- Investigating the Structure and Reactivity of Azolyl-Based Copper(I)-NHC Complexes: The Role of the Anionic Ligand
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A family of copper(I)-NHC azolyl complexes was synthesized and deployed in the hydrosilylation of dicyclo-hexylketone to probe the role of the anionic ligand on catalytic performance. The azolyl ligand is shown to have a crucial role in catalytic activity
- Trose, Michael,Nahra, Fady,Poater, Albert,Cordes, David B.,Slawin, Alexandra M. Z.,Cavallo, Luigi,Cazin, Catherine S. J.
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- 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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- KF/clinoptilolite NPs: An efficient and heterogeneous catalyst for chemoselective silylation of alcohols and phenols
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Potassium fluoride incorporated on clinoptilolite nanoparticles (KF/CP NPs) by ion exchanging is found to be an effective and inexpensive heterogeneous nanocatalyst for chemoselective silylation of alcohols and phenols with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Nano-powder of clinoptilolite (CP) was prepared using a planetary ball mill mechanically method and characterized by dynamic light scattering (DLS), X-ray powder diffraction (XRD) and scanning electron microscope (SEM) analyses. Almost all of products were obtained in high yields as well as short reaction times and the catalyst was also reused eight times without loss of its catalytic activity.
- Oladee, Razieh,Zareyee, Daryoush,Khalilzadeh, Mohammad A.
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p. 731 - 737
(2021/03/31)
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- Silylation of Alcohols, Phenols, and Silanols with Alkynylsilanes – an Efficient Route to Silyl Ethers and Unsymmetrical Siloxanes
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The formation of several silyl ethers (alkoxysilanes, R3Si-OR') and unsymmetrical siloxanes (R3Si-O-SiR'3) can be catalyzed by the commercially available potassium bis(trimethylsilyl)amide (KHMDS). The reaction proceeds via direct dealkynative coupling between various alcohols or silanols and alkynylsilanes, with a simultaneous formation of gaseous acetylene as the sole by-product. The dehydrogenative and dealkenative coupling of alcohols or silanols are well-investigated, whilst the utilization of alkynylsilanes as silylating agents has never been comprehensively studied in this context. Overall, the presented system allows the synthesis of various attractive organosilicon compounds under mild conditions, making this approach an atom-efficient, environmentally benign, and sustainable alternative to existing synthetic solutions.
- Kuciński, Krzysztof,Stachowiak, Hanna,Hreczycho, Grzegorz
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p. 4042 - 4049
(2020/07/04)
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- Synthetic Versatility of Lipases: Application for Si-O Bond Formation and Cleavage
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Several commercially available lipases were examined in a study on O-Si bond formation and cleavage applying silicon-based protecting groups and alcohols or the corresponding silyl ethers. With regard to deprotection, from silyl ether to the corresponding alcohol, only the solvent and the lipase were necessary. The influence of the protecting group, the lipase source, and the substituent was investigated to optimize the results. The TMS moiety could be removed in 24 hours of reaction at room temperature in aqueous systems (conv. up to 99%, depending on the substrate and lipase). The reverse reactions, that is, with the protection of the alcohols, were carried out in hexane using different silyl chlorides. The TMS, TES, and TBS moieties were successfully inserted in the primary and secondary alcohols without the need for dry conditions or an inert atmosphere, presenting conversions of up to 99%, depending on the substrate.
- Brondani, Patrícia Bulegon,Mittersteiner, Mateus,Voigt, Morgana Aline,Klinkowski, Bruna Heloisa,Riva Scharf, Dilamara,De Jesus, Paulo Cesar
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supporting information
p. 477 - 485
(2019/01/10)
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- Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
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Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.
- Mashhadinezhad, Maryam,Shirini, Farhad,Mamaghani, Manouchehr
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p. 2099 - 2107
(2019/01/03)
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- A simple and efficient room temperature silylation of diverse functional groups with hexamethyldisilazane using CeO2 nanoparticles as solid catalysts
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In this study, a mild and efficient method is developed for the silylation of diverse functional groups using CeO2 nanoparticles (n-CeO2) as solid catalysts with hexamethyldisilazane (HMDS) as silylating agent at room temperature. Alcohols, phenols and acids are silylated to their respective silyl derivatives with faster reaction rate while amines and thiols required relatively longer reaction time. Moreover, the solid catalyst is easily be separated from the reaction mixture and recycled more than five times without any obvious decay in its activity. Powder X-ray diffraction (XRD), transmission electron microscope (TEM), UV–vis diffuse reflectance spectra (UV-DRS) and Raman analyses revealed identical structural integrity, particle size, absorption edge and valence state for the reused solid compared to the fresh solid catalyst.
