- Stable -ESiMe3 Complexes of CuI and AgI (E=S, Se) with NHCs: Synthons in Ternary Nanocluster Assembly
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As a part of efforts to prepare new "metallachalcogenolate" precursors and develop their chemistry for the formation of ternary mixed-metal chalcogenide nanoclusters, two sets of thermally stable, N-heterocyclic carbene metal-chalcogenolate complexes of the general formula [(IPr)Ag-ESiMe3] (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; E=S, 1; Se, 2) and [(iPr2-bimy)Cu-ESiMe3]2 (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene; E=S, 4; Se, 5) are reported. These are prepared from the reaction between the corresponding carbene metal acetate, [(IPr)AgOAc] and [(iPr-bimy)CuOAc] respectively, and E(SiMe3)2 at low temperature. The reaction of [(IPr)Ag-ESiMe3] 1 with mercury(II) acetate affords the heterometallic complex [{(IPr)AgS}2Hg] 3 containing two (IPr)Ag-S- fragments bonded to a central HgII, representing a mixed mercury-silver sulfide complex. The reaction of [(iPr2-bimy)Cu-SSiMe3]2, which contains a smaller N-heterocyclic-carbene, with mercuric(II) acetate affords the high nuclearity cluster, [(iPr2-bimy)6Cu10S8Hg3] 6. The new N-heterocyclic carbene metal-chalcogenolate complexes 1, 2, 4, 5 and the ternary mixed-metal chalcogenolate complex 3 and cluster 6 have been characterized by multinuclear NMR spectroscopy (1H and 13C), elemental analysis and single-crystal X-ray diffraction.
- Azizpoor Fard, Mahmood,Levchenko, Tetyana I.,Cadogan, Carolyn,Humenny, William J.,Corrigan, John F.
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- Development of mono- and Di-AcO substituted BODIPYs on the boron center
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Mono- and di-AcO substituted BODIPYs (1 and 2) were synthesized from TM-BDP. The structures of 1 and 2 were supported by single crystal X-ray analysis. Both 1 and 2 possess a large absorption coefficient, high fluorescence quantum yield, and high light stability. Compound 2 has much improved water solubility which is highly desirable for biological applications. Theoretical calculation supports our observations in X-ray analysis, absorption, and cyclic voltammetry.
- Jiang, Xin-Dong,Zhang, Jian,Furuyama, Taniyuki,Zhao, Weili
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Read Online
- A New Entry to p-Allylcobalt Tricarbonyls Using (CH3)3SiCo(CO)4
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The reactions of (CH3)3SiCo(CO)4 with allyl acetates, enones, and a diene monoepoxide gave corresponding pi-allylcobalt tricarbonyls.
- Chatani, Naoto,Yamasaki, Yasuhiro,Murai, Shinji,Sonoda, Noboru
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- Te(II)/Te(IV) Mediated C-N Bond Formation on 2,5-Diphenyltellurophene and a Reassignment of the Product from the Reaction of PhI(OAc)2 with 2 TMS-OTf
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We report a novel C-H to C-N bond metathesis at the 3-position of 1,2-diphenyltellurophene via oxidation of the Te(II) center to Te(IV) using the I(III) oxidant [PhI(4-DMAP)2]2+. Spontaneous reduction of a transient Te(IV) coordination compound to Te(II) generates an electrophilic equivalent of 4-DMAP that substitutes at a C-H bond at the 3-position of the tellurophene. Theoretical and synthetic reaction pathway studies confirm that a Te(IV) coordination complex with 4-DMAP is an intermediate. In the course of these pathway studies, it was also found that the identity of the I(III) oxidant generated from PhI(OAc)2 and 2 TMS-OTf is PhI(OAc)(OTf) and not PhI(OTf)2, as had been previously thought. (Figure Presented).
- Aprile, Antonino,Iversen, Kalon J.,Wilson, David J. D.,Dutton, Jason L.
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Read Online
- Trimethylsilyl Esters as Novel Dual-Purpose Protecting Reagents
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Trimethylsilyl esters, AcOTMS, BzOTMS, TCAOTMS, etc., are inexpensive and chemically stable reagents that pose a negligible environmental hazard. Such compounds prove to serve as efficient dualpurpose reagents to respectively achieve acylation and trimethylsilylation of alcohols under acidic or basic conditions. Herein, a detailed study on protection of various substrates and new methodological investigations is described.
