hydrosilylation.
- Srivastava, Ravi,Jakoobi, Martin,Thieuleux, Chloé,Quadrelli, Elsje Alessandra,Camp, Clément
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p. 869 - 879
(2021/02/03)
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- Developing a Highly Active Catalytic System Based on Cobalt Nanoparticles for Terminal and Internal Alkene Hydrosilylation
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This work describes the development of easy-To-prepare cobalt nanoparticles (NPs) in solution as promising alternative catalysts for alkene hydrosilylation with the industrially relevant tertiary silane 1,1,1,3,5,5,5-heptamethyltrisiloxane (MDHM). The Co NPs demonstrated high activity when used at 30 °C for 3.5-7 h in toluene, with catalyst loadings 0.05-0.2 mol %, without additives. Under these mild conditions, a set of terminal alkenes were found to react with MDHM, yielding exclusively the anti-Markovnikov product in up to 99% yields. Additionally, we demonstrated the possibility of using UV irradiation to further activate these cobalt NPs not only to enhance their catalytic performances but also to promote tandem isomerization-hydrosilylation reactions using internal alkenes, among them unsaturated fatty ester (methyl oleate), to produce linear products in up to quantitative yields.
- Jakoobi, Martin,Dardun, Vincent,Veyre, Laurent,Meille, Valérie,Camp, Clément,Thieuleux, Chloé
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p. 11732 - 11740
(2020/10/23)
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- [Rh(Cod)Cl]2/Pph3?catalyzed dehydrogenative silylation of styrene derivatives with NBE as a hydrogen acceptor
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Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]2/ PPh3-catalyzed dehydrogenative silylation of styrene derivatives with R3SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE) and PPh3 play a key role in achieving excellent selectivity in the formation of dehydrogenative silylation products. Moreover, this high-yielding transformation exhibits a broad substrate scope and good functional group tolerance.
- Li, Chengyang,Lu, Wenkui,Wu, Xiaoyu,Xie, Xiaomin,Zhang, Zhaoguo
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p. 3780 - 3788
(2020/11/23)
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- Diverse Fates of β-Silyl Radical under Manganese Catalysis: Hydrosilylation and Dehydrogenative Silylation of Alkenes
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Manganese-catalyzed hydrosilylation of alkenes has been underdeveloped for a long time. Herein, we describe a general, chemo- and regio- selective hydrosilylation of alkenes by using the Mn(CO)5Br catalyst with ample substrate scopes. Meanwhile, dehydrogenative silylation of aryl olefins can be selectively achieved upon the catalysis of dinuclear Mn2(CO)10. Mechanistic experiments revealed diverse fates of the common intermediate β-silyl radical, namely, hydrogen atom transfer (HAT) for the hydrosilylation and organometallic β-H elimination for the dehydrogenative silylation of olefins.
- Yang, Xiaoxu,Wang, Congyang
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supporting information
p. 1047 - 1051
(2018/09/27)
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- Regio- and Stereoselective Dehydrogenative Silylation and Hydrosilylation of Vinylarenes Catalyzed by Ruthenium Alkylidenes
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Development of regio- and stereoselective dehydrogenative silylation and hydrosilylation of vinylarenes with alkoxysilanes, catalyzed by ruthenium alkylidenes, is described. Varying L- and X-type ligands on ruthenium alkylidenes permits selective access to either (E)-vinylsilanes or β-alkylsilanes with high regio- and stereocontrol. cis,cis-1,5-Cyclooctadiene was identified as the most effective sacrificial hydrogen acceptor for the dehydrogenative silylation of vinylarenes, which allows use of a nearly equimolar ratio of alkenes and silanes.
- Bokka, Apparao,Jeon, Junha
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supporting information
p. 5324 - 5327
(2016/11/02)
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- Base-Metal-Catalyzed Regiodivergent Alkene Hydrosilylations
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A complementary set of base metal catalysts has been developed for regiodivergent alkene hydrosilylations: iron complexes of phosphine-iminopyridine are selective for anti-Markovnikov hydrosilylations (linear/branched up to >99:1), while the cobalt complexes bearing the same type of ligands provide an unprecedented high level of Markovnikov selectivity (branched/linear up to >99:1). Both systems exhibit high efficiency and wide functional group tolerance. Regiodivergent alkene hydrosilylation has been accomplished with high efficiency using a newly developed set of complementary base metal catalyst systems. An inversion of regioselectivity (linear/branched) from >99:1 to 1:99 is obtained when the iron version of the catalyst is exchanged for a cobalt-containing analogue.
