- ALCOHOLYSIS OF HYDRIDESILANES TO GIVE SILYL ETHERS CATALYZED BY RHODACARBORANES CLOSO-3,3-(Ph3P)2-3-H-3,1,2-RhC2B9H11 AND CLOSO-3,3-(η2,η3-C7H7CH2)-3,1,2-RhC2B9H11
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Rhodacarboranes closo-3,3-(Ph3P)2-3-H-3,1,2-RhC2B9H11 and closo-(η2,η3-C7H7CH2)-3,1,2-RhC2B9H11 are catalysts for the alcoholysis of hydridesilanes.Closo-(η2,η3-C7H7CH2)-3,1,2-RhC2B9H11 displays greater activity
- Zakharkin, L. I.,Zhigareva, G. G.
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- Charge Modified Porous Organic Polymer Stabilized Ultrasmall Platinum Nanoparticles for the Catalytic Dehydrogenative Coupling of Silanes with Alcohols
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Developing an ideal stabilizer to prevent the aggregation of nanoparticles is still a big challenge for the practical application of noble metal nanocatalysts. Herein, we develop a charge (NTf2?) modified porous organic polymer (POP-NTf2) to stabilize ultrasmall platinum nanoparticles. The catalyst is characterized and applied in the catalytic dehydrogenative coupling of silanes with alcohols. The catalyst exhibits excellent catalytic performance with highly dispersed ultrasmall platinum nanoparticles (ca. 2.22?nm). Moreover, the catalyst can be reused at least five times without any performance significant loss and Pt NPs aggregation. Graphic Abstract: [Figure not available: see fulltext.]
- Chen, Chao,Cheng, Dan,Ding, Shunmin,Liang, Sanqi,Liu, Senqun,Ma, Xiaohua,Su, Tongtong,Wu, Shaohua,Zeng, Rong
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- Cobalt single atoms anchored on nitrogen-doped porous carbon as an efficient catalyst for oxidation of silanes
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The oxidation reactions of organic compounds are important transformations for the fine and bulk chemical industry. However, they usually involve the use of noble metal catalysts and suffer from toxic or environmental issues. Here, an efficient, environmentally friendly, and atomically dispersed Co catalyst (Co-N-C) was preparedviaa simple, porous MgO template and etching method using 1,10-phenanthroline as C and N sources, and CoCl2·6H2O as the metal source. The obtained Co-N-C catalyst exhibits excellent catalytic performance for the oxidation of silanes with 97% isolated yield of organosilanol under mild conditions (room temperature, H2O as an oxidant, 1.8 h), and good stability with 95% isolated yield after nine consecutive reactions. The turnover frequency (TOF) is as high as 381 h?1, exceeding those of most non-noble metal catalysts and some noble metal catalysts. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), extended X-ray absorption fine structure (EXAFS), and wavelet transform (WT) spectroscopy corroborate the existence of atomically dispersed Co. The coordination numbers of Co affected by the pyrolysis temperature in Co-N-C-700, Co-N-C-800, and Co-N-C-900 are 4.1, 3.6, and 2.2, respectively. Owing to a higher Co-N3content, Co-N-C-800 shows more outstanding catalytic performance than Co-N-C-700 and Co-N-C-800. Moreover, density functional theory (DFT) calculations reveal that the Co-N3structure exhibits more activity compared with Co-N4and Co-N2, which is because the Co atom in Co-N3was bound with both H atom and Si atom, and it induced the longest Si-H bond.
- Yang, Fan,Liu, Zhihui,Liu, Xiaodong,Feng, Andong,Zhang, Bing,Yang, Wang,Li, Yongfeng
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p. 1026 - 1035
(2021/02/09)
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- Swollen-induced in-situ encapsulation of chiral silver catalysts in cross-linked polysiloxane elastomers: Homogeneous reaction and heterogeneous separation
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The immobilization of molecular catalysts to fabricate heterogeneous catalysts for catalytic asymmetric transformations is extremely important and has attracted great attentions. Herein we developed a simple and new strategy for the heterogenization of ho
- Li, Li,Wu, Shi-Lu,Xu, Li-Wen,Xu, Zheng,Yan, Jun-Hao,Yang, Ke-Fang,Yang, Meng-Meng,Yin, Guan-Wu,Zhang, Peng-Fei
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- Mechanistic Studies on the Hexadecafluorophthalocyanine–Iron-Catalyzed Wacker-Type Oxidation of Olefins to Ketones**
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The hexadecafluorophthalocyanine–iron complex FePcF16 was recently shown to convert olefins into ketones in the presence of stoichiometric amounts of triethylsilane in ethanol at room temperature under an oxygen atmosphere. Herein, we describe an extensive mechanistic investigation for the conversion of 2-vinylnaphthalene into 2-acetylnaphthalene as model reaction. A variety of studies including deuterium- and 18O2-labeling experiments, ESI-MS, and 57Fe M?ssbauer spectroscopy were performed to identify the intermediates involved in the catalytic cycle of the oxidation process. Finally, a detailed and well-supported reaction mechanism for the FePcF16-catalyzed Wacker-type oxidation is proposed.