- Chen, Jyun-Siao,Huang, Po-Hsun,Hsieh, Ya-Chi,Liu, Jen-Wei,Hsu, Hsiao-Lin,Zhang, Kai-Min,Wu, Ren-Tsung,Chang, Ting-Shuo,Liu, Yu-Hao,Wu, Hsin-Ru,Luo, Shun-Yuan
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supporting information
p. 754 - 762
(2021/12/02)
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- Production of acyloxysilane
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[A] a method for producing functional chemicals useful as efficient acyloxysilane. The silanol Si-to-OH bond [a], in the presence of a catalyst, comprising the step of reacting a carboxylic acid anhydride, Si-to-OCO bond (OCO is, oxycarbonyl groups (=O) O-a C shown. ) Having an acyloxysilane manufacturing method, wherein the catalyst, or (2) (1) production of acid catalyst selected from the next acyloxysilane. (1) 3 - 15 Of the periodic table of the first group the first group element selected from the perchlorate salt, trifluoromethanesulfonic acid salt, a bis (trifluoromethanesulfonyl imide) salt, lithium hexafluorophosphate salt, chloride, or bromide; inorganic acids; or an organic acid. (2) Inorganic or organic solid acid compounds[Drawing] no
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Paragraph 0059-0064
(2021/10/30)
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- Copper-Catalyzed Radical 1,4-Difunctionalization of 1,3-Enynes with Alkyl Diacyl Peroxides and N-Fluorobenzenesulfonimide
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Many reactions involving allenyl ion species have been studied, but reactions involving allenyl radicals are less well understood, perhaps because of the inconvenience associated with the generation of short-lived allenyl radicals. We describe here a versatile method for the generation of allenyl radicals and their previously unreported applications in the intermolecular 1,4-carbocyanation and 1,4-sulfimidocyanation of 1,3-enynes. With the assistance of the trifunctional reagents, alkyl diacyl peroxides or N-fluorobenzenesulfonimide, a range of synthetically challenging multisubstituted allenes can be prepared with high regioselectivity. These multisubstituted allenes can be easily transformed into synthetically useful structures such as fluorinated vinyl cyanides, lactones, functionalized allenyl amides, 1-aminonaphthalenes, and pyridin-2(1H)-ones, and several novel transformations are reported. The results of radical scavenger and radical clock experiments are consistent with the proposed allenyl radical pathway. Density functional theory (DFT) and IR spectroscopy studies suggest the formation of an isocyanocopper(II) species in the ligand exchange step. On the basis of the results of IR, DFT, and diastereoselectivity studies, an isocyanocopper(II)/copper(I) catalytic cycle is proposed, which differs from the previously considered Cu(III) mechanism in cyanation reactions.
- Zhu, Xiaotao,Deng, Weili,Chiou, Mong-Feng,Ye, Changqing,Jian, Wujun,Zeng, Yuehua,Jiao, Yihang,Ge, Liang,Li, Yajun,Zhang, Xinhao,Bao, Hongli
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p. 548 - 559
(2019/01/04)
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- Palladium-Catalyzed Regioselective Synthesis of 1-Benzoazepine Carbonitriles from o-Alkynylanilines via 7-endo-dig Annulation and Cyanation
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We herein report a three-component, one-pot cascade reaction involving an imination/annulation/cyanation sequence for the synthesis of 1-benzoazepine carbonitrile derivatives using readily available o-alkynylanilines, cyclic ketones and trimethylsilyl cyanide. This regio- and stereoselective reaction was achieved by combining palladium(II) trifluoroacetate and copper(II) acetate in dimethyl sulfoxide. The important features of this method include a broad substrate scope, the use of trimethylsilyl cyanide as a cyanating agent, the formation of two C?C bonds and one C?N bond, mild reaction conditions and good product yields. (Figure presented.).
- Dhandabani, Ganesh Kumar,Mutra, Mohana Reddy,Wang, Jeh-Jeng
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p. 4754 - 4763
(2018/11/10)
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- Method for Producing Acyloxysilanes, Acyloxysilanes Obtained Thereby, and Use of Same
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An object of the invention is to provide a method for efficiently producing an acyloxysilane which is useful as a functional chemical, an acyloxysilane obtained thereby, and the use thereof. The present invention provides: a method for producing an acyloxysilane, including a reaction step of reacting an alkoxysilane with a carboxylic anhydride in the presence of a catalyst, wherein the alkoxysilane is a specified alkoxysilane represented by General Formula (I), the carboxylic anhydride is a specified carboxylic acid represented by General Formula (IIA) or (IIB), the catalyst is an acid catalyst, and an acyloxysilane obtained in the reaction step is a specified acyloxysilane represented by General Formula (IIIA) or (IIIB); and the use of the acyloxysilane as a surface treatment agent or the like.