- Anbu, Nagaraj,Vijayan, Chellappa,Dhakshinamoorthy, Amarajothi
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- FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
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Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
- Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
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p. 12356 - 12359
(2018/09/18)
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- Fast and efficient method for Silylation of alcohols and phenols with HMDS in the presence of bis-thiourea complexes of cobalt, nickel, copper and zinc chlorides
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Bis-thiourea complexes of cobalt, nickel, copper and zinc chlorides were used efficiently for rapid and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) in CH3CN. All reactions were carried out at room temperature within immediate-120?min timeframe to afford trimethylsilyl ether derivatives in high to excellent yields. Investigation of the results exhibited that the prepared bis-thiourea metal complexes show the activity as Co(tu)2Cl2> Ni(tu)2Cl2> Cu(tu)2Cl2> Zn(tu)2Cl2 in their silylation reactions.
- Zeynizadeh, Behzad,Sorkhabi, Serve
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p. 127 - 135
(2018/02/06)
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- Application of a novel nano-immobilization of ionic liquid on an MCM-41 system for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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3-[(3-(Trisilyloxy)propyl)chloride]-1-methylimidazolium tribromide ionic liquid supported on MCM-41 [nano-MCM-41@(CH2)3-1-methylimidazole]Br3 as a novel heterogeneous nano-catalyst was easily prepared and characterized usi
- Zolfigol, Mohammad Ali,Sajjadifar, Sami,Ghorbani-Choghamarani, Arash,Tami, Farzaneh
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p. 7093 - 7106
(2018/08/17)
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- Phase-Transfer Catalyzed O-Silyl Ether Deprotection Mediated by a Cyclopropenium Cation
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The use of a cyclopropenium cation as a phase-transfer catalyst for O-silyl ether deprotection is reported. Mechanistic insight into this deprotection methodology derived by linear free-energy relationships (LFER), quantum theory of atoms in molecules (QTAIM), and density functional theory (DFT) calculations are also provided.
- Mir, Roya,Dudding, Travis
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p. 709 - 714
(2017/04/26)
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- Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
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The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous iron catalysis were recorded by the isolation of novel Fe nanocluster architectures that act as catalyst reservoirs and soluble seeds of particle growth.
- Gieshoff, Tim N.,Chakraborty, Uttam,Villa, Matteo,Jacobi von Wangelin, Axel
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supporting information
p. 3585 - 3589
(2017/03/21)
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- Chlorozincate(II) acidic ionic liquid: Efficient and biodegradable silylation catalyst
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A practical and highly efficient silylation of alcohol and phenol derivatives with hexamethyldisilazane (HMDS) using acidic ionic liquids under mild reaction conditions is described. A series of Br?nsted as well as Br?nsted–Lewis acidic ionic liquids were prepared and their performance investigated for the silylation of a wide variety of alcohols and phenols with HMDS. Imidazole- as well as N-methyl-2-pyrrolidone-based acidic ionic liquids have a higher catalytic activity for the protection of sensitive, hindered alcohols and phenols, thus providing an environmentally begin and versatile alternative to current acid catalysts. In addition, the acidic ionic liquids are reusable, being recovered easily and reused several times without significant deterioration in catalytic activity.