- Grinenko, Vadim,Klau?, Hans-Henning,Kn?lker, Hans-Joachim,Puls, Florian,Seewald, Felix
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p. 16776 - 16787
(2021/11/04)
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- Half-sandwich ruthenium(ii) complexes with tethered arene-phosphinite ligands: Synthesis, structure and application in catalytic cross dehydrogenative coupling reactions of silanes and alcohols
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The preparation of the tethered arene-ruthenium(ii) complexes [RuCl2{η6:κ1(P)-C6H5(CH2)nOPR2}] (R = Ph, n = 1 (9a), 2 (9b), 3 (9c); R = iPr, n = 1 (10a), 2 (10b), 3 (10c)) from the corresponding phosphinite ligands R2PO(CH2)nPh (R = Ph, n = 1 (1a), 2 (1b), 3 (1c); R = iPr, n = 1 (2a), 2 (2b), 3 (2c)) is presented. Thus, in a first step, the treatment at room temperature of tetrahydrofuran solutions of dimers [{RuCl(μ-Cl)(η6-arene)}2] (arene = p-cymene (3), benzene (4)) with 1-2a-c led to the clean formation of the corresponding mononuclear derivatives [RuCl2(η6-p-cymene){R2PO(CH2)nPh}] (5-6a-c) and [RuCl2(η6-benzene){R2PO(CH2)nPh}] (7-8a-c), which were isolated in 66-99% yield. The subsequent heating of 1,2-dichloroethane solutions of these compounds at 120 °C allowed the exchange of the coordinated arene. The substitution process proceeded faster with the benzene derivatives 7-8a-c, from which complexes 9-10a-c were generated in 61-82% yield after 0.5-10 h of heating. The molecular structures of [RuCl2(η6-p-cymene){iPr2PO(CH2)3Ph}] (6c) and [RuCl2{η6:κ1(P)-C6H5(CH2)nOPiPr2}] (n = 1 (10a), 2 (10b), 3 (10c)) were unequivocally confirmed by X-ray diffraction methods. In addition, complexes [RuCl2{η6:κ1(P)-C6H5(CH2)nOPR2}] (9-10a-c) proved to be active catalysts for the dehydrogenative coupling of hydrosilanes and alcohols under mild conditions (r.t.). The best results were obtained with [RuCl2{η6:κ1(P)-C6H5(CH2)3OPiPr2}] (10c), which reached TOF and TON values up to 117 600 h-1 and 57 000, respectively.
- González-Fernández, Rebeca,Crochet, Pascale,Cadierno, Victorio
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p. 210 - 222
(2019/12/28)
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- Coexistence of Cu(ii) and Cu(i) in Cu ion-doped zeolitic imidazolate frameworks (ZIF-8) for the dehydrogenative coupling of silanes with alcohols
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Recently, metal-ion-doped zeolitic imidazolate frameworks have gained considerable attention for their structure tailorability and potential catalytic applications. Herein, Cu ion-doped ZIF-8 nanocrystals were successfully prepared by the mechanical grind
- Dai, Yan,Xing, Peng,Cui, Xiaoqin,Li, Zhihong,Zhang, Xianming
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p. 16562 - 16568
(2019/11/19)
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- High Production of Hydrogen on Demand from Silanes Catalyzed by Iridium Complexes as a Versatile Hydrogen Storage System
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The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. The catalyst, an iridium complex of the formula [IrCp?(Cl)2(NHC)] containing an N-heterocyclic carbene (NHC) ligand functionalized with a pyrene tag, catalyzes efficiently the reaction at room temperature producing H2 quantitatively within a few minutes. As a result, the dehydrogenative coupling of 1,4-disilabutane and methanol enables an effective hydrogen storage capacity of 4.3 wt % that is as high as the hydrogen contained in the dehydrogenation of formic acid, positioning the silane/alcohol pair as a potential liquid organic hydrogen carrier for energy storage. In addition, the heterogenization of the iridium complex on graphene presents a recyclable catalyst that retains its activity for at least 10 additional runs. The homogeneous distribution of catalytic active sites on the basal plane of graphene prevents diffusion problems, and the reaction kinetics are maintained after immobilization.
- Ventura-Espinosa, David,Sabater, Sara,Carretero-Cerdán, Alba,Baya, Miguel,Mata, Jose A.
