- Electrosynthese en Chimie Organosilicique: Preparation de Phenyl- et Benzyl-trimethylsilanes
-
In a single compartment cell fitted with a sacrificial magnesium anode, electrochemical reduction of phenyl and benzyl halides in the presence of trimethylchlorosilane gave the corresponding phenyl- and benzyl-silanes in satisfactory yields.Under well chosen conditions, the synthesis of phenyltrimethylsilane from phenyl bromide or chloride was also found possible.
- Pons, P.,Biran, C.,Bordeau, M.,Dunogues, J.,Sibille, S.,Perichon, J.
-
-
Read Online
- Observation of AlCL3-Catalyzed Trialkylsilylation of Benzene and Toluene with Chlorotrialkylsilanes in the Presence of Huenig Bases
-
AlCl3-catalyzed trialkylsilylation of benzene and toluene has been shown to occur using chlorotrialkylsilanes in the presence of Huenig bases.
- Olah, George A.,Bach, Thorsten,Prakash, Surya G. K.
-
-
Read Online
- Preparation method of aromatic silicon organic compound
-
The invention provides a preparation method of an aromatic silicon organic compound. The aromatic silicon organic compound is a compound as shown in a formula 3 shown in the specification, the aromatic silicon organic compound is prepared by reacting a compound as shown in a formula 1 with a compound as shown in a formula 2, and the reaction formula is as shown in the specification. In the formulas, a is selected from any integer of 0-5, n is selected from any integer of 1-6, R is selected from one of alkyl, alkoxy, fluorine, trifluoromethyl and trifluoromethoxy; m is any integer selected from 1-3, and R2 is selected from C1-C6 alkyl; a catalyst used in the reaction is MIc, MIc is iodized salt, M is metal ion, and c is selected from 1 or 2 according to the valence state of M; and magnesium is added in the reaction process. The method has the advantages of low cost, effective avoidance of heavy metal residues, simplicity and convenience in operation, high yield, mild reaction conditions and easiness in industrialization.
- -
-
Paragraph 0029-0043
(2021/07/08)
-
- Continuous-flow Si-H functionalizations of hydrosilanesviasequential organolithium reactions catalyzed by potassiumtert-butoxide
-
We herein report an atom-economic flow approach to the selective and sequential mono-, di-, and tri-functionalizations of unactivated hydrosilanesviaserial organolithium reactions catalyzed by earth-abundant metal compounds. Based on the screening of various additives, we found that catalytic potassiumtert-butoxide (t-BuOK) facilitates the rapid reaction of organolithiums with hydrosilanes. Using a flow microreactor system, various organolithiums bearing functional groups were efficiently generatedin situunder mild conditions and consecutively reacted with hydrosilanes in the presence oft-BuOK within 1 min. We also successfully conducted the di-funtionalizations of dihydrosilane by sequential organolithium reactions, extending to a gram-scale-synthesis. Finally, the combinatorial functionalizations of trihydrosilane were achieved to give every conceivable combination of tetrasubstituted organosilane libraries based on a precise reaction control using an integrated one-flow system.
- Lee, Hyune-Jea,Kwak, Changmo,Kim, Dong-Pyo,Kim, Heejin
-
supporting information
p. 1193 - 1199
(2021/02/26)
-
- Nickel-Catalyzed Decarbonylation of Acylsilanes
-
Nickel-catalyzed decarbonylation of acylsilanes is developed. In sharp contrast to cross-coupling reactions of acylsilanes, in which the silyl group serves as a leaving group, the silyl group is retained in the product in this decarbonylation reaction. Although the strong binding of the dissociated CO to the nickel center frequently hinders catalyst turnover in nickel-mediated decarbonylative reactions, this reaction can be catalyzed by nickel complexes bearing a CO ligand.
- Ito, Yuri,Kodama, Takuya,Nakatani, Syun,Sakurai, Shun,Tobisu, Mamoru
-
p. 7588 - 7594
(2020/06/27)
-
- METHOD FOR PRODUCING ARYLSILANE COMPOUND CONTAINING HALOSILANE COMPOUND AS RAW MATERIAL
-
PROBLEM TO BE SOLVED: To provide a method for producing an arylsilane compound with low production cost. SOLUTION: A method for producing an arylsilane compound includes a reaction step for the cross-coupling reaction of a halosilane compound represented by general formula (A-1), (A-2), or (A-3) and an arylboronic acid pinacol ester in the presence of a nickel catalyst, a Lewis acid catalyst, and an organic base (R independently represent an aromatic hydrocarbon group, a heteroaromatic ring group, or a C1-20 hydrocarbon group; X independently represent a halogeno group or a trifluoromethanesulfonyloxy group). SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
- -
-
Paragraph 0052-0054
(2020/03/06)
-
- Dimethylformamide-stabilised palladium nanoclusters catalysed coupling reactions of aryl halides with hydrosilanes/disilanes
-
N,N-Dimethylformamide-stabilised Pd nanocluster (NC) catalysed cross-coupling reactions of hydrosilane/disilane have been investigated. In this reaction, the coupling reaction proceeds without ligands with low catalyst loading. N,N-Dimethylacetamide is a crucial solvent in these reactions. The solvent effect was considered by various techniques, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Pd NCs can be recycled five times under both hydrosilane and disilane reaction conditions.
- Nagata, Tatsuki,Inoue, Takeru,Lin, Xianjin,Ishimoto, Shinya,Nakamichi, Seiya,Oka, Hideo,Kondo, Ryota,Suzuki, Takeyuki,Obora, Yasushi
-
p. 17425 - 17431
(2019/06/24)
-
- Nickel-Catalyzed Selective Cross-Coupling of Chlorosilanes with Organoaluminum Reagents
-
Nickel-catalyzed cross-coupling reactions of chlorosilanes with organoaluminum reagents were developed. An electron-rich Ni(0)/PCy3 complex was found to be an effective catalyst for the desired transformation. The reaction of dichlorosilanes 1 proceeded to give the corresponding monosubstituted products 2. Trichlorosilanes 4 underwent selective double substitution to furnish the corresponding monochlorosilanes 2. Overall, the selective synthesis of a series of alkylmonochlorosilanes 2 from di- and trichlorosilanes was achieved using the present catalytic systems.