- Abbasi, Faezeh,Azizi, Najmedin,Abdoli-Senejani, Masumeh
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- Room temperature silylation of alcohols catalyzed by metal organic frameworks
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The commercial Al(OH)(BDC) (BDC: 1,4-benzenedicarboxylic acid) metal organic framework (Basolite A100) is a suitable heterogeneous catalyst for the silylation of benzylic and aliphatic alcohols by hexamethyldisilazane in toluene at room temperature. Al(OH
- Dhakshinamoorthy, Amarajothi,Santiago-Portillo, Andrea,Concepción, Patricia,Herance, José R.,Navalón, Sergio,Alvaro, Mercedes,Garcia, Hermenegildo
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p. 2445 - 2449
(2017/07/24)
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- Rhodium-Catalyzed Dehydrogenative Silylation of Acetophenone Derivatives: Formation of Silyl Enol Ethers versus Silyl Ethers
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A series of rhodium–NSiN complexes (NSiN=bis (pyridine-2-yloxy)methylsilyl fac-coordinated) is reported, including the solid-state structures of [Rh(H)(Cl)(NSiN)(PCy3)] (Cy=cyclohexane) and [Rh(H)(CF3SO3)(NSiN)(coe)] (coe=cis-cyclooctene). The [Rh(H)(CF3SO3)(NSiN)(coe)]-catalyzed reaction of acetophenone with silanes performed in an open system was studied. Interestingly, in most of the cases the formation of the corresponding silyl enol ether as major reaction product was observed. However, when the catalytic reactions were performed in closed systems, formation of the corresponding silyl ether was favored. Moreover, theoretical calculations on the reaction of [Rh(H)(CF3SO3)(NSiN)(coe)] with HSiMe3and acetophenone showed that formation of the silyl enol ether is kinetically favored, while the silyl ether is the thermodynamic product. The dehydrogenative silylation entails heterolytic cleavage of the Si?H bond by a metal–ligand cooperative mechanism as the rate-determining step. Silyl transfer from a coordinated trimethylsilyltriflate molecule to the acetophenone followed by proton transfer from the activated acetophenone to the hydride ligand results in the formation of H2and the corresponding silyl enol ether.
- Garcés, Karin,Lalrempuia, Ralte,Polo, Víctor,Fernández-Alvarez, Francisco J.,García-Ordu?a, Pilar,Lahoz, Fernando J.,Pérez-Torrente, Jesús J.,Oro, Luis A.
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p. 14717 - 14729
(2016/10/03)
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- Preparation and characterization of a RHA/TiO2 nanocomposite: Introduction of an efficient and reusable catalyst for chemoselective trimethylsilyl protection and deprotection of alcohols and phenols
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In this work, rice husk ash (RHA), as a natural source of amorphous silica, was used as a support for the synthesis of anatase-phase titania nanoparticles leading to the RHA/TiO2 nanocomposite. This nanocomposite was used as an efficient catalyst for the chemoselective trimethylsilylation of various alcohols and phenols and deprotection of the obtained trimethylsilyl ethers. The procedure gave the products in excellent yields in very short reaction times. Also this catalyst can be reused at least six times without loss of its catalytic activity.
- Seddighi, Mohadeseh,Shirini, Farhad,Goli-Jolodar, Omid
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p. 23564 - 23570
(2016/03/12)
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- Introduction of PEG-SANM nanocomposite as a new and highly efficient reagent for the promotion of the silylation of alcohols and phenols and deprotection of the silyl ethers
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Poly (ethylene glycol)-sulfonated sodium montmorillonite (PEG-SANM) nanocomposite was prepared by a simple method and characterized using XRD, TGA, SEM, TEM, and FT-IR techniques. After preparation and characterization, this reagent was used as a highly efficient and reusable solid acid catalyst for the chemoselective silylation of alcohols and phenols and deprotection of the obtained silyl ethers. Themethod offers several advantages including high to excellent yields of the products, short reaction times, easy preparation of the catalyst and easy work-up procedure. In addition, the catalyst can be recycled and reused at least for five times without significant decrease in the catalytic activity.
- Shirini, Farhad,Shojaei, Abdollah Fallah,Heirati, Seyedeh Zahra Dalil
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p. 944 - 951
(2016/07/06)
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- First example of borirane synthesis by α-olefins reaction with BCl3·SMe2 Catalyzed with (η5-C5H5)2TiCl2
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New method was developed of the synthesis of 2-phenyl(alkyl, benzyl, phenoxy)-1-chloroboriranes via reaction of α-olefins with BCl3·SMe2 catalyzed by Cp2TiCl2. The method is based on the boracyclopropanes (boriranes) formation resulting from transmetallation of titanacyclopropanes arising from the reaction of α-olefins with Cp2TiCl2. The calculations were fulfilled of thermodynamic and activation parameters of possible reaction routes.
- Khusainova,Khafizova,Tyumkina,Dzhemilev
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p. 1517 - 1523
(2015/12/30)
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- Selective silylation of alcohols, phenols and oximes using N-chlorosaccharin as an efficient catalyst under mild and solvent-free conditions
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Efficient silylation of OH group in alcohols, phenols and oximes is described using a catalytic amount of N-chlorosaccharin and hexamethyldisilazane (HMDS) under mild and solvent-free conditions. This silylation reaction can be carried out with excellent and interesting various selectivities.