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Paragraph 0130; 0131
(2018/03/25)
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- Sysntehsis of trimethylacetoxysilane
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The invention relates to synthesis of sysntehsis of trimethylacetoxysilane. Synthesis of the trimethylacetoxysilane includes the steps that 120 g of glacial acetic acid is added into a 500 mL three-mouth bottle equipped with a nitrogen gas inlet, a thermometer and a magnetic stirring and low-temperature condensing pipe (-10 DEG C), and the temperature is raised to 110-130 DEG C; under the conditions of stirring and introduction of nitrogen gas, 217 g of trimethylchlorosilane is dropwise added into a reaction bottle with a constant-pressure funnel after 2-4 hours, and HCl gas discharged through a reaction is absorbed as a NaOH solution; after the trimethylchlorosilane is completely dropwise added, stirring is continued, blowing and washing are performed with the nitrogen gas for one hour; and cooling is performed till the room temperature is reached, then 6 g of potassium acetate is added into the reaction bottle in three separate times, stirring is performed by 1-3 hours, and it is tested that the chlorosilane is completely converted. 222 g of the synthesis of trimethylacetoxysilane is obtained through reaction liquid filtering and filter liquid reduced pressure distillation, and the yield is 84%.
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Paragraph 0005; 0006; 0007; 0008; 0009; 0010
(2017/08/28)
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- Preparation method of trimethylacetoxysilane
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The invention relates to a preparation method of trimethylacetoxysilane. The preparation method is characterized by comprising the following steps of adding 120g of glacial acetic acid into a 500mL three-necked flask which is provided with a nitrogen inlet, a thermometer, a magnetic stirrer and a low-temperature condensation tube and has a temperature of -10 DEG C; conducting heating to 110-130 DEG C; dropwise adding 217g of trimethyl chlorosilane into the reaction flask by virtue of a constant-pressure hopper within 2-4 hours under conditions of stirring and introducing nitrogen, wherein the HCl gas released by the reaction is absorbed by use of a NaOH solution; after dropwise adding trimethyl chlorosilane, further conducting stirring and performing blow washing with nitrogen gas for 1-3 hours; after cooling to the room temperature, adding 6g of potassium acetate into the reaction flask in three times, and performing stirring for 1-3 hours, wherein, through detecting, chlorsilane is completely converted; and filtering a reaction liquid, and performing reduced-pressure distillation on the filtrate, thereby obtaining trimethylacetoxysilane.
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Paragraph 0005; 0006; 0007; 0008; 0009; 0010; 0011
(2017/04/28)
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- METHOD OF PRODUCING A HYDROLYZABLE SILICON-CONTAINING COMPOUND
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The present invention provides a safe, inexpensive, and high yield means of producing a hydrolyzable silicon-containing compound, e.g., an organooxysilane and the like. A compound (A) represented by the general formula R1-O-R2 wherein R1 represents a C4-30, substituted or unsubstituted, tertiary alkyl group or aralkyl group and R2 represents a C1-30, substituted or unsubstituted, monovalent hydrocarbyl group or acyl group, is reacted in the presence of a Lewis acid catalyst with a halosilane (B) represented by the general formula R3mSiX4-m wherein R3 represents the hydrogen atom or a C1-30 substituted or unsubstituted monovalent hydrocarbyl group, X is independently bromine or chlorine, and m represents an integer from 0 to 3.
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Page/Page column 18; 20
(2012/07/14)
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- PROCESS FOR SILYLATING MONOCARBOXYLIC ACIDS
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A process for preparing silylated monocarboxylic acids by reacting C2-C10-monocarboxylic acids with halosilanes of the general formula (I) SiHal4-xRx??(I) in which Hal is a halogen atom selected from the group of fluorine, chlorine, bromine and iodine, R is independently hydrogen, Cl-C10-alkyl or aryl and x is an integer of 0 to 3 to form hydrogen halide in the presence of an auxiliary base, wherein the auxiliary base and the hydrogen halide form a salt which forms two immiscible phases with the product of value or the solution of the product of value in a suitable solvent and is removed.
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Page/Page column 4
(2010/06/22)
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- Semisynthesis and pharmacological activities of Tetrac analogs: Angiogenesis modulators
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Novel Tetrac analogs were synthesized and then tested. Anti-angiogenesis efficacy was carried out using the Chick Chorioallantoic Membrane (CAM) model and the mouse matrigel model for angiogenesis. Pharmacological activities showed Tetrac can accommodate numerous modifications and maintain anti-angiogenesis activity.
- Bridoux, Alexandre,Cui, Huadong,Dyskin, Evgeny,Yalcin, Murat,Mousa, Shaker A.
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experimental part
p. 3259 - 3263
(2010/04/05)
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- Asymmetric conjugate addition of azide to α,β-unsaturated nitro compounds catalyzed by cinchona alkaloids
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The cinchona alkaloid catalyzed asymmetric addition of azide to α,β-unsaturated nitro compounds giving optically active β-azido nitro compounds in high yields and with low enantioselectivity is presented. Subsequent modifications allow for the formation of chiral 1,2-diamines.