- Naganawa, Yuki,Guo, Haiqing,Sakamoto, Kei,Nakajima, Yumiko
-
p. 3756 - 3759
(2019/09/12)
-
- Nickel-Catalyzed Reductive Cleavage of Carbon-Oxygen Bonds in Anisole Derivatives Using Diisopropylaminoborane
-
The catalytic removal of a methoxy group on an aromatic ring allows this group to be used as a traceless activating and directing group for aromatic functionalization reactions. Although several catalytic methods for the reductive cleavage of anisole derivatives have been reported, all are applicable only to π-extended aryl ethers, such as naphthyl and biphenyl ethers, while monocyclic aryl ethers cannot be reduced. Herein, we report a nickel-catalyzed reductive cleavage reaction of C-O bonds in aryl ethers using diisopropylaminoborane as the reducing agent. Unlike previously reported methods, this reducing reagent allows effective C-O bond reduction in a much wider range of aryl ether substrates, including monocyclic and heterocyclic ethers bearing various functional groups.
- Igarashi, Takuya,Haito, Akira,Chatani, Naoto,Tobisu, Mamoru
-
p. 7475 - 7483
(2018/07/21)
-
- Reductive Denitration of Nitroarenes
-
The Pd-catalyzed reductive denitration of nitroarenes has been achieved via a direct cleavage of the C-NO2 bonds. The catalytic conditions reported exhibit a broad substrate scope and good functional-group compatibility. Notably, the use of inexpensive propan-2-ol as a mild reductant suppresses the competitive formation of anilines, which are normally formed by other conventional reductions. Mechanistic studies have revealed that alcohols serve as efficient hydride donors in this reaction, possibly through β-hydride elimination from palladium alkoxides.
- Kashihara, Myuto,Yadav, M. Ramu,Nakao, Yoshiaki
-
supporting information
p. 1655 - 1658
(2018/03/23)
-
- Hydrocarbon-Soluble Bis(trimethylsilylmethyl)calcium and Calcium-Iodine Exchange Reactions at sp2-Hybrized Carbon Atoms
-
Hydrocarbon-soluble and highly reactive [(L)xCa(CH2SiMe3)2] (L = tetrahydropyran, x = 4 (2a); L = tmeda, x = 2 (2b)) is synthesized by the metathesis reaction of Me3SiCH2CaI (1-I) with KCH2SiMe3. The durability of 2a in tetrahydropyran solution at 0 °C is sufficiently high for subsequent chemical transformations. The reaction of ICH2SiMe3 with calcium in diethyl ether yields unique cage compound [(Et2O)2Ca(I)2·(Et2O)2Ca(I)(OEt)·(Et2O)Ca(I)(CH2SiMe3)] (3). We demonstrate that alkylcalcium complexes are valuable reagents for calcium-iodine exchange reactions at Csp2-I functionalities.
- Koch, Alexander,Wirgenings, Marino,Krieck, Sven,G?rls, Helmar,Pohnert, Georg,Westerhausen, Matthias
-
p. 3981 - 3986
(2017/10/31)
-
- Catalytic B-C Coupling by Si/B Exchange: A Versatile Route to π-Conjugated Organoborane Molecules, Oligomers, and Polymers
-
Conjugated organoboranes have emerged as attractive hybrid materials for optoelectronic applications. Herein, a highly efficient, environmentally benign catalytic B-C bond formation method is presented that uses organosilicon compounds, dibromoboranes, and the metal-free organocatalyst Me3SiNTf2. This Si/B exchange approach has been successfully applied to the synthesis of arylborane molecules 4a-c, oligomers 8a,b, and polymers 8a′,b′. Photophysical investigations, supported by TD-DFT calculations, reveal highly effective π-conjugation in thienyl- and furylborane species; the latter are also highly emissive.
- Lik, Artur,Fritze, Lars,Müller, Lars,Helten, Holger
-
supporting information
p. 5692 - 5695
(2017/05/04)
-
- Tris(trimethylsilyl)silylboronate Esters: Novel Bulky, Air- and Moisture-Stable Silylboronate Ester Reagents for Boryl Substitution and Silaboration Reactions
-
New, bulky tris(trimethylsilyl)silylboronate pinacol and hexylene glycol esters ((TMS)3Si-B(pin) and (TMS)3Si-B(hg)) were prepared in 46 and 61% yields, respectively, by the reaction of tris(trimethylsilyl)silylpotassium with the corresponding boron electrophiles. Notably, these silylboronate esters exhibited high stability to air and silica gel and were applied to the transition-metal-free boryl substitution of aryl halides, providing the desired borylated products in high yields with excellent B:Si ratios (up to 96% yield, B/Si = 99/1). These new silylboronate esters were also applied to a sequential borylation/cross-coupling process with various aryl halides, as well as the base-mediated silaboration of styrene.