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p. 2558 - 2566
(2018/03/13)
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- Platinum Complexes with a Phosphino-Oxime/Oximate Ligand
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The platinum(II) complex [PtCl2(COD)] (2; COD = 1,5-cyclooctadiene) reacted with 1 and 2 equiv. of 2-(diphenylphosphanyl)benzaldehyde oxime (1) to generate [PtCl2{κ2-(P,N)-2-Ph2PC6H4CH=NOH}] (3) and [Pt{κ2-(P,N)-2-Ph2PC6H4CH=NOH}2][Cl]2 (4), respectively. Deprotonation of the oxime hydroxyl group of 3 with Na2CO3 led to the selective formation of the dinuclear species (μ-O)-[PtCl{κ2-(P,N)-2-Ph2PC6H4CH=NO}]2 (5), while the related methylated derivative (μ-O)-[PtMe{κ2-(P,N)-2-Ph2PC6H4CH=NO}]2 (7) could be obtained from the direct reaction of [PtMe2(COD)] (6) with the phosphino-oxime ligand 1. In the case of 4, its treatment with Na2CO3 yielded complex [Pt({κ2-(P,N)-2-Ph2PC6H4CH=NO}2H)][Cl] (8), as a result of the deprotonation of only one of the OH groups of 4. On the other hand, contrary to what was observed with 6, no deprotonation of the oxime occurred in the reaction of [PtMe3I]4 (9) with 1, from which the mononuclear PtIV derivative fac-[PtIMe3{κ2-(P,N)-2-Ph2PC6H4CH=NOH}] (10) was isolated. The solid-state structures of compounds 3, 4, 7 and 10 were determined by X-ray crystallography. In addition, the potential of all the synthesized complexes as catalysts for the dehydrogenative coupling of hydrosilanes with alcohols is also briefly discussed.
- Francos, Javier,Borge, Javier,Conejero, Salvador,Cadierno, Victorio
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p. 3176 - 3186
(2018/07/31)
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- METHOD FOR PREPARING ARYLALKOXYSILANES BY DEHYDROGENATIVE SILYLATION
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Claimed is a method involving dehydrogenative silylation of aromatic compounds under Rh-catalysis to give an arylalkoxysilane. The method includes the steps of: 1) combining, under conditions appropriate to form the arylalkoxysilane, starting materials including A) an alkoxysilane having at least one silicon bonded hydrogen atom per molecule; (I) B) an aromatic compound having a carbon-hydrogen bond; and C) a rhodium bisphospholane catalyst. Additional starting materials such as D) a hydrogen acceptor and/or E) a solvent may be added during step 1). The method may further include 2) recovering the arylalkoxysilane. In a preferred embodiment the Rhodium bisphospholane catalyst is of type (II).
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Paragraph 0024; 0025; 0026
(2018/11/10)
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- Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier
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The compound [Ru(p-cym)(Cl)2(NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC.
- Ventura-Espinosa, David,Carretero-Cerdán, Alba,Baya, Miguel,García, Hermenegildo,Mata, Jose A.
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supporting information
p. 10815 - 10821
(2017/08/18)
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- Synthesis of nitrogen and sulfur co-doped hierarchical porous carbons and metal-free oxidative coupling of silanes with alcohols
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Hierarchically porous N and S co-doped carbon was prepared by using 2,5-dihydroxy-1,4-benzoquinone as the carbon source, thiourea as the N and S source, and SiO2 particles as the template. Using the material as the catalyst, oxidative coupling of silanes with alcohols was conducted for the first time under metal-free conditions.
- Chen, Bingfeng,Li, Fengbo,Mei, Qingqing,Yang, Youdi,Liu, Huizhen,Yuan, Guoqing,Han, Buxing
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supporting information
p. 13019 - 13022
(2017/12/15)
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- Silica-supported ultra small gold nanoparticles as nanoreactors for the etherification of silanes
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Ultra small gold nanoparticles supported by porous silica (Au-SiO2) were successfully synthesized. Due to enrichment of reactants by silica, the Au-SiO2 particles functioned as nanoreactors for catalytic etherification of silanes wit
- Wang, Cui,Lin, Xijie,Ge, Yuzhen,Shah, Zameer Hussain,Lu, Rongwen,Zhang, Shufen
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p. 102102 - 102108
(2016/11/09)
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- Dehydrogenative coupling of silanes with alcohols catalyzed by Cu3(BTC)2
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Cu3(BTC)2 is an efficient and reusable heterogeneous catalyst for the dehydrogenative coupling of silanes with alcohols. Activity data and CO adsorption suggest that Cu(ii) and in situ generated Cu(i) are the active species. Other MOFs such as Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are unable to promote this cross-coupling.