- Nielsen, Martin,Zhuang, Wei,J?rgensen, Karl Anker
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p. 5849 - 5854
(2008/02/03)
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- Process for the preparation of acyloxysilanes
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Process for the preparation of acyloxysilane comprising the step of reacting, in the presence of a strong acid, a hexahydrocarbyldisiloxane with a carboxylic anhydride.
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- A study on the haterogeneous reaction of trialkylsilyl chlorides with inorganic salts and monocarboxylates catalysed by PEG400
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The important and useful trialkylsilyl pseudohalides R3SiX, where X=NCS, NCO, N3 or CN and R=methyl or ethyl, and trimethylsilyl monocarboxylates, where X=RCOO, were readily prepared in high yields by nucleophilic substitution of R3SiCl with X ions provided by NaX or KX at room temperature catalysed by PEG400 and zinc iodide. The reactions of trimethylsilyl chloride with some metal oxysalts were also studied for the first time.
- Du, Yun-Fei,Cao, Yu-Qing,Dai, Zhi,Chen, Bao-Hua
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p. 223 - 225
(2007/10/03)
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- Thermolysis of alkoxyaluminum and siloxyaluminum acylates
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Thermolysis of alkoxyaluminum acylates (RO)nAl(OCORt)3-n (n = 1, 2; R = i-Pr, s-Bu, t-Bu, Rt = Ph, CH2I; R = PhCH2, Rt = Me, Et, Ph; R = Me3Si, Et3Si, Rt = Me) was studied. The main direction of thermolysis of derivatives of primary and secondary alcohols and of unsubstituted carboxylic acids is ester and alcohol formation. Trialkylsiloxyaluminum acylates termolyze to give in the first stage no other products than trialkylacyloxysilanes. Thermolysis of iodoacylates (RO)2AlOCOCH2I (R = Pr, s-Bu) involves oxidation of the alkoxy group to carbonyl compounds with simultaneous formation of a ketene and hydrogen iodide. tert-Butoxyaluminum acylates regardless of the structure of substituent in the acyloxy group undergo symmetrization to aluminum tert-butylate.
- Stepovik,Kazakina,Martynova
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p. 1371 - 1377
(2007/10/03)
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- Amine-catalyzed addition of azide ion to α,β-unsaturated carbonyl compounds
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(matrix presented) A new protocol for the β-azidation of α,β-unsaturated carbonyl compounds is described. The method employs tertiary amines as catalysts for azide addition. The azide source is a 1:1 mixture of TMSN3 and AcOH. Tertiary amines, either in solution or bound to a solid support, are efficient catalysts for the reaction.
- Guerin, David J.,Horstmann, Thomas E.,Miller, Scott J.
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p. 1107 - 1109
(2008/02/09)
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- Preparation of acyloxysilanes
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Acyloxysilanes are prepared by the anhydrous reaction of stoichiometric amounts of a carboxylic acid with a mixture of a halosilane and a silazane in an aprotic solvent, such as diethyl ether, acetonitrile, tetrahydrofuran or toluene, in an inert gas atmosphere. In a preferred embodiment the silazane is prepared in situ by the reaction of the corresponding halosilane and ammonia. No catalyst is necessary and the reaction preferably is performed at a temperature of -5° C. to 45° C.
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- Iodine and its interhalogen compounds: Versatile reagents in carbohydrate chemistry v. synthesis of 1,2-trans-linked 1-thioglycosides from the per-o-acetylated glycoses
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Treatment of per-O-acetylated mono- and di-saccharides with (alkyl/arylthio)trimethylsilane and iodine at ambient temperature results in the formation of the corresponding 1,2-trans-1-thioglycosides in very high yield. In the case of higher boiling thiols such as ethanethiol, the reaction can be effectively carried out in the presence of the thiol itself instead of the silylated derivative, but the reaction is not stereospecific. Moreover, in the latter reactions a portion of the starting material remains unchanged even on prolonged reaction. With β-D-glucose pentaacetate (11) as the starting material, its epimerisation occurred during the reaction and therefore the recovered starting material was of α-D-configuration. In addition, the methyl disulphide-hexamethyldisilane system has been found to serve as an effective and cheaper alternative to the expensive (methylthio)-trimethylsilane.
- Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 693 - 702
(2007/10/03)
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- Reactivity of Tris(trimethylsilyl) Borate
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Reactions of tris(trimethylsilyl) borate with water (on heating), sulfuric acid, and acetic anhydride yield boric acid, bis(trimethylsilyl) sulfate, and acetoxytrimethylsilane, respectively.