- Yamamoto, Eiji,Shishido, Ryosuke,Seki, Tomohiro,Ito, Hajime
-
supporting information
p. 3019 - 3022
(2017/09/05)
-
- METHOD FOR PRODUCING ORGANIC SILANE COMPOUND AND CATALYST COMPOSITION FOR ORGANIC SILANE COMPOUND SYNTHESIS
-
PROBLEM TO BE SOLVED: To provide a production method that allows an organic silane compound to be produced efficiently and inexpensively. SOLUTION: In a method for producing an organic silane compound that makes a halogenated aryl react with a disilane or hydrosilane, a palladium element-containing nanoparticle with a solvent coordinated on its surface is employed to allow an organic silane compound to be produced efficiently and inexpensively. SELECTED DRAWING: Figure 2 COPYRIGHT: (C)2016,JPOandINPIT
- -
-
Paragraph 0037-0048
(2018/09/20)
-
- Nucleophilic attack of R-lithium at tetrahedral silicon in alkoxysilanes. An alternate mechanism
-
The currently accepted mechanism for nucleophilic attack at silicon in tetraalkoxysilanes, e.g. Si(OEt)4 is suggested to involve formation of penta- and then hexacoordinated intermediates as supported by the apparent exclusive formation of R3SiOR′ and R4Si from nucleophilic attack by RLi and RMgX. Our recent discovery of a direct route from biogenic silica to tetraalkoxyspirosiloxanes prompted us to revisit this reaction as a potential route to diverse silicon-containing species with single SiC bonds as early studies demonstrate that spirosiloxanes form quite stable pentacoordinated alkoxysilane compounds. As anticipated, Si(2-methyl-2,4-pentanediolato)2 (SP) reacts with RLi (R = Ph, anthracene, phenylacetylene, etc.) at -78 °C to form pentacoordinated Si, e.g. LiPhSP equilibrates with the starting reagents even at 3:1 ratios of PhLi:SP with no evidence for formation of hexacoordinated species by mass spectral, NMR and quenching studies. Thus, quenching with MeI or Me3SiCl allows isolation of monosubstituted products from RLi:SP; RSi(OR′)3 including some ring-opened oligomers. Comparative studies of reactions of PhLi with Si(OEt)4 allows isolation of mono- and disubstituted products again even at 1:1 ratios of PhLi:Si(OEt)4. However, on standing at -78 °C for long periods of time or on warming to 0 °C, the primary product for both reactions is Ph4Si even with 0.5 equivalents of PhLi. At reaction temperatures ≥0 °C the primary product is again Ph4Si. These results suggest that hexacoordinated intermediates are not part of the substitution mechanism and may suggest that the higher-substituted compounds arise from disproportionation processes. We also briefly describe the conversion of anthracenylSP and 9,9-dimethylfluoreneSP to silsesquioxanes.
- Furgal, Joseph C.,Laine, Richard M.
-
p. 705 - 725
(2016/07/14)
-
- Synthesis and reactions of donor cyclopropanes: efficient routes to cis- and trans-tetrahydrofurans
-
Abstract A detailed study on the synthesis and reactions of silylmethylcyclopropanes is reported. In their simplest form, these donor-only cyclopropanes undergo Lewis acid promoted reaction to give either cis- or trans-tetrahydrofurans, with the selectivity being reaction condition-dependant. The adducts themselves are demonstrated to be an important scaffold for structural diversification. The combination of a silyl-donor group in a donor-acceptor cyclopropane with novel acceptor groups is also discussed.
- Dunn, Jonathan,Dobbs, Adrian P.
-
supporting information
p. 7386 - 7414
(2015/08/24)
-
- Synthesis of heterodinuclear hemisalen complexes on a hexaarylbenzene scaffold and their application for the cross-pinacol coupling reaction
-
Intermolecular cross-pinacol coupling reaction between aliphatic and aromatic aldehydes by using heterodinuclear hemisalen complexes 1cis with vanadium(V) and titanium(IV) on a hexaarylbenzene scaffold is reported. Our ligand design is based on the individual activation of two aldehydes by vanadium and titanium, which are positioned with a suitable space on the rigid scaffold. Ligands such as 1cis were synthesized by Diels-Alder addition and decarbonylation reaction, followed by condensation of dialdehyde 3cis with various aminophenols. The influence of the substituents on the ligands on the pinacol coupling reaction was investigated. As a result, the reductive coupling reaction between aliphatic and aromatic aldehydes by using a catalytic amount of 1cis in the presence of Me3SiCl and Zn provided the corresponding cross-coupled 1,2-diol in good yields with high cross-selectivity. Working together: Dihemisalen ligands on a hexaaryl benzene scaffold were designed and the heterodinuclear complexes 1cis with vanadium(V) and titanium(IV) were synthesized from the corresponding disalicylaldehyde compound (see scheme). By using the heterodinuclear catalysts, the selective intermolecular cross-pinacol coupling reaction between aliphatic and aromatic aldehydes is demonstrated. Copyright
- Miyasaka, Akihiro,Amaya, Toru,Hirao, Toshikazu
-
p. 1615 - 1621
(2014/03/21)
-
- On the reactivity of silylboranes toward lewis bases: Heterolytic B-Si cleavage vs. adduct formation
-
Silylboranes are important reagents in a variety of catalytic silylation and silaboration reactions. While transition-metal-catalyzed reactions are well established, organo-/Lewis base-catalyzed reactions of silylboranes have only recently emerged. For both catalytic processes the reactivity of silylboranes toward Lewis bases is of relevance. While for organo-catalyzed reactions Lewis base activation of the silylborane has been proposed, transition-metal- and especially copper-catalyzed reactions also frequently require the presence of Lewis basic alkali metal alkoxides. In the present study we explore the reaction of K(18-crown-6) tert-butoxide and the NHC 1,3-diisopropyl-4,5-dimethyl- imidazol-2-ylidene as exemplary Lewis bases with the two silylboranes pinB-SiMe2Ph and pinB-SiPh3 (pin = OCMe 2CMe2O). The reaction with K(18-crown-6) tert-butoxide results in activation of the boron-silicon bond. The isolated product of this activation is either the potassium silyl complex [K(18-crown-6)SiPh3] or [K(18-crown-6)(thf)2][pinB(SiMe2Ph)2], the formal Lewis acid/base adduct of [K(18-crown-6)SiMe2Ph] with pinB-SiMe2Ph. Both complexes react essentially as sources of nucleophilic silyl moieties in reactions with exemplary electrophiles. In contrast, usage of the carbene leads to the formation of isolable Lewis acid/base adducts of the type (NHC)pinB-SiR3, which do not react as sources of nucleophilic silyl moieties. The identification and characterization of these species appears of relevance for the mechanistic understanding and further development of Lewis base/organo- as well as transition-metal-catalyzed silyl transfer reactions. Copyright
- Kleeberg, Christian,Borner, Corinna
-
supporting information
p. 2799 - 2806
(2013/07/11)
-
- Direct synthesis of alkylsilanes by platinum-catalyzed coupling of hydrosilanes and iodoalkanes
-
Alkyl iodides and tertiary silanes were successfully coupled with good functional group tolerance using a Pt(P(tBu)3)2/(iPr) 2EtN/CH3CN system. The utility of the methodology is demonstrated by the synthesis of silafluofen, a Si-containing insecticide. This journal is The Royal Society of Chemistry.