- Dhakshinamoorthy, Amarajothi,Concepcion, Patricia,Garcia, Hermenegildo
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supporting information
p. 2725 - 2728
(2016/02/19)
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- Copper-Catalyzed Asymmetric Three-Component Borylstannation: Enantioselective Formation of C-Sn Bond
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In summary, a first copper-catalyzed synthesis of α-aryl-β-borylstannane compounds was accomplished through three-component borylstannation of aryl-substituted alkenes. In the exploration of an asymmetric variant, chiral sulfinylphosphine ligands proved a
- Jia, Tao,Cao, Peng,Wang, Ding,Lou, Yazhou,Liao, Jian
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supporting information
p. 4918 - 4922
(2015/03/30)
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- Reduction of quinolines to 1,2,3,4-tetrahydroquinolines with hydrosilane/ethanol catalyzed by TiO2-supported gold nanoparticles under solvent free conditions
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Gold nanoparticles supported on TiO2 (1 mol%) catalyze the reduction of a series of functionalized quinolines into 1,2,3,4-tetrahydroquinolines using hydrosilanes/ethanol (hydride/proton) as the reductant system. A typical reaction requires 4 molar equivalents of phenyldimethylsilane (reductant of choice), 4 molar equivalents of ethanol as a reagent and heating to 70 °C under solvent free conditions. The isolated yields are moderate to excellent and in certain cases the reaction rate is exceedingly fast. Mechanistic analysis revealed the stereoselective addition of two hydrides (from hydrosilane) on positions C2 and C4 of the quinoline ring and two protons (from ethanol) on positions C3 and the nitrogen atom.
- Louka, Anastasia,Gryparis, Charis,Stratakis, Manolis
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- Nanoporous palladium catalyzed silicon-based one-pot cross-coupling reaction of aryl iodides with organosilanes
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One-pot cross-coupling of aryl iodides with organosilanes is realized in excellent yield by utilizing dealloyed nanoporous palladium as a sustainable and heterogeneous catalyst. The reaction is completed under mild conditions and the catalyst can be reused several times without evident loss of its catalytic activity. This journal is the Partner Organisations 2014.
- Li, Zhiwen,Lin, Sha,Ji, Lisha,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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p. 1734 - 1737
(2014/06/09)
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- Highly selective oxidation of organosilanes with a reusable nanoporous silver catalyst
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Room temperature highly selective oxidation of organosilanes to organosilanols and organosilyl ethers is achieved in liquid-phase with dealloyed nanoporous silver catalysts. In both cases, aromatic and aliphatic silanes can be effectively converted into the corresponding silanols and silyl ethers by using water and alcohols as oxidant, respectively. Moreover, hydrogen gas is the only by-product and the catalyst can be recycled for several times without evident loss of activity and selectivity.
- Li, Zhiwen,Zhang, Congcong,Tian, Jing,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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- Copper nanoparticles supported on doped graphenes as catalyst for the dehydrogenative coupling of silanes and alcohols
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Copper nanoparticles (NPs) supported on a series of undoped and doped graphene materials (Gs) have been obtained by pyrolysis of alginate or chitosan biopolymers, modified or not with boric acid, containing Cu2+ ions at 900 °C under inert atmosphere. The resulting Cu-G materials containing about 17 wt% Cu NPs (from 10 to 200 nm) exhibit high catalytic activity for the dehydrogenative coupling of silanes with alcohols. The optimal material consisting on Cu-(B)G is more efficient than Cu NPs on other carbon supports.
- Blez, Juan F.,Primo, Ana,Asiri, Abdullah M.,lvaro, Mercedes,Garc, Hermenegildo
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supporting information
p. 12581 - 12586
(2015/04/16)
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- Chemo- and regioselective catalytic reduction of N-heterocycles by silane
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The ruthenium complex [Cp(iPr3P)Ru(NCCH3) 2]+ (1) catalyzes the regioselective hydrosilylation of pyridines to 1,4-dihydropyridines. Substitution in the 3- and 5-positions is tolerated, whereas pyridines with substituents in the 2-, 4-, and 6-positions are not reduced. Reduction of functionalized pyridines having keto and ester substituents results in a mixture of products. N-Silyl-1,4-dihydropyridine reacts with ketones and aldehydes to give products of N-Si addition across the C=O bond. Hydrosilylation of pyridine in acetone results quantitatively in the addition product PhMe2SiO-CMe2-NC5H 6, which decomposes in hexane to give the parent dihydropyridine HNC5H6. The phenanthroline complex [Cp(phen)Ru(NCCH 3)2]+ (10) catalyzes regioselective 1,4-reduction of phenanthroline by a 3-4-fold excess of silane/water or silane/alcohol mixtures. The Cp* analogue [Cp*(ph n)Ru(NCCH 3)2]+ (9) catalyzes 1,4-regioselective monohydrosilylation of phenanthroline, quinoline, acridine, and 1,3,5-triazine and the 1,2-reduction of isoquinoline. In contrast, 2-substituted phenanthroline, pyrazine, 2-ethylpyridine, 2,6-lutidine, 2,4-lutidine, and pyrimidine are not reduced under these conditions by either of the catalysts studied.