- Voronkov,Roman,Maletina
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p. 1047 - 1048
(2007/10/03)
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- Silylation of Allylic Trifluoroacetates and Acetates Using Organodisilanes Catalyzed by Palladium Complex
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Silylation of allylic acetates (1) using organodisilanes (2) was carried out in the presence of a catalytic amount of Pd(DBA)2-LiCl at 100 deg C. The silylation proceeded smoothly without β-hydrogen elimination of a resulting (?-allyl)palladium intermediate. The added chloride salt such as LiCl or NaCl was indispensable for the catalytic activity. On the other hand, remarkable improvement of the silylation was realized by employing allylic trifluoroacetates (4) in place of the acetates (1) as the substrates. The silylation proceeded even at room temperature, and the added chloride salts was not necessary as the catalyst component. In the silylation, transmetalation of the disilanes (2) with (η3-allyl)palladium intermediate (7) might be a critical step in the catalytic cycle. Model reactions for the transmetalation were carried out.
- Tsuji, Yasushi,Funato, Masahiro,Ozawa, Masakatsu,Ogiyama, Hiroaki,Kajita, Satoshi,Kawamura, Takashi
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p. 5779 - 5787
(2007/10/03)
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- Synthesis and Thermolysis of Ketal Derivatives of 3-Hydroxy-1,2-dioxolanes
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3--3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (2), 3-methoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (3), and 3-acetoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (4) were synthesized from the corresponding 3-hydroxy-1,2-dioxolane (1a) under basic conditions. 3-Acetoxy-4,4-dimethyl-3,5,5-triphenyl-1,2-dioxolane (5) was also synthesized via this approach.Under acidic conditions, 3-hydroxy-1,2-dioxolane 1a underwent quantitative decomposition to phenol and 3,3-dimethyl-2,4-pentanedione.This competing degradation was dependent on the nature of the substituents at position-5.Methyl groups at position-5 slowed the degradative rearrangement whereas phenyl groups favored it. 3-Methoxy- and 3-(allyloxy)-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolanes (6, 7) were synthesized under acidic conditions from the appropriate 1,2-dioxolane precursors and the corresponding alcohols.At 60 deg C, derivatized 1,2-dioxolanes 2-7 were found to be more stable than the corresponding 3-hydroxy-1,2-dioxolanes.The first order rate constants for the thermolysis of 1,2-dioxolanes 2-7 were determined.Product studies showed that thermolysis of 2-5 yielded pairs of ketones and derivatized carboxylic acids.In addition to R-group migration products, an acetoxy migration product was observed for the thermolysis of 4.Thermolysis of 6 at 60 deg C in benzene yielded methyl benzoate and pinacolone, quantitatively.Thermolysis of 7 yielded products analogous to those for 6.No evidence for internal trapping of radicals by the carbon-carbon double bond of the allyloxy group in 7 was found.The thermolysis appeared to proceed with peroxy bond homolysis as the rate-determining step.Subsequent β-scissions of the intermediate 1,5-oxygen diradical with interesting rearrangements that show a high preference for alkyl vs phenyl migration account for the observed product distributions.The results suggest that the β-scission/rearrangement mechanism may not be concerted but rather stepwise to yield 1,3-diradical and carbonyl fragments.
- Baumstark, A. L.,Vasquez, P. C.,Chen, Y.-X.
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p. 6692 - 6696
(2007/10/02)
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- Cyanation of Allylic Carbonates and Acetates Using Trimethylsilyl Cyanide Catalyzed by Palladium Complex
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Allylic carbonates and acetates are cyanated with trimethylsilyl cyanide in the presence of a catalytic amount (5 mol percent based on the allylic substrates) od Pd(PPh3)4 or Pd(CO)(PPh3)3 in THF under reflux to afford β,γ-unsaturated nitriles in high yields.
- Tsuji, Yasushi,Yamada, Naoaki,Tanaka, Shinsuke
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- REACTION OF DIALKYLDITHIOTRIMETHYLSILYLPHOSPHITES WITH ACYL HALIDES
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It has been established that S,S-dialkyltrimethylsilyldithiophosphites react with acyl halides in two directions, depending on the nature of the halogen in the acyl halide and on the reaction conditions, thus giving as the main reactions products either dialkyldithiohalophosphites or dialkyldithioacylphosphonates.The latter compounds react with acyl halides in accordance with retro-Arbuzov reaction scheme, giving dialkyldithiohalophosphites. Keywords: dialkyldithiotrimethylsilylphosphites, acyl halides, dialkyldithioacylphosphites, dialkyldithioacylphosphonates.
- Al'fonsov, V. A.,Trusenev, A. G.,Gainullin, R. M.,Batyeva, E. S.,Pudovik, A. N.