- Inubushi, Hikaru,Kondo, Hitoshi,Lesbani, Aldes,Miyachi, Mariko,Yamanoi, Yoshinori,Nishihara, Hiroshi
-
supporting information
p. 134 - 136
(2013/02/23)
-
- Near-ambient temperature halogen-lithium exchange of p-bromoanisole and related substrates: Flow/batch studies
-
With the advent of flow chemistry, the norm has been reactions executed on the laboratory scale with flow rates of only a few mL/min. We bring to the community's attention our investigation of the halogen-lithium (X-Li) exchange in a continuous flow reactor, the Synthetron. This novel reactor is capable of orders of magnitude greater rates of flow than current microreactors. This paper details a problematic X-Li exchange using our promoted hydrocarbon media formulated batch studies as well as the comparative derived flow studies. All of these studies have the additional feature of being performed at ambient or near-ambient temperatures. From the initial discoveries of Wittig and Gilman in the late 1930s, it has been known that X-Li exchange of p-bromoanisole (p-BrA) is plagued by a secondary ortho-lithiation. Fine-tuning of promoted hydrocarbon media batch studies can increase the ratio of p-LiA/o-Li-p-BrA; results from the Synthetron studies afford a much superior ratio of >100:1. Gram quantities of derivatives from this exchange (employing two reactors) can be prepared in a few seconds. Rationales for these observations will be presented as well as initial studies and discussion for bromobenzene (PhBr), m-bromoanisole (m-BrA), and p-iodoanisole (p-IA). Georg Thieme Verlag Stuttgart · New York.
- Slocum,Reinscheld, Thomask.,Austin, Nickd.,Kusmic, Damir,Whitley, Paule.
-
experimental part
p. 2531 - 2536
(2012/09/22)
-
- Palladium-catalyzed direct CH bond arylation of simple arenes with aryltrimethylsilanes
-
Direct CH bond arylation of arenes with aryltrimethylsilanes catalyzed by PdCl2 in the presence of CuCl2 as an oxidant has been developed. In addition to the role as the oxidant, CuCl2 is found to be necessary for the selective crosscoupling reaction.
- Funaki, Kenji,Kawai, Hiroshi,Sato, Tetsuo,Oi, Shuichi
-
supporting information; experimental part
p. 1050 - 1052
(2011/12/05)
-
- OPTOELECTRONIC DEVICES AND ORGANIC COMPOUNDS USED THEREIN
-
An optoelectronic device comprises a cathode; an electron-transporting layer comprising a compound of formula I; a light emitting-layer; and an anode; wherein R1 and R2 are independently at each occurrence, hydrogen, a C1-C20 aliphatic radical, a C3-C20 aromatic radical, or a C3-C20 cycloaliphatic radical; R3 is H or alkyl; a and b are, independently at each occurrence 0, or an integer ranging from 1 to 3; n is 2 or 3; and Ar is an aryl.
- -
-
-
- Halogen/lithium exchange in hydrocarbon media; Basic and continuous reactor studies
-
The halogen/lithium (X/Li) exchange's usefulness is challenged by the extreme conditions employed during the conversion of a bromo or an iodo substituent to an organolithium intermediate. Our preliminary disclosure reveals that simple X/Li exchanges can be accomplished at ambient temperature and in doped hydrocarbon media using n-BuLi. Use of a continuous reactor featuring brief reaction times (≤1 s) and large product throughputs further facilitates the production of a product resulting from a sequential X/Li exchange and nucleophilic addition.
- Slocum,Kusmic, Damir,Raber, Jeffrey C.,Reinscheld, Thomas K.,Whitley, Paul E.
-
experimental part
p. 4793 - 4796
(2010/10/02)
-
- Improved synthesis of 1,2-bis(trimethylsilyl)benzenes using Rieke-magnesium or the entrainment method
-
1,2-Bis(trimethylsilyl)benzene is the key starting material for the synthesis of efficient benzyne precursors and certain luminescent π-conjugated materials. We now report that it can be conveniently prepared in tetrahydrofuran from 1,2-dibromobenzene, chlorotrimethylsilane, and either Rieke-magnesium (MgR) or magnesium turnings in the presence of 1,2-dibromoethane as an entrainer (Mge). The most important advantages of these new protocols over the currently best-established procedure (1,2-dichlorobenzene, chlorotrimethylsilane, magnesium turnings, hexamethylphosphoramide) lie in the milder reaction conditions (MgR: 0 °C, 2 h; Mge: room temperature, 30 min vs. 100 °C, 2 days) and in the fact that the cancerogenic solvent hexamethylphosphoramide is avoided. Moreover, the improved protocols are also applicable for the high-yield synthesis of 1,2,4,5-tetrakis(trimethylsilyl)benzene, 4-fluoro-1,2- bis(trimethylsilyl)benzene, 4-chloro-1,2-bis(trimethylsilyl)benzene, and 4,5-dichloro-1,2-bis(trimethylsilyl)benzene. Copyright
- Lorbach, Andreas,Reus, Christian,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
-
experimental part
p. 3443 - 3449
(2011/02/24)
-
- Formation of silicon-carbon bonds by photochemical irradiation of (η5-C5H5)Fe(CO)2SiR3 and (η5-C5H5)Fe(CO)2Me to Obtain R3SiMe
-
Photochemical irradiation of an equimolar mixture of (η5 -C5H5)Fe(CO)2SiR3, FpSiR 3, and FpMe leads to the efficient formation of the silicon-carbon-coupled product R3SiMe, R3 = Me 3, Me2Ph, MePh2, Ph3, ClMe 2, Cl2Me, Cl3, Me2Ar (Ar = C 6H4-p-X, X = F, OMe, CF3, NMe2). Similar chemistry occurs with related germyl and stannyl complexes at slower rates, Si > Ge Sn. Substitution of an aryl hydrogen to form FpSiMe2C6H4-p-X has little effect on the rate of the reaction, whereas progressive substitution of methyl groups on silicon by Cl slows the process. Also, changing FpMe to FpCH2SiMe3 dramatically slows the reaction as does the use of (η5-C 5Me5)Fe(CO)2 derivatives. A mechanism involving the initial formation of the 16e intermediate (η5-C 5H5)Fe(CO)Me followed by oxidative addition of the Fe-Si bond accounts for the experimental results obtained.