- Lee, Sun-Hwa,Gutsulyak, Dmitry V.,Nikonov, Georgii I.
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p. 4457 - 4464
(2013/09/23)
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- N-heterocyclic carbene organocatalysts for dehydrogenative coupling of silanes and hydroxyl compounds
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Go organic! N-Heterocyclic carbene (NHC) 1,3-diisopropyl-4,5- dimethylimidazol-2-ylidene (IiPr) has been found to be an efficient and selective catalyst for the dehydrogenative coupling of a wide range of silanes and hydroxyl groups to form Si-O bonds under mild and solvent-free conditions (see scheme). Mechanistic studies indicated that the activation of hydroxyl groups by the NHC is the most plausible initial step for the process. Copyright
- Gao, Dongjing,Cui, Chunming
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supporting information
p. 11143 - 11147
(2013/09/02)
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- Highly efficient etherification of silanes by using a gold nanoparticle catalyst: Remarkable effect of O2
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O2 is acting! A nanosized hydroxylapatite-supported Au nanoparticle (NP) catalyst exhibited high activity under aerobic conditions, and various silyl ethers could be obtained from diverse combinations of silanes with alcohols. Moreover, O2 was found to act not as a stoichiometric oxidizing reagent, but as a non-consumed promoter, significantly boosting the catalytic activity of AuNPs (see figure). Copyright
- Mitsudome, Takato,Yamamoto, Yuya,Noujima, Akifumi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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p. 14398 - 14402
(2013/11/06)
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- Enhanced catalytic activity of self-assembled-monolayer-capped gold nanoparticles
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An unprecedented substrate-selective catalytic enhancement effect of an alkanethiol-self-assembled monolayer (SAM) on Au nanoparticles (AuNPs) is reported. In the supported 2D-array of AuNPs, the alkanethiol-SAM acts as a protein-like soft reaction space
- Taguchi, Tomoya,Isozaki, Katsuhiro,Miki, Kazushi
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p. 6462 - 6467
(2013/02/23)
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- PROCESS FOR PRODUCTION OF HYDROXYTYROSOL USING ORGANOMETALLIC COMPOUNDS
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Disclosed is a process for the production of a 4-(2-hydroxyalkyl)-1,2-benzenediol, comprising the steps of (a) providing protected 1,2-benzenediol having the 1,2-hydroxyl groups protected, (b) halogenating the protected 1,2-benzenediol to obtain a protected 4-halo-1,2-benzenediol having the 1,2-hydroxyl groups protected, (c) reacting, in the presence of a metal or organometallic compound, the protected 4-halo-1,2-benzenediol to protected 4-(2-hydroxyalkyl)-1,2-benzenediol having the 1,2-hydroxyl groups protected, and (d) deprotecting the protected 4-(2-hydroxyalkyl)-1,2-benzenediol to obtain the 4-(2-hydroxyalkyl)-1,2-benzenediol. Also disclosed is the use of 1,2-benzenediol for the production of hydroxytyrosol.
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Page/Page column 16-17
(2012/02/02)
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- An efficient method for the synthesis of symmetrical disiloxanes from alkoxysilanes using Meerwein's reagent
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We report here a new and efficient route to symmetrical disiloxanes from their corresponding alkoxysilanes using Meerwein's reagent as mediator and potassium carbonate as additive under mild reaction conditions in acetonitrile. Our methodology is very simple, economic, and high yielding. We have also proposed a reaction mechanism with the plausible silyloxonium intermediates. Georg Thieme Verlag Stuttgart · New York.
- Jorapur, Yogesh R.,Shimada, Toyoshi
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supporting information; experimental part
p. 1633 - 1638
(2012/08/07)
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- Cu(II)-impregnated sulfated MCM-41: An efficient and convenient protocol for the synthesis of 1,3-benzodioxoles
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An efficient synthesis of 1,3-benzodioxoles was achieved from catechol with different aldehydes and ketones using Cu(II) impregnated sulfated MCM-41 as an efficient and reusable catalyst. Copyright Taylor & Francis Group, LLC.
- Sivakumar,Ramesh,Lalitha
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experimental part
p. 91 - 93
(2011/03/23)
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- Microwave-assisted synthesis of 1,3-benzodioxole derivatives from catechol and ketones or aldehydes
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An efficient synthetic procedure for the preparation of a diverse library of 1,3-benzodioxoles was developed by applying controlled microwave heating in comparison with currently available conventional heating. Reactions were completed in less than 3 h. The isolation of product is simple, the isolated yields are good to excellent, and this method is applicable to large scale production.
- Pingali, Subramanya R.K.,Jursic, Branko S.