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p. 799 - 803
(2007/10/02)
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- Esters of (Hydroxymethyl)diorganylsilanes: Synthesis and Thermally Induced Rearrangement
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Twenty silanes of the type R1R2Si(H)CH3OR3 (A) were synthesized 1,R2 = Me, Ph, 1-naphthyl, PhCH2, Me3SiCH2; OR3 = OC(O)Me, OC(O)CF3, OS(O)CF3, OP(O)Ph2, OC(O)Cl> and studied for their thermal behaviour.The silanes A undergo a thermally induced rearrangement to give the corresponding silanes R1R2Si(OR3)Me (B).For compounds with OR3 = OC(O)Cl, an additional decarboxylation takes place to yield the chlorosilanes R1R2Si(Cl)Me.Except for the derivatives with OR3 = OC(O)Cl, the energetic (reaction enthalpy) and kinetic data (reaction order, frequency factor, enthalpy and entropy of activation) of these reactions were studied by means of differential scanning calorimetry (DSC).In addition the kinetics of all reactions were investigated by 1H-NMR spectroscopy.The transition state of the rearrangement was investigated by an ab initio study based on the model compound H3SiCH2OC(O)H MeH2SiOC(O)H>.The theoretical data and the experimentally obtained energetic and kinetic data are discussed in terms of mechanistic aspects of the rearrangement reaction A -> B.
- Tacke, Reinhold,Wiesenberger, Frank,Becker, Beate,Rohr-Aehle, Regine,Schneider, Petra B.,et al.
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p. 591 - 606
(2007/10/02)
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- REACTIONS OF 2-AMINO-4,5-BENZO-1,3,2-DIOXAPHOSPHOLANE WITH CARBOXYLIC AND PHOSPHOROUS ACIDS AND ACETIC ANHYDRIDE
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The reactions of 2-amino-4,5-benzo-1,3,2-dioxaphospholane with acetic acid, benzoic acid, and acetic anhydride yield 2-trimethylsiloxy-4,5-benzo-1,3,2-dioxaphospholane.Upon reaction with dialkyl phosphites, the silylamidophosphite acts as a silylating agent.
- Pudovik, M. A.,Kibardina, L. K.,Pudovik, A. N.
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p. 214 - 216
(2007/10/02)
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- Palladium-Catalyzed Coupling Reactions of Aryl Triflates or Halides with Ketene Trimethylsilyl Acetals. A New Route to Alkyl 2-Arylalkanoates
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Palladium complexes with phosphines, in the presence of lithium acetate, catalyze the coupling reaction of aryl triflates and ketene trimethylsilyl acetals to yield alkyl 2-arylalkanoates, 1,1'-bis(diphenylphosphino)ferrocene gives the best results.Aryl halides may also be used, provided that a stoichiometric amount of thallium acetate is present.Added acetate anions act both as palladium-bonded groups in the ArPdL2OAc reactive intermediate and as nucleophiles promoting the Si-O bond breaking of the silyl enolate moiety.The reaction represents a novel method for the preparation of alkyl 2-arylalkanoates which, after hydrolysis, afford the corresponding 2-alkylalkanoic acids, well known as antiinflammatory and antipyretic drugs.
- Carfagna, Carla,Musco, Alfredo,Sallese, Gianna,Santi, Roberto,Fiorani, Tiziana
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p. 261 - 264
(2007/10/02)
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- Diiodosilane. 3. Direct Synthesis of Acyl Iodides from Carboxylic Acids, Esters, Lactones, Acyl Chlorides, and Anhydrides
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Diiodosilane (SiH2I2, DIS) is a very useful reagent for direct, high yield synthesis of acyl iodides from variety of carboxylic acid derivatives, such as carboxylic acids, esters, lactones, anhydrides, and acyl chlorides.These transformations are remarkably accelerated by iodine.In the absence of iodine DIS reacts with carboxylic acids and esters, much as does iodotrimethylsilane (TMSI), to form the corresponding silyl carboxylates.However, in contrast to TMSI, DIS and iodine react further with silyl carboxylates to produce acyl iodides.This reaction, when followed by addition of an appropriate alcohol, represents an esterification and transesterification method that is useful even for sterically hindered and/or poorly nucleophilic alcohols.Lactones react with DIS to produce either silyl ω-iodo carboxylates or ω-iodoacyl iodides, depending on the reaction conditions.The reaction between DIS and 1 equiv of a carboxylic anhydride affords, in the presence of iodine, 2 equiv of acyl iodide.
- Keinan, E.,Sahai, M.