- Fortier, Skye,Zhang, Yongqiang,Sharma, Hemant K.,Pannell, Keith H.
-
experimental part
p. 1041 - 1044
(2010/04/25)
-
- Eco-friendly hydrodehalogenation of electron-rich aryl chlorides and fluorides by photochemical reaction
-
Aryl chlorides and fluorides are smoothly hydrodehalogenated by irradiation either in neat i-PrOH or in a polar solution in the presence of hypophosphorous acid or triethylsilane. The procedure gives the halogen-free products in good to excellent yields under mild eco-friendly conditions and avoids the recourse to toxic metal catalysts.
- Dichiarante, Valentina,Fagnoni, Maurizio,Albini, Angelo
-
experimental part
p. 942 - 945
(2010/04/23)
-
- Kinetics of bromine-magnesium exchange reactions in substituted bromobenzenes
-
Competition experiments have been performed to determine the relative reactivities of substituted bromobenzenes, bromonaphthalenes, and 9-bromoanthracene toward i-PrMgCl·;LiCl in THF at 0 °C. The rates of the bromine-magnesium exchange reactions are accelerated by electron-acceptor substituents, the activating efficiency of which increases in the order para 2 = 0.83) with the proton affinities of analogously substituted aryllithiums (slope 0.8). The kinetics of two representative bromoarenes with i-PrMgCl·LiCl were found to be first-order in both bromoarene and i-PrMgCl·LiCl. Combination of the resulting second-order rate constants with the krel values from competition experiments allowed us to calculate reaction times for the bromine-magnesium exchange reactions of a large variety of bromoarenes.
- Shi, Lei,Chu, Yuanyuan,Knoechel, Paul,Mayr, Herbert
-
supporting information; experimental part
p. 2760 - 2764
(2009/08/15)
-
- Process research on the preparation of 1-(3-trimethylsilylphenyl)-2,2,2- trifluoroethanone by a friedel-crafts acylation reaction
-
Zifrosilone (1-(3-trimethylsilylphenyl)-2,2,2-trifluoroethanone) (3) is a Cholinesterase inhibitor that has been studied for the treatment of Alzheimer's disease. Process research has been carried out on a route to convert phenyltrimethylsilane to 3 by Friedel-Crafts acylation using trifluoroacetic anhydride. Kinetics and products analyses suggest that the optimal conditions for this reaction are noncatalytic amounts of aluminum chloride, dichloromethane solvent and as low a temperature as can be practically used in a scaled-up process. Significant separation challenges to isolate 3 from the isomer byproduct 1-(4-trimethykilylphenyl)-2,2,2-trifluoroethanone) (4) remain. These challenges were investigated using vapor-liquid equilibrium studies.
- Wolf, Richard A.
-
-
- Selective aromatic carbon-oxygen bond cleavage of trifluoromethoxyarenes: a trifluoromethoxy group as a convertible directing group
-
An efficient method for selective activation of aromatic C-O bonds in trifluoromethoxyarenes is developed. Upon treatment with a metallic sodium/chlorotrimethylsilane system, trifluoromethoxyarenes undergo reductive dealkoxylation to provide the corresponding arylsilanes. Also the synthetic applications of the present reactions combined with ortho-metallation are described.
- Iijima, Akinori,Amii, Hideki
-
supporting information; scheme or table
p. 6013 - 6015
(2009/04/11)
-
- Substituent effects on silene reactivity - reactive silenes from photolysis of phenylated tri- and tetrasilanes
-
Laser flash photolysis of 2-phenylheptamethyltrisilane (5d), 2,2-diphenylhexamethyltrisilane (5e), and phenyl tris(trimethylsilyl)silane (5f) in hexane and acetonitrile solution affords strong, long-lived transient absorptions centered in the 440-470 nm range, which are assigned to the transient silenes formed via [l,3]-trimethylsilyl migration into the ortho-position of a phenyl ring on the basis of their UV-vis spectra and kinetic data for their reactions with methanol (MeOH), acetic acid (AcOH), acetone, 2,3-dimethyl-1,3-butadiene (DMB), carbon tetrachloride (CCl4), and oxygen. The silene derivatives are formed along with the corresponding silylenes (SiMePh, SiPh2, and Si(SiMe3)Ph, respectively) upon photolysis of these compounds in solution, and indeed, weak, short-lived transient absorptions assignable to the silylenes can also be detected in laser photolysis experiments with the three compounds in hexane, superimposed on the much more prominent absorptions due to the silenes. The silylene absorptions are quenched by MeOH and triethylsilane (Et3SiH) with absolute rate constants varying over the narrow ranges of (1.1-1.8) x 1010 (mol/L)-1 s-1 and (2.5-3.6) × 109 (mol/L)-1 s-l, respectively, in excellent agreement with previously reported values for SiPh2 and SiMe2 under the same conditions. The kinetic data obtained for the silenes are compared to previously reported data for the reactions of the same substrates with the related silenes (6a-6c) formed by photolysis of pentamethylphenyl-, 1,1,1,2-tetramethy 1-2,2-dipheny 1-, and 1,1,1 -trimethyl-2,2,2- triphenyldisilane (5a-5c, respectively) under similar conditions. The comparison provides the first systematic, quantitative assessment of the stabilizing effects of trialkylsilyl substitution at the silenic silicon atom in silene derivatives.
- Leigh, William J.,Moiseev, Andrey G.,Coulais, Eugenie,Lollmahomed, Farahnaz,Askari, Mohammad S.
