- Activation of hexamethyldisilazane (HMDS) by TiO2 nanoparticles for protection of alcohols and phenols: the effect of the catalyst phase on catalytic activity
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Anatase TiO2 nanoparticles (TiO2 NPs) were synthesized by the sol–gel method using titanium tetra-isopropoxide (TTIP), isopropyl alcohol, and distilled water and then calcined at 400?°C for 3?h. X-ray diffraction and scanning electron microscopy methods, and Fourier transform infrared spectroscopy were used for characterization of the obtained TiO2 NPs. The obtained anatase TiO2 NPs were used as heterogeneous catalyst for trimethylsilation of various alcohols or phenols with hexamethyldisilazane (HMDS) in CH3CN at room temperature. High to quantitative yields of the products were obtained within short reaction times at room temperature using a very low loading of pure TiO2 NPs without any post-modification with Bronsted or Lewis acid species such as ClSO3H or HClO4. The catalyst can be recycled at least three times without significant loss of its activity. The results of this study provide evidence that the pure anatase phase of TiO2 exhibits higher catalytic activity in terms of catalyst loading and required reaction time compared to a mixture of anatase and rutile phases found in the commercial samples for trimethylsilation of various alcohols or phenols with HMDS.
- Azad, Alireza,Dekamin, Mohammad G.,Afshar, Shahrara,Tadjarodi, Azadeh,Mollahosseini, Afsaneh
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p. 2951 - 2963
(2018/04/11)
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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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- Nano Fe3O4@ZrO2/SO42?: A highly efficient catalyst for the protection and deprotection of hydroxyl groups using HMDS under solvent-free condition
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In this work, we introduce a new procedure for the protection and deprotection process of various types of alcohols and phenols by HMDS in the presence of nano magnetic sulfated zirconia (Fe3O4@ZrO2/SO42?) as a solid acid catalyst under very mild and solvent-free condition. This method has interesting advantages like short reaction times and a simple workup process. With regard to some outstanding benefits of this new heterogeneous catalyst such as excellent yield, reusability of the catalyst and easy thermal stability, high acidity, strong and excellent magnetic properties, this method can be very interesting in aspect of green chemistry Principles.
- Ghafuri, Hossein,Paravand, Fatemeh,Rashidizadeh, Afsaneh
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supporting information
p. 129 - 135
(2016/12/24)
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- P4VPy–CuO nanoparticles as a novel and reusable catalyst: application at the protection of alcohols, phenols and amines
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P4VPy–CuO nanoparticles were synthesized using ultrasound irradiations. Relevant properties of the synthesized nanoparticles were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. After identification, the prepared reagent was used for the promotion of different types of protection reactions of alcohols, phenols and amines. Easy workup, short reaction times, excellent yields, relatively low cost and reusability of the catalyst are the striking features of the reported methods.
- Shirini, Farhad,Fallah-Shojaei, Abdollah,Abedini, Masoumeh,Samavi, Laleh
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p. 1699 - 1712
(2016/07/27)
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- Preparation of nano silica supported sodium hydrogen sulfate: As an efficient catalyst for the trimethyl, triethyl and t-butyldimethyl silylations of aliphatic and aromatic alcohols in solution and under solvent-free conditions
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Nano silica supported sodium hydrogen sulfate has been prepared by mixing NaHSO4 with activated Nano silicagel. We wish to report a new method for the synthesis of trimethyl (TMS), triethyl (TES) and t-butyldimethyl silyl (TBS) ethers from benzylic, allylic, propargylic alcohols, phenols, naphtholes and some of phenolic drugs in the solution and under solvent-free conditions.
- Abri, Abdolreza,Ranjdar, Somayeh
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p. 929 - 934
(2014/10/16)
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- DIHYDROPYRROLONES AND THEIR USE AS ANTIMICROBIAL AGENTS
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The present invention relates generally to antimicrobial dihydropyrrolone compounds, methods for their use and methods for preparing surfaces to which the dihydropyrrolone compounds are attached.
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Page/Page column 29
(2014/12/12)
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- Tributyltin grafted onto the surface of 3-aminopropyl functionalized γ-Fe2O3 nanoparticles: A magnetically-recoverable catalyst for trimethylsilylation of alcohols and phenols
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Bonding of a homogenous tributyltin chloride catalyst on the surface of functionalized magnetic nanoparticles provides a new stable, efficient and magnetically recyclable catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazan un
- Nikbakht, Fatemeh,Ghonchepour, Ehsan,Ziyadi, Hakimeh,Heydari, Akbar
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p. 34428 - 34434
(2014/10/15)
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- A mild and highly efficient method for the preparation of silyl ethers using Fe(HSO4)3/Et3N by chlorosilanes
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Avery efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t-buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO 4)3/Et3N in roomtemperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols.