- Aghapour, Ghasem,Moghaddam, Ali Kazemi,Nadali, Samaneh
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p. 197 - 203
(2015/05/12)
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- USE OF CYCLOHEXA-2,5-DIEN-1-YL-SILANES AS PRECURSORS FOR GASEOUS HYDROSILANES
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The invention relates to the use of cyclohexa-2,5-dien-1 -yl-silanes of general formula (I), for generation of hydrosilanes in solution using a strong Lewis acid. This way, e.g., alkenes or carbonyl compounds can be hydrosilylated in good yields using the cyclohexa-2,5-dien-1 - yl-silanes of general formula I as transfer hydros! lylating agents in the presence of a strong Lewis acid as catalyst with concomitant formation of an arene solvent.
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Page/Page column 19; 20; 21
(2015/03/28)
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- Direct synthesis of a geminal zwitterionic phosphonium/hydridoborate system - developing an alternative tool for generating frustrated Lewis pair hydrogen activation systems
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A convenient way to a new class of geminal Mes2PH+/B(C6F5)2H- pairs is presented. It utilizes triflic acid addition to trans-Mes2PCHCHB(C6F5)2 fo
- Yu, Jiangang,Kehr, Gerald,Daniliuc, Constantin G.,Bannwarth, Christoph,Grimme, Stefan,Erker, Gerhard
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supporting information
p. 5783 - 5792
(2015/05/27)
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- Metal-free Lewis acid mediated dehydrocoupling of phosphines and concurrent hydrogenation
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The stoichiometric reaction of trityl cation with two equivalents of Ph2PH affords the phosphine stabilized phosphenium salt [Ph2(H)PPPh2][B(C6F5)4] via hydride abstraction, while catalytic amounts of B(p-HC6F4)3 effects catalytic phosphine dehydrocoupling with the liberation of H2. This reaction is accelerated by the presence of olefin or imine, effecting concurrent hydrogenation.
- Dobrovetsky, Roman,Takeuchi, Katsuhiko,Stephan, Douglas W.
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p. 2396 - 2398
(2015/02/05)
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- Iron-catalysed reduction of olefins using a borohydride reagent
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The iron-catalysed reduction of olefins has been achieved using a simple iron salt and sodium triethylborohydride. A wide range of mono- and trans-1,2-disubstituted alkenes have been reduced (91-100%) using 25 mol% iron(II) triflate, 1 mol% N-methyl-2-pyrrolidinone and 4 equivalents of sodium triethylborohydride. The reduction of alkynes to alkanes is also reported (up to 84%). Significantly, the reduction of trisubstituted alkenes has also been achieved (60-86%). Copyright
- Carter, Tom S.,Guiet, Lea,Frank, Dominik J.,West, James,Thomas, Stephen P.
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supporting information
p. 880 - 884
(2013/05/08)
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- {[[K.18-Crown-6]Br3}n: A tribromide catalyst for the catalytic protection of amines and alcohols
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{[K.18-Crown-6]Br3}n, a unique tribromide-type catalyst, was utilized for the N-boc protection of amines and trimethylsilylation (TMS) and tetrahydropyranylation (THP) of alcohols. The method is general for the preparation of N-boc derivatives of aliphatic (acyclic and cyclic) and aromatic, and primary and secondary amines and also various TMS-ethers and THP-ethers. The simple separation of the catalyst from the product is one of the many advantages of this method.
- Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Derakhshanpanah, Fateme
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p. 1730 - 1733
(2013/10/21)
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- Polystyrene-gallium trichloride complex: A mild, highly efficient, and recyclable polymeric lewis acid catalyst for chemoselective silylation of alcohols and phenols with hexamethyldisilazane
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Polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid effectively activates hexamethyldisilazane (HMDS) for the efficient silylation of alcohols and phenols at room temperature. In this he
- Rahmatpour, Ali,Vakili, Ali,Azizian, Setare
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p. 443 - 451
(2013/12/04)
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- [2.2] Paracyclophane derived bisphosphines for the activation of hydrogen by FLPs: Application in domino hydrosilylation/hydrogenation of enones
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The heterolytic splitting of hydrogen by two types of [2.2]paracyclophane derived bisphosphines (1, 2a and 2b) in combination with tris(pentafluorophenyl) borane (3) at room temperature is described. The corresponding frustrated Lewis pairs (FLPs) exhibit
- Greb, Lutz,Ona-Burgos, Pascual,Kubas, Adam,Falk, Florian C.,Breher, Frank,Fink, Karin,Paradies, Jan
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supporting information; experimental part
p. 9056 - 9060
(2012/09/08)
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- Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
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Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
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- P2O5/SiO2 as an efficient and mild catalyst for trimethylsilylation of alcohols using hexamethyldisilazane
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The protection of alcohols with hexamethyldisilazane (HMDS) in the presence of P2O5/SiO2 at very mild and ambient condition with short reaction times is accomplished in excellent yields. P 2O5/SiOsub
- Eshghi, Hossein,Rahimizadeh, Mohammad,Ghadamyari, Zohreh,Shiri, Ali
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p. 1435 - 1439
(2013/02/22)
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- Nanocrystalline TiO2-HClO4 as a new, efficient and recyclable catalyst for the chemoselective trimethylsilylation of alcohols, phenols and deprotection of silyl ethers
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TiO2-HClO4, as a new solid acid, was found to be an efficient catalyst for the chemoselective trimethylsilylation of alcohols and phenols. Deprotection of the resulting trimethylsilylethers was achieved using the same catalyst in methanol solvent. The synthesized catalyst was characterized by FT-IR, SEM, TEM, BET and XRD analyses. Our novel synthetic method has the advantages of high yields, short reaction times, low cost and recyclability of the catalyst, simplicity and easy work-up compared to the conventional methods reported in the literature.
- Shirini, Farhad,Atghia, Seyyed Vahid,Jirdehi, Mojtaba Ghazi
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- Poly(4-vinylpyridine) catalyzed chemoselective O-TMS protection of alcohols and phenols and N-Boc protection of amines
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Poly(4-vinylpyridine) (PVP) acts as an efficient and reusable catalyst for the selective and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and N-tert-butoxycarbonylation of amines with (Boc)2O. All reactions were performed under mild conditions in good to high yields. Iranian Chemical Society 2012.
- Shirini, Farhad,Khaligh, Nader Ghaffari
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p. 495 - 502
(2013/02/22)
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- H3PW12O40at the[bmim][FeCl4]: A green catalytic system for alkoxymethylation of alcohols and their one-pot interconversion to acetates and TMS-ethers
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12-Tungstophosphoric acid immobilized on [bmim][FeCl4] was found to be an efficient catalyst for chemoselective methoxymethylation and ethxoymethylation of alcohols and also one-pot conversion of MOM- or EOM-ethers to their corresponding acetates and TMS-ethers under thermal conditions and microwave irradiation. These procedures were simple, rapid and the corresponding products were obtained in high yields. The catalyst exhibited remarkable reactivity and was reusable.
- Mohammadpoor-Baltork,Moghadam,Tangestaninejad,Mirkhani,Khosropour,Mirjafari
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experimental part
p. 513 - 524
(2012/06/16)
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- [InCl4]: An efficient catalyst-medium for alkoxymethylation of alcohols and their interconversion to acetates and TMS-ethers
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A simple, green and chemoselective method for methoxymethylation and ethoxymethylation of primary and secondary alcohols using a Lewis acidic room temperature ionic liquid, [C4mim][InCl4], as catalyst and reaction medium under ambient temperature, microwave and ultrasonic irradiations is reported. In this catalytic system, the corresponding MOM-and EOM-ethers are obtained in excellent yields and in short reaction times. Furthermore, this catalytic system was used for mild and efficient transformations of these protected alcohols to their corresponding acetates and trimethylsilyl ethers under thermal conditions and microwave and ultrasonic irradiations.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Mirjafari, Arsalan
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experimental part
p. 568 - 579
(2012/05/05)
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- Sulfated zirconia: An efficient catalyst for solvent-free synthesis of silyl ethers under mild conditions
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Oximes, allylic, aliphatic, aromatic, cyclic, acyclic, and hetero alcohols are silylated in short reaction times with good yields in the midst of a catalytic amount of sulfated zirconia solid acid catalyst and trimethylsilyl cyanide under nonbasic, solvent-free, and ambient temperature conditions. Selectivity toward O-silyl ether rather than N-silyl ether has been observed. This simple experimental procedure, combined with easy recovery and reusability of the catalyst, is expected to contribute to the development of a clean and environmentally friendly strategy for the synthesis of O-silyl ethers. Copyright
- Thirupathi, Boningari,Prasad, Avvari N.,Srinivas, Rapelli,Reddy, Benjaram M.