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experimental part
p. 4371 - 4374
(2011/09/19)
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- Cationic silane δ-complexes of ruthenium with relevance to catalysis
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Hydrosilylation of carbonyls catalyzed by 2 goes via intermediate formation of cationic silane σ-complexes 4 which undergo nucleophilic abstraction of the silylium cation studied by DFT calculations.
- Gutsulyak, Dmitry V.,Vyboishchikov, Sergei F.,Nikonov, Georgii I.
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supporting information; experimental part
p. 5950 - 5951
(2010/07/05)
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- The β-silicon effect. 4: Substituent effects on the solvolysis of 1-alkyl-2-(aryldimethylsilyl)ethyl trifluoroacetates
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Solvolysis rates of 2-(aryldimethylsilyl)-1-methylethyl and 2-(aryldimethylsilyl)-1-tert-butylethyl trifluoroacetates were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silicon atom on the solvolysis rates at 50 °C were correlated with σmacr; parameters of r+ = 0.15 with the Yukawa-Tsuno equation, giving ρ values of-1.5 for both secondary α-Me and α-tert-Bu systems. The ρ values for those secondary systems are less negative than-1.75 for the 2-(aryldimethylsilyl)ethyl system that proceeds by the Eaborn (non-vertical) mechanism, while they are distinctly more negative than-0.99 for 2-(aryldimethylsilyl)-1-phenylethyl system that should proceed by the Lambert (vertical) mechanism. There was a fairly linear relationship between the reaction constants (ρ) for the β-silyl substituent effects and the solvolysis reactivities for a series of β-silyl substrates. The solvolyses of the α-Me and tert-Bu substrates proceed through the transition state (TS) with an appreciable degree of the β-silyl participation, close to the Eaborn (non-vertical) TS rather than to the Lambert (vertical) TS. Copyright
- Fujiyama, Ryoji,Alam, Md. Ashadul,Shiiyama, Aiko,Munechika, Toshihiro,Fujio, Mizue,Tsuno, Yuho
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p. 819 - 827
(2011/04/24)
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- Diallylation of 2,2-dialkylbenzodioxoles from TiCl4-mediated allylsilane reaction
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Reaction of aliphatic ketones with catechol afforded 2,2-dialkylbenzodioxoles. Treatment of these benzodioxoles with allyltrimethylsilane in the presence of titanium tetrachloride led to 4,4-dialkylhepta-1,6-dienes resulting from a diallylation process. R
- Galy, Nicolas,Moraleda, Delphine,Santelli, Maurice
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body text
p. 5238 - 5240
(2009/12/06)
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- Toward selective functionalisation of oligosilanes: Borane-catalysed dehydrogenative coupling of silanes with thiols
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Among established methods for transforming Si-H bonds, carbonyl hydrosilylation and heterodehydrogenative coupling with alcohols catalysed by B(C6F5)3 are shown to provide exceptionally clean routes to the derivatisation of tetra-substituted disilanes such as [Ph2SiH]2, giving no products resulting from Si-Si bond cleavage. Even higher activity is observed for the borane-catalysed dehydrogenative coupling of silanes with alkyl- and arylthiols, the first examples of such Si-S bond formation in the absence of a transition metal catalyst. Clean, quantitative syntheses of a range of thiosilanes are reported, and the lability of the Si-S linkage toward subsequent alcoholysis is investigated. The crystal structure of 2,3-disila-2,2,3,3-tetramethyl-1,4- benzodioxane is presented.
- Harrison, Daniel J.,Edwards, David R.,McDonald, Robert,Rosenberg, Lisa
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p. 3401 - 3411
(2008/12/20)
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- Self-assembled monolayers of compact phosphanes with alkanethiolate pendant groups: Remarkable reusability and substrate selectivity in Rh catalysis
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(Chemical Equation Presented) Selective surface: A self-assembled monolayer consisting of a compact trialkylphosphane with an alkanethiolate pendant group was prepared on a gold surface. The rhodium complex of this system (see picture) showed high catalyt
- Hara, Kenji,Akiyama, Ryuto,Takakusagi, Satoru,Uosaki, Kohei,Yoshino, Toru,Kagi, Hiroyuki,Sawamura, Masaya
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scheme or table
p. 5627 - 5630
(2009/03/11)
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- Highly efficient O-silylation of alcohol with vinylsilane using a Rh(l)/HCl catalyst at room temperature
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Highly efficient O-silylation of alcohol with vinylsilane was developed using a catalyst system consisting of [(COE)2RhCl]2 and HCl. In this reaction, a key intermediate is chlorosilane, generated from vinylsilane and HCl, which can be regenerated in the catalytic cycle. Various alcohols and vinylsilanes were applied to the preparation of silyl ether compounds with this catalyst system.