-
scheme or table
p. 1105 - 1117
(2009/03/11)
-
- Polymer supported naphthalene-catalysed sodium reactions
-
Arene-catalysed sodium reactions have been utilised in the generation of organosodium complexes, from a variety of organochloride complexes, in high yield. Phenyltrimethylsilane, benzene and 2-methyl-1-phenyl-1-propanol were prepared in yields >80%, using polymer supported naphthalene-catalysed sodium reactions, whereby phenylsodium, prepared from the reaction of chlorobenzene, sodium powder and polymer-supported naphthalene (5-100%), was quenched with chlorotrimethylsilane, water or PriCHO respectively. The Royal Society of Chemistry.
- Van Den Ancker, Tania R.,Love, Cameron J.
-
p. 3520 - 3523
(2008/09/19)
-
- Halogen-metal exchange in 1,2-dibromobenzene and the possible intermediacy of 1,2-dilithiobenzene
-
(Chemical Equation Presented) The one-step high-yield synthesis of 1,2-bis(trimethylsilyl)-benzene from 1,2-dibromobenzene using tert-butyllithium and trimethylsilyltriflate is reported. A mechanistic investigation shows that 1,2-dilithiobenzene is not an intermediate in this reaction; the coexistence of trimethylsilyltriflate and tert-butyllithium at very low temperatures allows a sequence of bromine-lithium exchange and subsequent derivatization reactions to operate.
- Bettinger, Holger F.,Filthaus, Matthias
-
p. 9750 - 9752
(2008/03/17)
-
- A highly tunable family of chiral bisphospholanes for Rh-catalyzed enantioselective hydrogenation reactions
-
A set of 16 new and closely related bisphospholane ligands have been prepared by using a highly flexible and convergent approach. Each synthesis can be performed on an industrially relevant scale. The bisphosphines differ in the nature of the bridge connecting both phospholane units. Bridges are formed by three-, four-, five- and six-membered heterocyclic or alicyclic rings. Bisphospholanes and their Rh-precatalysts have been investigated by using results of theoretical calculations (DFT) and analytic measurements ( 31P and 103Rh NMR spectroscopy, X-ray structure analysis). The studies showed that catalysts based on ligands with maleic anhydride or maleimide bridges give constantly superior enantioselectivities in methanol as the solvent. This may account for optimised steric and electronic effects. However, by changing the solvent catalysts with other backbones can give rise to excellent results. This gives proof that simple correlations between steric and electronic properties and results in the enantioselective hydrogenation frequently claimed in literature are not general.
- Holz, Jens,Zayas, Odalys,Jiao, Haijun,Baumann, Wolfgang,Spannenberg, Anke,Monsees, Axel,Riermeier, Thomas H.,Almena, Juan,Kadyrov, Renat,Boerner, Armin
-
p. 5001 - 5013
(2008/02/10)
-
- The tertiary sulfonamide as a latent directed-metalation group: Ni 0-catalyzed reductive cleavage and cross-coupling reactions of aryl sulfonamides with Grignard reagents
-
A mild method for the Ni0-catalyzed hydrodesulfamoylation (see scheme, B) of aryl sulfonamides (1→2) with iPr2Mg or iPrMgCl as β-hydride transfer sources can be linked with directed ortho metalation (A and C) to give meta-substituted aromatics 2. Cross-coupling process with alkyl and aryl Grignard reagents furnish disubstituted benzenes and bi- and teraryl compounds.
- Milburn, Robert R.,Snieckus, Victor
-
p. 888 - 891
(2007/10/03)
-
- Arylcalcium hydrides as precursors to alkoxides and aryloxides of calcium
-
Calcium atoms react with +I-substituted benzene derivatives under cocondensation conditions to yield arylcalcium hydrides. With toluene, tert-butylbenzene, and trimethyl(phenyl)silane the reaction showed no selectivity for C-H activation, resulting in the formation of each of the three possible isomers, while with m-xylene the reaction resulted in selective activation of the bond meta to the CH3 groups. Treatment of (tert-butylphenyl)calcium hydride with di- and trisubstituted phenols such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,4,6-tri-tert-butylphenol resulted in the formation of calcium aryloxides in yields > 95%. [Ca(2,4,6-tBu3C6H2O)2 (THF)3] crystallises from a THF solution as a distorted trigonal bipyramid, with two THF ligands in the trans-axial positions and the third THF ligand and both aryloxide groups in equatorial positions. The Ca-OAryl bond length was found to average at 2.181(3). A. The Ca-O-CAryl angles are almost linear, with Cal-O1-C1 and Ca1-O2-C19 being 173.9(3)° and 178.8(3)°, respectively, while the O1-Cal-O2 angle was determined as 157.04(12)°. A reaction between (tert-butylphenyl)calcium hydride and triphenylmethanol resulted in the formation of the corresponding monomeric calcium bis(alkoxide) Ca(OCPh3)2(THF)4 in 95% yield. The structure was determined as a distorted octahedron with the alkoxide ligands in a cis-equatorial arrangement. The Ca-O bond length was determined at 2.1609(17) A. The Ca-O-CAryl angle of 177.46(16)° is almost linear, while the O1-Cal-O1A angle was determined at 110.12(19)°. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Dunne, John P.,Tacke, Matthias,Selinka, Carola,Stalke, Dietmar
-
p. 1416 - 1425
(2007/10/03)
-
- Reactions of trimethylstannide and trimethylsiliconide anions with aromatic and heteroarornatic substrates
-
A parallel study was carried out on the reactions of Me3Sn- and Me3Si- ions towards aromatic and heteroaromatic substrates in hexamethylphosphoramide (HMPA) as solvent. It was found that Me3Si- ions are more reactive and therefore less selective than Me3Sn- ions. In HMPA, PhI and PhBr react with Me3Sn- ions through an HME pathway. PhCl also reacts by an HME reaction, but under photostimulation the SRN1 mechanism competes with the HME process, With PhF as sabstrate, Me3Sn- ions afford (4-fluorophenyl)trimethylstannane, presumably through a hypervalent tin species. Under irradiation, the SRN1 mechanism operates concurrently with the formation of the hypervalent tin species. Me3Si- ions, on the other hand, react with PhX (X = Cl, Br, I) to yield the ipso substitution product, presumably through the intermediacy of a hypervalent silicon species. PhF affords, upon reaction with Me3Si- ions, o- and p-fluorotrimethylsilylbenzenes together with the ipso substitution product PhSiMe3. A novel type of nucleophilic substitution mechanism takes place with Me3Si- ions upon reaction with aromatic and heteroaromatic substrates without classical leaving groups in HMPA. Copyright
- Postigo, Al,Vaillard, Santiago E.,Rossi, Roberto A.