- Abri, Abdolreza,Assadi, Mohammad Galeh,Pourreza, Samira
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p. 1449 - 1454
(2013/03/13)
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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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- PREPARATION OF BENZOFURANS AND USE THEREOF AS SYNTHETIC INTERMEDIATES
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The present invention provides several synthetic methods for preparing N-(2-butylbenzofuran-5-yl)-N-(methylsulfonyl)methanesulfonamide, a compound of formula (3), an intermediate in the preparation of Dronedarone. The present invention further provides a process for preparing Dronedarone, comprising the steps of converting 2-butyl-5-bis(methanesulfon)-amidobenzofuran of formula (3) to Dronedarone, wherein the 2-butyl-5-bis(methanesulfon)-amidobenzofuran of formula (3) is prepared by the processes of the present invention.
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Page/Page column 29
(2011/09/15)
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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 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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- 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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- Promoting the formation and stabilization of human telomeric G-quadruplex DNA, inhibition of telomerase and cytotoxicity by phenanthroline derivatives
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Four new di-substituted phenanthroline-based compounds a-d have been designed and prepared, and they have been shown to induce the formation of anti-parallel structure of human telomeric G-quadruplex DNA by CD spectra. FRET assay indicates that the melting temperature increases (ΔTm values) of G-quadruplex in buffer (pH 7.4) containing 100 mM NaCl are 31.6, 34.6, 17.8 and 32.6°C for the compounds (1.0 μM) a, b, c and d, respectively. Competitive FRET assay shows that the four compounds exhibit a high G-quadruplex DNA selectivity over duplex DNA. Three of the compounds are the potent telomerase inhibitors and HeLa cell proliferation inhibitors.
- Wang, Lihua,Wen, Ye,Liu, Jie,Zhou, Jun,Li, Can,Wei, Chunying
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scheme or table
p. 2648 - 2653
(2011/05/15)
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- Magnesium hydrogensulfate [Mg(HSO4)2] as an efficient catalyst for the preparation of silyl ethers, dibenzo[a,j]xanthenes, and octahydroxanthene derivatives
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Magnesium hydrogensulfate [Mg(HSO4)2], as a heterogeneous solid acid catalyst, has been used for the mild formation of trimethylsilyl (TMS) ethers from various primary, secondary, and tertiary aliphatic alcohols; aromatic alcohols; a
- Shaterian, Hamid Reza,Doostmohammadi, Razieh,Khorami, Fahimeh,Ghashang, Majid
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experimental part
p. 171 - 180
(2010/04/05)
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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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- A Facile and efficient trimethylsilylation of hydroxyl groups using silica-supported zinc chloride and alumina-supported sodium hydrogensulfate as recyclable heterogeneous catalysts
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Silica-supported zinc chloride (SiO2-ZnCl2) and novel alumina-supported sodium hydrogensulfate (NaHSO4-Al 2O3) as recyclable heterogeneous catalysts have been used for the mild trimethylsilylation of hydroxyl groups under ambient conditions. This procedure also allows for the selective protection of primary and secondary alcohols in the presence of tertiary alcohols.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Doostmohammadi, Razieh,Amirzadeh, Azita,Ghashang, Majid
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experimental part
p. 2227 - 2237
(2010/04/25)
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- Preparation of silica supported tin chloride: As a recyclable catalyst for the silylation of hydroxyl groups with HMDS
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Silica-supported tin chloride [SiO2-Sn(Cl)4-n] has been prepared by mixing tin chloride with activated silica gel in toluene under refluxing conditions for one day. Arange of primary, secondary, and tertiary alcohols as well as phenolic hydroxyl groups were converted into their corresponding trimethylsilyl ethers with hexamethyldisilazane in the presence of catalytic amounts of silica-supported tin chloride at room temperature. An excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups was also observed. This catalyst could be recycled and reused fifteen times without loss of efficiency.
- Niknam, Khodabakhsh,Zolfigol, Mohammad Ali,Saberi, Dariush,Molaee, Hajar
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experimental part
p. 1257 - 1264
(2010/08/19)
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- Silica triflate as a new, efficient, and reusable reagent for the chemoselective silylation of alcohols and phenols and deprotection of silyl ethers
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Silica triflate was easily prepared via reaction of silica gel and trifluoromethane sulfonyl chloride at room temperature. This compound can be employed as an efficient and reusable reagent for the chemoselective silylation of alcohols and phenols in solution and under solvent-free conditions. This reagent also effectively catalyzed the deprotection of silyl ethers in refluxing methanol.
- Shirini,Marjani,Nahzomi, H. Taherpour,Zolfigol
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p. 168 - 177
(2008/12/22)
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- A highly efficient method for the silylation of alcohols, phenols, and naphthols using HMDS in the presence of zinc oxide (ZnO) as economical heterogeneous catalyst
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Variety alcohols, phenols, and naphthols were effectively converted into their corresponding trimethylsilyl ether with hexamethyldisilazane in the presence of zinc oxide under very mild and ambient conditions with short reaction time in good to excellent yields.
- Shaterian, Hamid Reza,Ghashang, Majid
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p. 194 - 204
(2008/12/21)
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- An efficient method for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS) catalyzed by aluminum tris(dihydrogen phosphate) under solvent-free and ambient conditions
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A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS), using Al(H2PO4)3 as a recyclable heterogeneous catalyst at room temperature in a few minutes with excellent yields under solvent-free conditions is described.