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experimental part
p. 2064 - 2072
(2011/07/30)
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- Rapid and efficient trimethylsilyl protection of hydroxyl groups catalyzed by niobium(V) chloride
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An efficient and convenient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, and phenols with hexamethyldisilazane, has been developed. The reactions were carried out at room temperature in the presence of a catalytic amount of niobium(V) chloride and afforded the corresponding trimethylsilyl ethers in high to excellent yields in short time. Copyright Taylor & Francis Group, LLC.
- Hou, Jun-Tao,Chen, Hong-Li,Zhang, Zhan-Hui
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experimental part
p. 88 - 93
(2011/04/22)
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- Tetrabutylammonium phthalimide-N-oxyl: An efficient organocatalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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Tetrabutylammonium phthalimide-N-oxyl (TBAPINO) was found to be an effective organocatalyst for rapid, simple and chemoselective protection of the hydroxyl group of alcohols and phenols using hexamethyldisilazane (HMDS) under mild conditions. The low catalyst loading, high to quantitative yields and simple removal of the catalyst from the reaction mixture illustrate the other attractive features of this protocol.
- Dekamin,Yazdaninia,Mokhtari,Naimi-Jamal
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experimental part
p. 537 - 544
(2012/06/18)
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- Trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel
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An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, e
- Shaterian, Hamid Reza,Fahimi, Nafiseh,Azizi, Kobra
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experimental part
p. 1604 - 1611
(2011/10/05)
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- InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates
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A combined Lewis acid catalyst of InCl3 and Me3SiBr promoted the direct use of enol acetates in the coupling with low-reactive silyl ethers, in which functional groups including ketones and aldehydes survived. Sterically hindered silyl ethers such as ROSiEt3, ROSiPh3, ROSit-BuMe2, and ROSii-Pr3 were also applicable.
- Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 2762 - 2765
(2011/08/02)
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- Cross-linked poly(4-vinylpyridine/styrene) copolymer-supported bismuth(III) triflate: An efficient heterogeneous catalyst for silylation of alcohols and phenols with HMDS
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Cross-linked poly(4-vinylpyridine/styrene) copolymer-supported bismuth(III) triflate (30P/S-Bi) effectively activates hexamethyldisilazane (HMDS) for the silylation of alcohols and phenols. By the use of this heterogeneous catalytic system, a wide range of alcohols as well as phenols are converted into their corresponding trimethylsilyl ethers in high yield under mild reaction conditions. The catalyst was reused more than 10 times without significant loss of its catalytic activity.
- Lee, Sang-Hyeup,Kadam, Santosh T.
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experimental part
p. 608 - 615
(2011/11/12)
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- Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
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New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, 1H NMR and 13C NMR studies. All the products were extensively characterized by 1H NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Khaligh, Nader Ghaffari
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experimental part
p. 63 - 70
(2011/12/02)
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- Succinimide-N-sulfonic acid: A mild, efficient, and reusable catalyst for the chemoselective trimethylsilylation of alcohols and phenols
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Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields. Copyright Taylor & Francis Group, LLC.
- Shirini,Khaligh, Nader Ghaffari
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experimental part
p. 2156 - 2165
(2012/04/10)
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- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalysed by in situ generated I2 using Oxone /KI or cerium ammonium nitrate (CAN)/KI systems under mild conditions
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Structurally diverse alcohols and phenols were trimethylsilylated in clean and efficient reactions with hexamethyldisilazane (HMDS) in the presence of a catalytic amount of I2 generated in situ from Oxone /KI or CAN/KI systems. The reactions occur rapidly in good to high yields in wet CH2Cl2 at room temperature. Indian Academy of Sciences.
- Kolvari, Eskandar,Khazaei, Ardeshir,Zolfigol, Mohammad Ali,Koukabi, Nadiya,Gilandoust, Maryam,Bakhit, Neda
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experimental part
p. 703 - 708
(2012/07/14)
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- [H2-Cryptand 222]2+(Br3-) 2 as a tribromide-type catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols
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A stable organic tribromide, [H2-cryptand 222] 2+(Br3-)2 was utilized as an active catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols.
- Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Khakyzadeh, Vahid,Gholami, Hadi,Niknam, Khodabakhsh
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experimental part
p. 127 - 131
(2012/06/18)
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- Electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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In the present work, the application of electron-deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Taghavi, S. Abdolmanaf
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experimental part
p. 687 - 694
(2012/01/06)
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- A new crystal engineering approach for the synthesis of {[K.18-Crown-6]I3}n as a nanotube-like and recyclable catalyst for the chemoselective silylation of alcohols
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Reaction of 18-crown-6 with KI in ethanol solution followed by addition of iodine (I2) afforded a unique triiodide salt with a nanotube-like structure ({[K.18-Crown-6]I3}n). It is shown that this reagent may be used for the chemoselective trimethylsilylation of alcohols. The synthesis of the crystalline reagent is a good example of crystal engineering. Reagent was recycled and reused.
- Zolfigol,Kolvari,Koukabi,Salehzadeh,Chehardoli,Tidmarsh,Niknam
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experimental part
p. 484 - 494
(2012/06/18)
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- Microwave-assisted rapid and efficient deprotection and direct esterification and silylation of MOM and EOM ethers catalyzed by [Hmim][HSO 4] as a Bronsted acidic ionic liquid
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1-Methylimidazolium hydrogensulfate, [Hmim] [HSO4], a Bronsted acidic room temperature ionic liquid, is used as a catalyst and reaction medium for facile and ecofriendly deprotection of methoxymethyl (MOM) and ethoxymethyl (EOM) ethers to their corresponding alcohols under thermal conditions (Δ) and microwave irradiation (MW). Furthermore, one-pot interconversion to the respective acetates and trimethylsilyl (TMS) ethers was also achieved. Springer-Verlag 2010.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Mirjafari, Arsalan
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experimental part
p. 1083 - 1088
(2012/06/18)
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- An expeditious, efficient green methodology for the Boc protection of amines and silyl protection of alcohols over tungstophosphoric acid-doped mesoporous silica
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An efficient, chemoselective and eco-friendly protocol for the protection of amines as N-tert-butylcarbamate using (Boc)2O and protection of alcohols as silyl ether using HMDS over tungstophosphoric acid/SBA15 has been developed. Solventless condition, easy work-up, short reaction time, excellent yields and reusability of the catalyst are the striking features of this methodology which can be considered to be one of the better methods for the protection of amines and alcohols.
- Karmakar, Bikash,Banerji, Julie
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experimental part
p. 3855 - 3858
(2010/08/20)
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- Boric acid as cost-effective and recyclable catalyst for trimethylsilyl protection and deprotection of alcohols and phenols
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Boric acid has been used as a green, selective and recyclable catalyst for trimethysilylation of alcohols and phenols using hexamethyldisilazane in acetonitrile. Deprotection of trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. The salient features of this methodology are cheap processing, mild acidity conditions, excellent yields of products and easy availability of the catalyst.
- Rostami, Amin,Akradi, Jamal,Ahmad-Jangi, Firoz
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experimental part
p. 1587 - 1592
(2010/11/04)
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- Silica-bonded S-sulfonic acid as a recyclable catalyst for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS)
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Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in tert-butylmethyl ether, and used as a catalyst for the silylation of hydroxyl groups. A good range of primary, secondary alcohols
- Niknam, Khodabakhsh,Saberi, Dariush,Molaee, Hajar,Zolfigol, Mohammad Ali
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experimental part
p. 164 - 171
(2010/04/04)
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- Green and efficient procedure for the trimethylsilylation of hydroxy groups and their regeneration using sulfamic acid as recyclable catalyst
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Structurally diverse alcohols and phenols were efficiently transformed into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of sulfamic acid (SA) at room temperature under both acetonitrile and solvent-free conditions. Deprotection of these trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. Copyright Taylor & Francis Group, LLC.
- Rostami, Amin,Ahmad-Jangi, Firoz,Zarebin, Mohammad Rezgar,Akradi, Jamal
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experimental part
p. 1500 - 1507
(2010/07/15)
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- Silylation of alcohols and phenols using hexamethyldisilazane catalyzed by N,N'-diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) under solvent-free and microwave conditions
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N,N'-Diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) (NIBTS) is an effective catalyst for the silylation of alcohols and phenols using hexamethyldisilazane under solvent-free and microwave conditions. Supplemental materials are available for this art
- Ghorbani-Vaghei, Ramin,Malaekehpoor, Seyedeh Mina
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experimental part
p. 582 - 587
(2010/06/15)
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