- Formation of 1-aza-2-silacyclopentanes and unexpected products from the insertion of phenylisocyanate into 2,2-dimethyl-1-(trimethylsilyl)-1-aza-2-silacyclopentane
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Substances like 3-aminopropyltriethoxysilane are often used as adhesive promoters in various formulations for coatings or to adjust the properties of siloxanes and other polymers. Cyclisation of similar substances is also interesting because of the formation of the Si-N bond. 1-Aza-2-silacyclopentanes were synthesised from 3-aminopropylalkoxysilanes by intramolecular condensation reactions and substitution reactions at the silicon atom. The products tend to undergo ring-opening polymerisation. In contrast to literature reports, they can only be isolated as N-substituted derivatives. Phenylisocyanate inserts into the Si-N bonds of cyclic aminosilanes to form seven-membered heterocycles. Furthermore, phenylisocyanate reacts with N-H bonds in the same molecule. Two insertion products were isolated, and their crystal structures were determined.
- Herbig, Marcus,B?hme, Uwe,Schwarzer, Anke,Kroke, Edwin
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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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- Alum: An efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence of alum as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected in CH3CN under mild conditions.
- Yang, Xiaojuan,Liang, Jinying
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experimental part
p. 228 - 230
(2012/08/07)
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- Melamine-trisulfonic-acid-catalyzed trimethylsilylation of alcohols and phenols
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A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence ofmelamine trisulfonic acid as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected under solvent-free conditions. Copyright Taylor & Francis Group, LLC.
- Wu, Liqiang,Sun, Pengli,Yan, Fulin
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experimental part
p. 2055 - 2060
(2011/11/30)
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- Silylation of alcohols and phenols with hexamethyldisilazane over highly reusable propyl sulfonic acid functionalized nanostructured SBA-15
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Various alcohols and phenols were trimethylsilylated in excellent yields using hexamethyldisilazane in the presence of catalytic amounts of environmentally friendly, hydrophobic, highly thermal stable, and completely heterogeneous sulfonic acid functionalized mesostructured SBA-15 in dichloromethane at ambient temperature. Primary, bulky secondary, tertiary, and phenolic hydroxyl functional groups were transformed to the corresponding trimethylsilyl ethers in excellent yields. The simple experimental procedure was accompanied by easy recovery and the catalyst was reusable (at least 18 reaction cycles); these are attractive features of this protocol.
- Zareyee, Daryoush,Asghari, Rezvaneh,Khalilzadeh, Mohammad A.
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experimental part
p. 1864 - 1868
(2012/02/16)
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- Sulfonated ordered nanoporous carbon (CMK-5-SO3H) as an efficient and highly recyclable catalyst for the silylation of alcohols and phenols with hexamethyldisilazane (HMDS)
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An environmentally friendly catalytic system for trimethylsilylation of alcohols and phenols with hexamethyldisilazane can be successfully carried out for the first time over sulfonated mesoporous carbon catalyst (CMK-5-SO 3H) in dichloromethane at ambient temperature and excellent conversions were obtained. Furthermore, the catalyst displays high activity and thermal stability (to 200 °C) and it can be reused repeatedly for at least 25 cycles without any evidence of loss of activity, confirming the stability of covalent bonding of acidic centers.
- Zareyee, Daryoush,Ghandali, Mohammad S.,Khalilzadeh, Mohammad A.
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experimental part
p. 1521 - 1525
(2012/06/18)
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- Chemoselective and catalytic trimethylsilylation of alcohols and phenols by 1,1,1,3,3,3-hexamethyldisilazane and catalytic amounts of PhMe 3N+Br3-
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An efficient procedure for the trimethylsilylation of alcohols and phenols is presented. The combination of 1,1,1,3,3,3-hexamethyldisilazane and a catalytic amount of phenyltrimethylammonium tribromide (PhMe3N +Br3-) was found to be effective for the trimethylsilylation of alcohols and phenols. The protection reaction is very simple and homogenously performed in dichloromethane at room temperature and mild conditions.