- Shaterian, Hamid Reza,Ghashang, Majid,Riki, Nassrin Tajbakhsh,Asadi, Manijeh
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p. 841 - 845
(2008/12/20)
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- Alumina sulfuric acid as an efficient and recyclable heterogeneous catalyst for the O-silylation of alcohols, phenols, and oximes
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Alumina sulfuric acid as a recyclable catalyst conducts the transformation of various types of alcohol, phenols, and oximes with hexamethyldisilazane (HMDS) to the corresponding O-trimethylsilylated compounds in good to excellent yields under mild and ambient conditions with short reaction times. The method is highly selective for the conversion of primary alcohols in the presence of secondary and tertiary alcohols. Additionally, the catalyst can be easily recovered and reused at least eight times without detectable loss of reactivity.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Amirzadeh, Azita,Ghashang, Majid,Hosseinian, Asghar
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scheme or table
p. 2584 - 2595
(2009/08/15)
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- Silica-supported ferric chloride (silica-FeCl3): A reusable, easily controllable catalyst for the protection of hydroxyl groups under mild and ambient conditions
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Diverse alcohols, phenols, and naphthols were converted into their corresponding trimethylsilyl ether effectively with hexamethyldisilazane in the presence of silica-FeCl3 under solvent-free and ambient conditions with short reaction time in good to excellent yields. Work up procedure is easy, and the catalyst can be recovered by simple filtration and reused. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Ghashang, Majid,Hosseinian, Asghar
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experimental part
p. 2108 - 2118
(2009/07/18)
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- Alumina perchloric acid (Al2O3-HClO4) as an efficient heterogeneous catalyst for modified preparation of trimethylsilyl ethers
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A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS) using alumina perchloric acid (Al2O3-HClO4) as recyclable heterogeneous catalyst in excellent yields with short reaction times (3-65 min) under ambient conditions is described. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Amirzadeh, Azita,Ghashang, Majid
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experimental part
p. 2865 - 2874
(2009/09/25)
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- Simple and practical protocol for the silylation of phenol derivatives using reusable NaHSO4 dispread on silica gel under neutral conditions
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A simple and mild procedure for the trimethylsilylation of a wide variety of phenols with hexamethyldisilazane (HMDS) on the surface of silica gel dispersed with NaHSO4 at r.t. in a few minutes with excellent yields under neutral conditions is
- Khalili, Mahideh S.,Ghafuri, Hossein,Mojahedi-Jahromi, Samaneh,Hashemi, Mohammed M.
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p. 175 - 179
(2007/10/03)
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- Rh(I)-catalyzed O-silylation of alcohol with vinylsilane
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Silyl ethers can be produced from alcohols and vinylsilanes under a rhodium(I) catalyst. The reaction is believed to proceed through an O-H bond cleavage of alcohol by rhodium(I) complex and a subsequent hydride insertion into vinylsilane followed by β-silyl elimination of the resulting β-silylethyl rhodium(III) complex. Georg Thieme Verlag Stuttgart.
- Park, Jung-Woo,Chang, Hoon-Jo,Jun, Chul-Ho
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p. 771 - 775
(2007/10/03)
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- Efficient and practical protocol for silylation of hydroxyl groups using reusable lithium perchlorate dispread in silica gel under neutral condition
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A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups.
- Azizi, Najmedin,Yousefi, Rozbeh,Saidi, Mohammad R.
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p. 817 - 820
(2007/10/03)
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- Chemoselective protection of hydroxyl groups and deprotection of silyl ethers
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Trimethylsilylation of alcohols and phenols is carried out using hexamethyldisilazane and LiClO4 under microwave irradiation and neutral conditions. The deprotection of silyl ethers is carried out similarly using natural kaolinitic clay and a few drops of water.
- Bandgar,Kasture
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p. 1101 - 1104
(2007/10/03)
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- A study of ortho- and para-siloxyanilines for the synthesis of mono-, bi-, and tetra-nuclear early transition metal-imido complexes
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The siloxyanilines o-Me3SiOC6H4NH2 (1) and p-RMe2SiOC6H4NH2 (R = H (2); R = Me (3)), and their N-silylated derivatives p-Me3SiOC6H4NHS
- Benito,Arévalo, Silvia,De Jesús,De La Mata,Flores,Gómez
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- Process for the preparation of isocyanates and their use for the preparation of polyisocyanates containing ester
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This invention relates to a novel process for the preparation of isocyanates containing silylated alcoholic or phenolic hydroxyl groups as substituents and to the use of the compounds obtained by this process as reactants for isocyanatocarboxylic acid halides in the preparation of polyisocyanates containing ester groups.
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- A Simple and Versatile Synthesis of Trimethylsiloxy-Substituted Isocyanates
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A versatile and efficient method for the synthesis of trimethylsiloxy-substituted isocyanates without the use of carbonyl chloride consists of the reaction of the O-trimethylsilyl derivatives of aminoalcohols, aminophenols, 4-aminobenzoic acid, and hydrox
- Mormann, Werner,Leukel, Gabriele
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p. 990 - 992
(2007/10/02)
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