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p. 3922 - 3926
(2007/10/02)
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- CHROMIUM(II) CHEMISTRY IN N,N-DIMETHYLFORMAMIDE. PART III. CHROMIUM(II) INTERACTION WITH ORGANOCHLOROSILANES
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It has been found that organochlorosilanes react in dimethylformamide (DMF) with chromium(II) compounds.The action of chromium(II) on the Si-Cl bond, contrary to that on a C-Cl bond, exhibits a character of a substitution reaction leading to the formation of CrCl2*2DMF as well as an organosilicon derivative containing the anion of the initial Cr(II) salt.Crystalline precipitates of Cr(II) compounds containing some chlorosilane have been obtained, which suggests that Cr(II)-chlorosilane complexes are formed as intermediates.
- Duczmal, Wojciech
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- Reactivity of the Labile Silaethene Me2Si=C(SiMe3)2, Stored as Ph2C=NSiMe3 Adducts
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Silaethene Me2Si=C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 deg C as a reaction intermediate, combines with reactants a-b (e.g.HO-H, RO-H, RCOO-H, RS-H, RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g.O=CPh2, Me3SiN=CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g.RN=N=N, O=N=N), a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under -, - as well as -c ycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene, 2,3-dimethylbutadiene, acetone) under ene reaction.According to relative reaction rates, insertion and -cycloadditions seem to proceed in two reaction steps, whereas -cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions.For reactivities cf.Table I. - Key words: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Relative Reactivities
- Wiberg, N.,Preiner, G.,Wagner, G.,Koepf, H.
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p. 1062 - 1074
(2007/10/02)
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- REACTIONS IN THE CHLOROSILANE-SILANOL-SILOXANE SYSTEM
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We obtained the first ?*-values and ES-values for siloxy groups by spectroscopic and kinetic methods.Detailed mechanistic investigations are performed on the hydrolysis of chlorosilanes, the cleavage of Si-O-Si bonds by HCl, and the substituent exchange reaction between silanols and chlorosilanes.
- Ruehlmann, K.
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p. 139 - 152
(2007/10/02)
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- Method for the simultaneous preparation of carboxylic acid trimethylsilyl esters and silylated carboxylic acid amides
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Carboxylic acid trimethylsilyl esters (I) and trimethylsilyl carboxylic acid amides can be prepared simultaneously from the corresponding carboxylic acid anhydrides; the esters (I) and monocarboxylic acid trimethylsilyl amides are formed first and can then be recovered, or else the bis-trimethylsilyl carboxylic acid amides are formed by further transposition with trimethylchlorosilane in the presence of tertiary amines, and are separated from the carboxylic acid trimethylsilyl ester (I) and recovered.
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- ZUR SYNTHESE VON SILOXANEN. II, STERISCHE SUBSTITUENTENKONSTANTEN FUER SILOXYRESTE
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The acetolysis reactions of compounds of the type XSiMe2Cl (I) with acetic acid in the presence of acetic anhydride were studied kinetically by means of 1H NMR spectroscopy.We found these reactions exclusively influenced by steric effects (ρ=0).The steric susceptibility constant (δ) of the acetolysis reaction, using alkylchlorodimethylsilanes was found to be 1.3.In this investigation the Taft Es nvalues showed a better correlation than the Es(Si) values of Cartledge.From the rate constants of the acetolysis reactions with I (X=Cl, acetoxy or siloxy) we could then obtain for the first time Es values for Cl, acetoxy and a series of siloxy groups at silicon.
- Scheim, U.,Grosse-Ruyken, H.,Ruehlmann, K.,Porzel, A.
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- Catalytic Conversion of Allylic Esters to Corresponding Allylic Silanes with Hexamethyldisilane and Palladium(0) or Rhodium(I) Complexes
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Treatment of allylic esters (R1CH=CR2CH2OCOR3:R1=H,Ar;R2=H, alkyl; and R3=Me,Ph) with hexamethyldisilane in the presence of catalytic amounts of PdL4 (L=PPh3 or P(OPh)3) or RhCl(PPh3)3 gives the corresponding allylic silanes in the excellent yield.
- Urata, Hisao,Suzuki, Hiroharu,Moro-oka, Yoshihiko,Ikawa, Tsuneo
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p. 607 - 608
(2007/10/02)
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- EQUILIBRIA BETWEEN MexSiCl4-x, x = 3,2,1,0 AND ALKYL CARBOXYLATE ESTERS
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At 150 deg C equilibria are established between chlorosilanes and alkyl esters according to the equation: MexSiCl4-x + RCOOR' MexSi(O0.5)y(OOCR)z-yCl4-x-y-z + yRCOCl + zR'Cl.When x = 3, y = 0, z = 0.56; when x = 2, y = 0.26, z = 0.98.When x = 1, y = z = 0.56; when x = 0, y = z = 0.53.Lewis acid salts such as ZnCl2 or FeCl3 are effective catalysts for the reactions leading to mixtures of these compounds.