-
p. 889 - 893
(2007/10/03)
-
- A novel type of nucleophilic substitution reactions on nonactivated aromatic compounds and benzene itself with trimethylsiliconide anions.
-
[reaction: see text]. The reaction of fluorobenzene with Me3Si- anion (1) in HMPA at room temperature surprisingly affords o- and p-fluorotrimethylsilylbenzenes (substitution of aromatic H for TMS, 76% yield) 7a and 7b and also 14% of trimethylsilylbenzene (2). Benzene itself reacts at 50 degrees C to furnish 4 in 45% yield. Pyridine affords p-trimethylsilylpyridine quantitatively. Mechanistic studies are presented.
- Postigo,Rossi
-
p. 1197 - 1200
(2007/10/03)
-
- Diphenylphosphinophenolate: A ligand for the palladium-catalysed silylation of aryl halides activating simultaneously both palladium and silicon
-
Diphenylphosphinophenolate was found to be an effective ligand for the palladium-catalysed silylation of aryl halides, activating not only palladium but also silicon of a disilane, where aryl bromides and iodides having such substituents as methyl, methoxy, amino, ethoxycarbonyl, trifluoromethyl, formyl or phenyl are applicable to the reaction with hexamethyldisilane to give the corresponding trimethylsilylarenes.
- Shirakawa,Kurahashi,Yoshida,Hiyama
-
p. 1895 - 1896
(2007/10/03)
-
- Arene-catalysed lithiation of fluoroarenes
-
The reaction of different fluoroarenes 1 with lithium and a catalytic amount (7%) of naphthalene in THF at -30°C affords the corresponding aryllithium intermediates which, by reaction with several electrophiles at temperatures ranging between -30 and 0°C, lead to the expected products 2, after hydrolysis. (C) 2000 Elsevier Science Ltd.
- Guijarro, David,Yus, Miguel
-
p. 1135 - 1138
(2007/10/03)
-
- Reactions of organolanthanide compounds RLnI (Ln = Yb, Eu, Sm) with organic derivatives of silicon, tin, lead, and antimony
-
Reactions of compounds RLnI (R = Alk, Ar; Ln = Yb, Eu, Sm) with hexaalkyl(aryl)-distannanes, trimethylsilyltriphenyltin, and lead and antimony acetates were studied. The reactions with Sn-Sn and Si-Sn organic derivatives result in cleavage of Sn-Sn amd Sn-Si bonds with formation of tetrasubstituted stannanes and reactive organometallic derivatives with an Sn-Ln or Si-Ln bond. The reactions of RYbI with lead and antimony acetates and with tetraethoxysilane cause cleavage of the Pb-O, Sb-O, or Si-O bond with formation of tetrasubstituted derivatives of lead and silicon or trisubstituted antimony derivatives.
- Rybakova,Syutkina,Petrov
-
p. 244 - 246
(2007/10/03)
-
- A mild and efficient protocol for the catalytic silylation of aryl bromides
-
New catalyst systems were developed which facilitate palladium-catalyzed silylation of various functionalized aryl and heteroaryl bromides with hexamethyldisilane under unprecedented mild conditions. The use of two different sets of ligands and bases for electron-rich and electron-poor substrates, respectively, is crucial for achieving excellent product selectivities at 100 °C and atmospheric pressure. For electron-rich substrates, diphenyl-2'-pyridylphosphine in combination with K2CO3 gives the best results, whereas for electron-poor substrates, 2-(di-t-butylphosphino)biphenyl/KF is preferred. Even base-sensitive arylsilanes, which are inaccessible by the traditional routes via organolithium species or Grignard reagents, can be prepared in a single step and high yields.
- Goossen,Ferwanah
-
p. 1801 - 1803
(2007/10/03)
-
- Mixed reagent (aminosilyl)lithium/i-PrMgBr for the synthesis of functionalized oligosilanes
-
Mixed reagents prepared in situ from the (aminosilyl)lithiums with i-PrMgBr undergo coupling reactions with chloro-oligosilanes without Si-Si bond cleavage, which is a serious side reaction with the (aminosilyl)lithiums themselves. Based on the coupling reaction and the amino-to-chloro transformation, functionalized tetrasilanes and hexasilanes are synthesized. The analysis of the 1H- and 29Si-NMR spectra indicates that these oligosilanes include three configurational isomers, ll, ul, and uu.
- Kawachi, Atsushi,Tamao, Kohei
-
p. 259 - 266
(2007/10/03)
-
- Arene catalysed sodium reactions
-
2-Methyl-1-phenylpropan-1-ol and phenyltrimethylsilane were prepared in yields >85%, using naphthalene catalysed sodium reactions, whereby phenylsodium, prepared from the reaction of chlorobenzene, sodium powder and naphthalene (5%), was quenched with iso
- Van Den Ancker, Tania R.,Hodgson, Margaret J.
-
p. 2869 - 2870
(2007/10/03)
-
- Polymer and metal oxide supported alkali metal naphthalenides: Application in the generation of lithium and sodium reagents
-
Highly coloured paramagnetic polymer supported lithium 5,5′ and sodium 6,6′ naphthalenide complexes have been prepared from the reaction of THF solutions of lithium and sodium biphenylide with polystyrene bearing -CH2SiMe2(C10H7) groups. Treating chloropropyl functionalised silica, alumina and titania surfaces with H3Al · NMe3 or H3Ga · NMe3 afford hydroxyl depleted surfaces. Successive treatment with lithium biphenylide, 1-(chlorodimethylsilyl)naphthalene and an alkali biphenylide affords supported alkali naphthalenide complexes which generate in high yield lithium and sodium reagents when treated with a range of organic halides, nitriles and phosphates, as found for 6,6′ and 7,7′.
- Van Den Ancker, Tania R.,Raston, Colin L.