- Park, Jung-Woo,Jun, Chul-Ho
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p. 4073 - 4076
(2008/02/11)
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- SURFACE MODIFIED ORGANIC·INORGANIC HYBRID GLASS, PROTECTING GROUP INDUCED ALCOHOL OR ITS DERIVATIVE AND PRODUCING METHOD THEREOF
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Disclosed are a protected alcohol or derivative thereof, a surface- modified organic-inorganic hybrid glass, and preparation methods thereof. More specifically, disclosed are a protected alcohol or derivative thereof and a surface-modified organic-inorganic hybrid glass, which are prepared by allowing a silane compound, having vinyl or a vinyl derivative, to react with an alcohol or derivative thereof or with an organic-inorganic hybrid glass, in the presence of an acid catalyst, a transition metal catalyst and an organic solvent, so as to introduce an organic group thereto even at room temperature, as well as preparation methods thereof. The disclosed invention allows a functional group to be effectively introduced into alcohol or a derivative thereof or into an organic-inorganic hybrid glass, not only high temperatures but also room temperature, and thus is highly effective in introducing compounds having a thermally sensitive functional group, for example, natural compounds or proteins. Also, the invention makes it possible to introduce various organic groups and to separate and purify organic macromolecule-bonded organosilane compounds using a silica gel column so as to effectively introduce large organic functional groups to inorganic materials. Accordingly, the invention is highly useful in the chemical industry.
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Page/Page column 13; 30-31; 1
(2010/11/28)
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- NEW PHARMACEUTICAL COMPOUNDS
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Compounds of formula (I), wherein R1-R4, X, Y and Z are as defined in claims, exhibit COMT enzyme inhibiting activity and are thus useful as COMT inhibitors.
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Page/Page column 40
(2008/06/13)
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- (4-PIPERIDINYL)-1H-2-BENZOPYRAN DERIVATIVES USEFUL AS ANTIPSYCHOTIC AGENTS
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The present invention comprises (4-Piperidinyl)-1H-2-Benzopyran derivatives useful as antipsychotic agents, their intermediates, pharmaceutical compositions and methods of making these compounds. These compounds are useful in treating psychosis.
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- An efficient and convenient method for preparation of 2,2-disubstituted and 2-monosubstituted 1,3-benzodioxoles from ketones and aldehydes with catechol catalysed by zro2/so42-
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The title compounds have been synthesised by reaction of catechol with ketones and aldehydes catalysed by ZrO2/SO42- solid superacid in high yields. Ketones gave better yields than aldehydes.
- Jin,Zhang,Wang,Guo,Li
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p. 289 - 291
(2007/10/03)
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- (4-PIPERIDINYL)-1H-2-BENZOPYRAN DERIVATIVES USEFUL AS ANTIPSYCHOTIC AGENTS
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The present invention comprises (4-Piperidinyl)-1H-2-Benzopyran derivatives useful as antipsychotic agents, their intermediates, pharmaceutical compositions and methods of making these compounds. These compounds are useful in treating psychosis.
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- Asymmetric Diels-Alder reaction of optically active 3-(3,3,3- trifluoropropenylsulfonyl)oxazolidine: Synthesis of (8R)8-trifluoromethyl-2- oxa-6-thia-5-azatricyclo[5.2.2.01,5]-undecane-6,6-dioxide
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Asymmetric Diels-Alder reaction of optically active 3-(3,3,3- trifluoropropenylsulfonyl)-1,3-oxazolidine (1) with several dienes gave adducts regio- and stereoselectively in 69 - 78% de. Acetalization of 2- methoxybutadiene adduct with catechol gave tricy
- Okano, Takashi,Nagai, Tomoyuki,Eguchi, Shoji,Kimoto, Hiroshi
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- Montmorillonite clay catalysis. Part 14. A facile synthesis of 2-substituted and 2,2-disubstituted 1,3-benzodioxoles
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A series of 2-substituted and 2,2-disubstituted 1,3-benzodioxoles have been synthesised by reaction of catechol and pyrogallol with corresponding aldehydes and ketones catalysed by montmorillonite KSF or K-10. The reactions are completed within 2.7-24 h to give satisfactory yields. Ketones give better yields than aldehydes, although highly sterically hindered ketones and diaryl ketones fail to react at all.