- Mbah, Godfrey C.,Speier, John L.
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- TRIMETHYLSILYLATED N-ALKYL-SUBSTITUTED CARBAMATES. I. PREPARATION AND SOME REACTIONS
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Trimethylsilyl N-monoalkyl- and N,N-dialkyl-carbamates have been made in 85-95percent yields by silylation of the corresponding ammonium carbamates with trimethylchlorosilane.Trimethylsilyl N,N-dimethylcarbamate can be used for silylation of alcohols, phenols, and carboxylic acids.The silylcarbamates react with carboxylic acid halides to give the corresponding acid amides.The reaction of trimethylsilyl carbamates with carboxylic anhydrides give the corresponding silyl carboxylate and acid amide, while the reaction with dicarboxylic anhydrides give the trimethylsilyl monoamide of the corresponding dicarboxylic acid, i.e.Me3SiO2CCONR1R2.
- Knausz, Dezsoe,Meszticzky, Aranka,Szakacs, Laszlo,Csakvari, Bela,Ujszaszy, Kalman
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- Interhalogen-Catalyzed Cleavages of Ethers and Esters with Trimethylsilyl Bromide or Chloride
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The cleavages of various dialkyl ethers, trimethylsilyl alkyl ethers, and alkyl esters by trimethylsilyl bromide are strongly catalyzed by iodine monobromide.This catalyzed cleavage procedure using iodine monobromide makes possible synthetic applications for trimethylsilyl bromide which were previously ruled out by problems with its low reactivity.Cleavages of benzylic and tertiary alkyl ethers and esters by trimethylsilyl chloride are feasible when catalyzed by iodine monochloride.However, other systems are essentially unreactive toward trimethylsilyl chloride even in the presence of iodine monochloride.
- Friedrich, Edwin C.,DeLucca, George
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p. 1678 - 1682
(2007/10/02)
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- Thermally Induced Rearrangement of (Acyloxymethyl)diorganylsilanes
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The (acyloxymethyl)diorganylsilanes R1R2Si(H)CH2OC(O)R3 (2a-d) rearrange to the corresponding acyloxy(methyl)diorganylsilanes R1R2Si(CH3)OC(O)R3 (3a-d).This reaction is formally equivalent to an exchange of the hydrogen bound to silicon and acyloxy group bound to carbon.The 1,2-hydrogen shift could be shown experimentally to be an intramolecular process.
- Tacke, Reinhold,Lange, Hartwig
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p. 3685 - 3691
(2007/10/02)
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- The Mechanism of the Gas-Phase Pyrolysis of Esters. Part 13. The Very Strong Activating Effects of β-Trialkylmetal Groups
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The rates of gas-phase pyrolysis of β-substituted ethyl acetates AcOCH2CH2X where X=SiMe3, SiEt3, GeEt3, and SiMe2Ph, and of 1-aryl-2-trimethylsilylethyl acetates have each been measured over a minimum of 50 deg C, between 282 and 397 deg C; the rates of pyrolysis of 2-aryldimethylsilylethyl acetates have been measured at 396.9 and 378.2 deg C.The β-organometallic substituents are not themselves eliminated (except at considerably higher temperatures) but strongly accelerate the normal elimination of acetic acid, the relative rates per β-hydrogen at 327 deg C for X being: H, 1.0; SiMe3, 125; SiEt3, 179; GeEt3, 108; SiMe2Ph, 144.These groups appear to activate by a combination of increasing the acidity of the β-hydrogen via stabilisation of the forming β-carbanion through (p->d)? bonding, stabilisation of the incipient α-carbocation by C-X hyperconjugation, and steric acceleration.The effect of substituents in the aryl ring of 1-aryl-2-trimethylsilylethyl acetates gave an excellent correlation with ?+ values with ρ - 0.52 at 327 deg C.The lower ρ-factor for this reaction compared to that for 1-arylethyl acetates (-0.66) is consistent with either conjugative stabilisation of the α-carbocation or increased β-hydrogen acidity.Substituents in the aryl ring of 2-aryldimethylsilylethyl acetates gave a very small positive ρ-factor indicating that overall their effect on β-hydrogen acidity is larger than that on the forming carbocation.The product of pyrolysis of AcO.CH2.CH2.GeEt3 viz.CH2=CHGeEt3 underwent increasingly rapid elimination of successive moieties, believed to be ethylene, in a reaction of stoicheiometry 4.0, which did not occur with the silicon analogue.
- Eaborn, Colin,Mahmoud, Foad M. S.,Taylor, Roger
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p. 1313 - 1320
(2007/10/02)
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