-
p. 283 - 300
(2007/10/03)
-
- Kinetic Control in the Cleavage of Unsymmetrical Disilanes
-
A series of 12 phenyl-substituted arylpentamethyldisilanes 1a-1 have been synthesized in order to examine the regioselectivity of their nucleophilic Si,Si bond cleavage reactions under Still's conditions (MeLi/HMPA/0°C). It has been found that the sensitivity of these reactions to the electronic effects of the substituents in the phenyl ring could be described by the Hammett-type equation log(kA/kB) = 0.4334 + 2.421(Σσ); (correlation coefficient R = 0.983). The kA/kB ratio represents the relative rate of attack at silicon atom A (linked to the aryl ring) or at silicon atom B (away from the aryl ring) of the unsymmetrical disilanes. Thus, the present investigation shows that the earlier belief according to which the nucleophilic cleavage of unsymmetrical disilanes always produces the more stable silyl anionic species (thermodynamic control) should be abandoned, or at least seriously amended: kinetic factors appear to exert a primary influence on the regioselectivity of such reactions. Since the two major kinetic factors (i.e., electrophilic character of and steric hindrance at a given silicon atom) have opposite effects on the orientation of the reaction, it may happen that kinetic and thermodynamic control lead to the same result. For some of the unsymmetrical disilanes studied, the major reaction path was not the Si,Si bond cleavage; instead, Si-aryl bond breaking occurred, producing the corresponding aryl anions.
- Hevesi, Laszlo,Dehon, Michael,Crutzen, Raphael,Lazarescu-Grigore, Adriana
-
p. 2011 - 2017
(2007/10/03)
-
- Nickel-catalysed Substitutions of Aryl tert-Butyl Sulfones with Organometallic Reagents: Synthesis of ortho-Substituted Unsymmetrical Biaryls
-
In the presence of a catalytic amount of a nickel salt, aryl tert-butyl sulfones react with aryl Grignard reagents to give biaryls.This reaction is used in conjunction with the powerful ortho-lithiation-directing ability of aryl tert-butyl sulfonyl groups to make unsymmetrical ortho-substituted biaryls.In certain cases, the substitution of an aryl alkylsulfonyl group by an organometallic reagent is possible without a transition metal catalyst.
- Clayden, Jonathan,Cooney, J. Jonathan A.,Julia, Marc
-
-
- Addition of organocopper reagents to allylic acrylates - The preparation of γ, δ-unsaturated acids and subsequent functionalization to γ-lactones
-
Conjugate addition of monoorganocopper compounds with iodotrimethylsilane (TMSI) or lithium diorganocuprates, with or without halosilanes, to allylic acrylates give allylic silyl ketene acetals/ester enolates. These can undergo Claisen rearrangement to give diastereomeric mixtures of γ, δ-unsaturated acids after aqueous work-up. For organocuprates, the diastereomeric ratio is strongly affected by the halosilane. Either diastereomer can be obtained as major product by proper choice of copper reagent. Cyclization of the acids followed by reduction gives γ-lactones in good yields. A copper iodide/dimethyl sulfide complex is introduced as an excellent precursor to organocopper reagents.
- Eriksson, Magnus,Hjelmencrantz, Anders,Nilsson, Martin,Olsson, Thomas
-
p. 12631 - 12644
(2007/10/02)
-
- Organolithium reagents by reductive decyanation of nitriles with lithium and a catalytic amount of 4,4'-di-tert-butyl-biphenyl in a Barbier-type reaction
-
The reaction of different nitriles 1 with an excess of lithium powder (1:14 molar ratio) and a catalytic amount of 4,4'-di-tert-butylbiphenyl (5 mol %) in the presence of a carbonyl compound (Barbier-type conditions) in THF at low temperature (-30 or -78°C) leads to the corresponding compounds 2 resulting from the coupling between the electrophile and the organolithium intermediate arising from a reductive decyanation of the starting nitrile 1. This new reaction can be also applied to the use of trimethylchlorosilane as electrophile at 0°C.
- Guijarro,Yus
-
p. 3447 - 3452
(2007/10/02)
-
- o-Trimethylsilylphenyllithium as a synthetic equivalent of o-halophenyllithium
-
The reaction of o-trimethylsilylphenyllithium with carbonyl compounds and subsequent halogenodesilylation with ICl afforded o-iodophenylcarbinols in good yields, showing the usefulness of o-trimethylsilylphenyllithium as a synthetic equivalent of o-iodophenyl anion. The reaction via a protected o-trimethylsilylphenylcarbinol is also shown.
- Takahashi, Masaki,Hatano, Ken,Kimura, Mikio,Watanabe, Toshinari,Oriyama, Takeshi,Koga, Gen
-
p. 579 - 582
(2007/10/02)
-
- Direct Transformation of Trialkyl Phosphates into Organolithium Compounds by a DTBB-Catalysed Lithiation
-
The reaction of different alkylic or phenylic phosphates 1 with an excess of lithium powder and a catalytic amount of DTBB (5 mol percent) in the presence of an electrophile -Barbier-type reaction conditions- in THF at -30 deg C leads to the formation of the expected products 2, resulting from the reaction of the in situ generated organolithium compound with the corresponding electrophile.
- Guijarro, David,Mancheno, Balbino,Yus, Miguel
-
p. 8551 - 8558
(2007/10/02)
-
- Peculiarities in the cleavage by methyllithium of unsymmetrical disilanes
-
The title reactions did not produce the more stable silyl anions from the disilanes studied, they either occurred by attack at the more electrophilic silicon atom, or led to unexpected products.
- Hevesi,Dehon
-
p. 8031 - 8032
(2007/10/02)
-
- ortho-Substituted Unsymmetrical Biaryls from Aryl tert-Butyl Sulfones
-
Nickel-catalysed coupling of arylmagnesium halides with aryl tert-butyl sulfones, and in particular with those bearing ortho-substituents introduced by ortholithiation, gives ortho-substituted unsymmetrical biaryls.
- Clayden, Jonathan,Julia, Marc
-
p. 1682 - 1683
(2007/10/02)
-