- Li, Tong-Shuang,Li, Li-Jun,Lu, Bo,Yang, Feng
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p. 3561 - 3564
(2007/10/03)
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- An Efficient Catalyst for the Conversion of Hydrosilanes to Alkoxysilanes
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The copper(I) hydride 6 is an efficient catalyst for the alcoholysis of primary and secondary silanes.The reactions proceed at room temperature within a few hours and give the alkoxysilanes in high yields.Only with bulky alcohols or silanes are longer reaction times and/or increased temperatures required.The presence of air accelarates the reactions and gives rise to higher yields of alkoxysilanes, particularly with bulky alcohols.Diols react with PhRSiH2 (R = Me, Ph) to afford 1,3-dioxo-2-silacycloalkanes and with tertiary silanes to furnish the bissilylated diols.When unsaturated alcohols (2-propen-1-ol or 2-propyn-1-ol) are employed, the double or triple bond is retained. - Keywords: Catalytic silane alcoholysis; Alkoxysilanes
- Lorenz, Catrin,Schubert, Ulrich
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p. 1267 - 1270
(2007/10/03)
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- Convenient route to di- and triorganosilyl ethyl ethers and the corresponding di- and triorganosilanes
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Tetraethoxysilane was treated with alkyl- and aryllithium reagents for the reparation of organosilyl ethyl ethers of the type R3SiOEt, R2R'SiOEt, and R2Si(OEt)2, that can be reduced to the organosilanes R3SiH, R2R'SiH, and R2SiH2, respectively, Compounds of the type RR'R''SiOEt cannot be cleanly formed.The reduction procedure involves treatment of the silyl alkoxy ethers with diisobutylaluminium hydride (DIBALH) and hydrolysis of the remaining alkylaluminium compounds with Na2SO4*10H2O.This hydrolysis provides a convenient method for the isolation of R3SiH, R2R'SiH, and R2SiH2 compounds without hydrolysis of the Si-H moiety that often occurs in standard aqueous work-up procedures of unhindered silanes.
- Tour, James M.,John, Jens A.,Stephens, Eric B.
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p. 301 - 310
(2007/10/02)
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- Conversion of hydrosilanes to alkoxysilanes catalyzed by Cp2TiCl2/nBuLi
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The combination of Cp2TiCl2 and nBuLi provides an effective catalyst for alcoholysis of the model silanes n-HexSiH3, PhMeSiH2, Ph2SiH2 and PhMe2SiH by ethanol, isopropanol, t-butyl alcohol and phenol.Increasing the steric bulk of the substituents on either the alcohol or the silane generally requires longer reaction periods and/or increasing temperature.All SiH bonds are converted to SiOEt groups by ethanol and a single SiH bond in secondary silanes and two SiH bonds in tertiary silanes are replaced by t-butyl alcohol.Diols including pinacol, 2,4-pentanediol and 2,5-hexanediol react with PhRSiH2 (R = Me, Ph) to give 1,3-dioxa-2-silacyclopentanes, -hexanes and -heptanes, respectively.Attempts to form caged structures by condensation of primary silanes and triols was unsuccessful.Hydrolysis of PhRSiH2 is promoted by Cp2TiCl2/n-BuLi and the siloxane is produced in quantitative yield when R = Ph and a mixture of linear disiloxanes and trisiloxanes in addition to cyclopolysilanes are produced when R = Me.Other protic reagents including acids, mercaptans, amines and enolizable ketones did not react.The effects of reaction parameters such as temperature, silane to catalyst ratio, solvent, transition metal and replacements for nBuLi were also determined.
- Bedard, Thomas C.,Corey, Joyce Y.
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p. 315 - 333
(2007/10/02)
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- Mechanism of Thermal Eliminations. Part 29. The Effect of Different Silyl groups upon Thermal Elimination of Ketene from Ethyl Silylacetates
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A series of ethyl silylacetates, R3SiCH2CO2Et where R3 = Me3, Me2Ph, MePh2, Ph3, have been prepared and their rates of gas-phase thermal elimination to ketene and the corresponding ethyl silyl ether measured, each over 50 deg C temperature range.Activation energies are in the range of 136-144 kJ mol-1, and log(A/s-1) values 10.1-10.8.Increase in the electrophilicity of silicon through replacement of one methyl group by phenyl produces a minor increase in reactivity, but further similar replacements eventually produce a rate decrease, which is attributed to steric hinderance.Overall the kinetic data indicate that the strength of the silicon-oxygen bond formed is sufficiently important that alteration in the ester structure is incapable of producing substantial variation in the rate of ketene formation.
- Chapman, Sara E.,Taylor, Roger
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p. 1119 - 1120
(2007/10/02)
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- Synthesis of compounds of interest in proton transfer spectroscopy
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A new series of compounds has been prepared for use in proton transfer spectroscopy. The complexes 6a-6d have been converted into the fully characterised perchlorates 7a-7d and the corresponding anhydro bases 8a-8d.
- Barton,Ozbalik,Sas
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p. 8043 - 8052
(2007/10/02)
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- A Novel Highly Stereoselective Synthesis of Tetrahydrodibenzo-1,4-dioxanes
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The cis- and trans-tetrahydrodibenzo-1,4-dioxanes 2 and 3 were synthesized from 2-bromocyclohexanone in five steps. - Key Words: Dichotomy in SN2 reactions / 1,4-Benzodioxanes, potential biological activity of
- Antus, Sandor,Baitz-Gacs, Eszter,Snatzke, Guenter,Toth, Tamas S.
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p. 1017 - 1020
(2007/10/02)
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