- Ghorbani-Choghamarani, Arash,Cheraghi-Fathabad, Nasrin
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experimental part
p. 1103 - 1106
(2010/12/25)
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- Protection of hydroxy groups as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyldisilazane (HMDS) catalyzed BY poly(4-VINYLPYRIDINIUM TRIBROMIDE)
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A very efficient procedure for the protection of alcohols and phenols is presented. The mixture of 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and catalytic amounts of poly(4-vinylpyridinium tribromide) was found to be effective for the trimethylsilylation of
- Ghorbani-Choghamarani, Arash,Zolfigol, Mohammad Ali,Hajjami, Maryam,Darvishi, Khorshid,Gholamnia, Laleh
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experimental part
p. 607 - 615
(2011/08/05)
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- Trimethylsilylation of alcohols and phenols, and direct acetylation of silyl ethers catalyzed by Fe(ClO4)3.6H2O
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In this article, a mild and efficient protocol for the trimethylsilylation of various aliphatic and benzylic alcohols and phenols with trimethylsilyl chloride using a catalytic amount of ferric perchlorate at room temperature and relatively short reaction times in good to excellent yields is reported. Direct acetylation of trimethylsilyl ethers catalyzed with Fe(ClO4)3.6H2O(0.02 mmol)/Fe(ClO4)3SiO2(0.2 g) using acetic anhydride at ambient temperature is also reported.
- Oskooie, Hossein A.,Heravi, Majid M.,Tehrani, Maryam H.,Behbahani, Farahnaz K.,Heravi, Omid M.
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experimental part
p. 1729 - 1737
(2010/01/17)
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- 1,3-Dichloro-5,5-dimethylhydantoin (DCH) and trichloromelamine (TCM) as efficient catalysts for the chemoselective trimethylsilylation of hydroxyl group with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) under mild conditions
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A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence of 1,3-dichloro-5,5-dimethylhydantoin (DCH) and/or trichloromelamine (TCM) as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected in CH2Cl2/CH3CN under mild conditions.
- Ghorbani-Choghamarani, Arash,Amani, Kamal,Zolfigol, Mohammad Ali,Hajjami, Maryam,Ayazi-Nasrabadi, Roia
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experimental part
p. 255 - 260
(2009/12/06)
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- Trimethylsilylation of hydroxyl group with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) catalyzed by tribromomelamine (TBM)
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Tribromomelamine (TBM) can be used as a novel catalyst for the trimethylsilylation of alcohols and phenols with 1,1,1,3,3,3- hexamethyldisilazane (HMDS). A wide variety of hydroxyl groups were selectively protected in CH2Cl2/CH3CN under mild conditions.
- Ghorbani-Choghamarani, Arash,Zolfigol, Mohammad Ali,Hajjami, Maryam,Jafari, Shila
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experimental part
p. 1208 - 1213
(2010/01/07)
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- A novel efficient method for the silylation of alcohols using hexamethyldisilazane in an ionic liquid
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Benzylic and primary alcohols were protected by hexamethyldisilazane in good to excellent yields at r.t. in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) ionic liquid. In addition, the ionic liquid was recovered quantitatively and reused efficiently in the next reactions. The protocol was successfully applied to the protection of phenols. Copyright Taylor & Francis Group, LLC.
- Mojtahedi, Mohammad M.,Abbasi, Hassan,Abaee, M. Saeed
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p. 1541 - 1544
(2007/10/03)
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- Synthesis of Trimethylsilyloxy and Hydroxy Compounds from Carbanions and Bis(trimethylsilyl)peroxide.
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The reactions of bis(trimethylsilyl)peroxide with alkyl, vinyl, alkynyl, aromatic and heteroaromatic anions are described.Depending on the reaction conditions, the trimethylsilyloxy derivatives can be obtained alone or together with the corresponding trimethylsilyl derivatives, which is sometimes the major product.Enolates, generated using magnesium diisopropylamide give the corresponding hydroxycarbonyl compounds in good yields.An attempt to rationalise the above results is given, emphasising the wide use of bis(trimethylsilyl)peroxide in organic synthesis as an electrophilic hydroxylation reagent.
- Camici, Lucia,Dembech, Pasquale,Ricci, Alfredo,Seconi, Giancarlo,Taddei, Maurizio
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p. 4197 - 4206
(2007/10/02)
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- Reactivity of the Labile Silaethene Me2Si=C(SiMe3)2, Stored as Ph2C=NSiMe3 Adducts
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Silaethene Me2Si=C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 deg C as a reaction intermediate, combines with reactants a-b (e.g.HO-H, RO-H, RCOO-H, RS-H, RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g.O=CPh2, Me3SiN=CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g.RN=N=N, O=N=N), a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under -, - as well as -c ycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene, 2,3-dimethylbutadiene, acetone) under ene reaction.According to relative reaction rates, insertion and -cycloadditions seem to proceed in two reaction steps, whereas -cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions.For reactivities cf.Table I. - Key words: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Relative Reactivities
- Wiberg, N.,Preiner, G.,Wagner, G.,Koepf, H.
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p. 1062 - 1074
(2007/10/02)
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