- Du, Xiaoyong,Zhang, Yanlu,Peng, Dongjie,Huang, Zheng
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supporting information
p. 6671 - 6675
(2016/06/08)
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- The cobalt(II) complex of a new tridentate Schiff-base ligand as a catalyst for hydrosilylation of olefins
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Condensation of 1-methyl-2-imidazolecarboxaldehyde with 2-(1-methylhydrazinyl)pyridine results in the synthesis of new, tridentate Schiff-base ligand L, which readily reacts with CoCl2 to form a monometallic [CoLCl2] complex that, upon reduction, functions as active hydrosilylation catalyst. The ligand and the [CoLCl2] catalyst have been characterized spectroscopically (MS, NMR, FTIR) and by single crystal X-ray diffraction techniques. The results of preliminary catalytic experimentation show that the cobalt complex can induce hydrosilylation and dehydrogenative silylation of olefins, depending upon the hydrosilane substrate used.
- Gorczyński, Adam,Zaranek, MacIej,Witomska, Samanta,Bocian, Aleksandra,Stefankiewicz, Artur R.,Kubicki, MacIej,Patroniak, Violetta,Pawlu?, Piotr
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- Combinatorial Approach to the Catalytic Hydrosilylation of Styrene Derivatives: Catalyst Systems Composed of Organoiron(0) or (II) Precursors and Isocyanides
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(COT)2Fe and the open ferrocenes (MPDE)2Fe (MPDE = η5-3-methylpentadienyl) and (DMPDE)2Fe (DMPDE = η5-2,4-dimethylpentadienyl) were found to function as catalyst precursors for the hydrosilylation of alkenes in the presence of auxiliary ligands. Screening trials determined that the optimal catalyst system was composed of (COT)2Fe and adamantyl isocyanide, allowing the selective hydrosilylation of styrene derivatives with trisubstituted hydrosiloxanes and a polydimethylsiloxane bearing Me2SiH moieties as the end groups. Under the appropriate conditions, the dehydrogenative silylation side reaction was completely suppressed, and the reaction TON exceeded 5000. (Chemical Equation Presented).
- Sunada, Yusuke,Noda, Daisuke,Soejima, Hiroe,Tsutsumi, Hironori,Nagashima, Hideo
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supporting information
p. 2896 - 2906
(2015/06/30)
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- Synthesis, Characterization, Crystal Structures, and Catalytic C-C Coupling and Hydrosilylation Reactions of Palladium(II) Complexes Derived from CNC Pincer-Type N-Heterocyclic Carbenes
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A series of pyridine linker containing bis(benz)imidazolium salts serving as precursors to CNC pincer-type N-heterocyclic carbene (NHC) ligands were prepared by successive N-alkylation of the azole core. Binuclear NHC complexes of silver(I) were synthesized by in situ deprotonation of the corresponding (benz)imidazolium salt with silver(I) oxide in acetonitrile at elevated temperature in the dark. Subsequently, pincer-type palladium(II)-NHC complexes were prepared by transmetalation using silver(I)-NHC complexes in acetonitrile at elevated temperatures. All compounds were fully characterized by elemental analysis, FTIR spectroscopy, and 1H and 13C NMR spectroscopy. X-ray diffraction studies on single crystals of three compounds confirmed the distorted square-planar geometry around the palladium(II) center. All complexes are monomeric in nature, and the bis-NHC ligand chelates in the CNC mode. The effective catalytic potentials of the palladium complexes were demonstrated by their high activities in aqueous-phase Suzuki-Miyaura and Heck-Mizoroki cross-coupling reactions of phenylboronic acid and n-butyl acrylate with a range of functionalized bromobenzene derivatives. The former coupling reaction afforded biphenyls in yields of 71-99%, whereas the latter reaction evidenced low yields of the n-butyl cinnamates. Further, all the palladium complexes were studied for their potential in a catalytic hydrosilylation reaction.
- Haque, Rosenani A.,Asekunowo, Patrick O.,Budagumpi, Srinivasa,Shao, Linjun
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p. 3169 - 3181
(2015/07/15)
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- Simple synthesis ofnewmixed isocyanide-nhc-platinum(ii) complexes and their catalytic activity
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Using the new modular and convergent approach to isocyanide-N-hetrocyclic carbene-platinum(II) complexes, eight new compounds have been synthesised. For three of these, detailed structural data could be obtained by X-ray crystal structure analyses. This n
- Hubbert, Christoph,Breunig, Marcus,Carroll, Kristen J.,Rominger, Frank,Hashmi, A. Stephen K.
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p. 469 - 474
(2014/04/03)
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- Platinum(II) complexes with thioether-functionalized benzimidazolin-2- ylidene ligands: Synthesis, structural characterization, and application in hydroelementation reactions
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A series of six benzimidazolium salts with an alkyl-alkyl thioether moiety in the side chain has been synthesized. While it was impossible to obtain the platinum(II) complexes by direct reaction between ligand precursors and basic platinum salts, the mild
- Bernhammer, Jan C.,Huynh, Han Vinh
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p. 172 - 180
(2014/02/14)
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- HYDROSILYLATION REACTION CURABLE COMPOSITIONS AND METHODS FOR THEIR PREPARATION AND USE
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A composition contains (A) a hydrosilylation reaction catalyst and (B) an aliphatically unsaturated compound having an average, per molecule, of one or more aliphatically unsaturated organic groups capable of undergoing hydrosilylation reaction. The composition is capable of reacting via hydrosilylation reaction to form a reaction product, such as a silane, a gum, a gel, a rubber, or a resin. Ingredient (A) contains a platinum-ligand complex that can be prepared by reacting a platinum precursor and a ligand.
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Page/Page column 46
(2013/03/26)
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- Non-precious Metal-based Hyrdosilylation Catalysts Exhibiting Improved Selectivity
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Disclosed herein is the use of manganese, iron, cobalt, or nickel complexes containing tridentate pyridine di-imine ligands as hydrosilylation catalysts. These complexes are effective for efficiently catalyzing hydrosilylation reactions, as well as offering improved selectivity and yield over existing catalyst systems.
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Paragraph 0107
(2013/06/28)
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- New organoplatinum (IV) complex with quaterpyridine ligand: Synthesis, structure and its catalytic activity in the hydrosilylation of styrene and terminal alkynes
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The reaction of ligand L with PtCl2 leads to a novel structural motif of octahedral ortho-metalated complex of formula [Pt(L-H) Cl3] 1. This result is a consequence of drastic conditions of reaction and preferred Pt(IV) octahedral coordination geometry. The new compound has been characterised on the basis of the spectroscopic data in solution, and its structure confirmed in the solid state by X-ray crystallography (1a - [Pt(L-H)Cl3]·MeOH, 1b - [Pt(L-H)Cl 3]·C6H5CH3). This article reports organoplatinum (IV) complex 1 as effective and highly selective catalyst precursor in the hydrosilylation of styrene and terminal alkynes.
- Adamski, Ariel,Kubicki, Maciej,Pawlu?, Piotr,Grabarkiewicz, Tomasz,Patroniak, Violetta
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- Iron catalysts for selective anti-Markovnikov alkene hydrosilylation using tertiary silanes
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Alkene hydrosilylation, the addition of a silicon hydride (Si-H) across a carbon-carbon double bond, is one of the largest-scale industrial applications of homogeneous catalysis and is used in the commercial production of numerous consumer goods. For decades, precious metals, principally compounds of platinum and rhodium, have been used as catalysts for this reaction class. Despite their widespread application, limitations such as high and volatile catalyst costs and competing side reactions have persisted. Here, we report that well-characterized molecular iron coordination compounds promote the selective anti-Markovnikov addition of sterically hindered, tertiary silanes to alkenes under mild conditions. These Earth-abundant base-metal catalysts, coordinated by optimized bis(imino)pyridine ligands, show promise for industrial application.
- Tondreau, Aaron M.,Atienza, Crisita Carmen Hojilla,Weller, Keith J.,Nye, Susan A.,Lewis, Kenrick M.,Delis, Johannes G. P.,Chirik, Paul J.
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scheme or table
p. 567 - 570
(2012/06/18)
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- Platinum(II)-bis-(N-heterocyclic carbene) complexes: Synthesis, structure and catalytic activity in the hydrosilylation of alkenes
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Chelating biscarbene ligands increase the stability of metal-organic catalyst systems. The catalytic activities of seven structurally different platinum(II)-bis-NHC-complexes in the hydrosilylation of alkenes have been investigated and compared with the c
- Taige, Maria A.,Ahrens, Sebastian,Strassner, Thomas
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supporting information; experimental part
p. 2918 - 2927
(2011/08/10)
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- Asymmetric hydrosilylation of alkenes with alkoxyhydrosilanes catalyzed by chiral bis(oxazolinyl)phenyl-rhodium complex
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Asymmetric addition of alkoxyhydrosilanes to styrene derivatives was examined with chiral bis(oxazolinyl)phenyl-rhodium complex to give moderate ratios (up to 77:23) of α- and β-adducts and high enantioselectivity (up to 95% for the α-adduct).
- Tsuchiya, Yasunori,Uchimura, Hirofumi,Kobayashi, Kazuki,Nishiyama, Hisao
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p. 2099 - 2102
(2007/10/03)
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- Syntheses of Organofunctional Siloxanes containing Metal-ligating Sidechains
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A range of tri-, tetra-, and penta-siloxanes of general formula Me3SiOnSiMe3 (R=vinyl, n=1-3; R=an alkyl chain terminated by the potential metal-ligating entities CH=CH2, Ph, CN, cyclohexenyl, pyridine, and PPh2, n=1 or 2) have been synthesised from commercially avilable dichlorosilanes by one of three procedures.The products are air-stable oils with the exception of the pyridine- and phosphine-functionalised compounds which react vigorously with oxygen, and the spectroscopic properties of corresponding organofunctional siloxanes are very similar showing little dependence on n.
- Brisdon, Brian J.,Watts, Andrew M.
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p. 2191 - 2194
(2007/10/02)
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