- Nitrogen ligand complexes of metal chlorides as effective catalysts for the highly regio- and chemoselective silylation of hydroxyl groups with hexamethyldisilazane (HMDS) at room temperature
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Zn(bipy)3Cl2, Fe(bipy)Cl3, and Fe(tpp)Cl are effective catalysts for silylation of hydroxy groups with HMDS at room temperature in dry CH3CN. High selectivity is observed between primary and secondary hydroxy fu
- Firouzabadi,Sardarian,Khayat,Karimi,Tangestaninejad
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- A mild and efficient method for chemoselective silylation of alcohols using hexamethyldisilazane in the presence of silica chloride
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Reaction of alcohols with hexamethyldisilazane in the presence of silica chloride provides efficiently the corresponding trimethylsilyl ethers. This system discriminates absolutely amines and thiols from alcohols.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Mohammadi, Kamal
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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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- Lanthanum trichloride: An efficient catalyst for the silylation of hydroxyl groups by activating hexamethyldisilazane (HMDS)
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A variety of hydroxy functional groups was protected as their corresponding trimethylsilyl ethers using HMDS in the presence of lanthanum trichloride. The catalyst LaCl3 activates the HMDS and accelerates the reaction under mild reaction conditions at room temperature to afford the corresponding silylated products in excellent yields.
- Narsaiah, Akkirala Venkat
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- Trimethylsilylazide: A Highly Reactive Silylating Agent for Primary and Secondary Alcohols
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Trimethylsilylazide reacts very rapidly with primary and secondary alcohols at room temperature to give high yields of trimethylsilyl ethers.
- Sinou, D.,Emziane, M.
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- Introduction of a New Ionic Liquid Catalyst for the Trimethylsilyl and Tetrahydropyranyl Protection of Alcohols
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1,1'-Disulfo-[2,2'-bipyridine]-1,1'-hydrogen sulfate, BiPy(SO3H)2(HSO4)2, is prepared and identified as a new ionic liquid. This reagent was used for the promotion of the chemoselective trimethylsilyl and tetrahydropyranyl protection of alcohols. All reactions were performed under mild reaction conditions in high to excellent yields. Ease of the preparation of the heterogeneous catalyst, simplicity and easy work-up procedure, high reaction rates, and recyclability and reusability of the catalyst are the main advantages of this method.
- Shirini, Farhad,Abedini, Masoumeh,Mahmoodi, Nosratollah,Biglari, Mohammad,Safarpoor Nikoo Langrudi, Mohaddeseh
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- Al(HSO4)3 as an efficient reagent for the selective trimethylsilylation of primary alcohols under solvent-free conditions
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Primary alcohols are selectively trimethylsilylated using Hexamethyldisilazane (HMDS) in the presence of a catalytic amount of Al(HSO 4)3 under solvent free conditions. Copyright Taylor & Francis Inc.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh
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- A novel and highly efficient method for the direct conversion of aryl aldehyde bisulfite adducts to their aryl trimethylsilyl ethers in a one-pot manner catalyzed by montmorillonite K-10
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A new, convenient, and chemoselective method has been developed for the one-pot conversion of aryl aldehyde bisulfite adducts to the corresponding trimethylsilyl ethers. Copyright Taylor & Francis LLC.
- Khodaei, Mohammad M.,Khosropour, Ahmad R.,Abbasi, Jamshide
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- Indium tribromide: An efficient catalyst for the silylation of hydroxy groups by the activation of hexamethyldisilazane
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A variety of substrates containing hydroxy groups have been protected as their corresponding trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyldisilazane in the presence of indium tribromide. The catalyst indium tribromide activates the 1,1,1,3,3,3-hexamethyldisilazane and accelerates the reaction under mild reaction conditions at room temperature. Georg Thieme Verlag Stuttgart.
- Yadav,Reddy,Basak,Baishya,Venkat Narsaiah
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- Zinc mediated reactions in organic synthesis: Efficient synthesis of silyl ethers under mild conditions
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General and practical method for the syn the sis of silyl ethers in the presence of zinc powder under mild conditions has been described.
- Bandgar, Babasaheb Pandurang,Chavare, Satish Navnath,Pandit, Shivaji Sandu
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- Poly(N-bromobenzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as novel catalytic reagents for silylation of alcohols, phenols, and thiols using hexamethyldisilazane
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Poly(N-bromobenzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] are effective catalysts for the silylation of alcohols, phenols, and thiols in the presence of hexamethyldisilazane with, or without solvent, and also under microwave irradiation.
- Ghorbani-Vaghei, Ramin,Zolfigol, Mohammad Ali,Chegeny, Mahdieh,Veisi, Hojat
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- Natural kaolinitic clay : A mild and efficient catalyst for the tetrahydropyranylation and trimethylsilylation of alcohols
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Natural kaolinitic clay possessing transition metals such as Fe, Ti in its lattice has been found to catalyze efficiently the protection of a variety of alcohols with 2,3-dihydro-4H-pyran (DHP) and hexamethyldisilazane (HMDS) at ambient conditions.
- Upadhya,Daniel,Sudalai,Ravindranathan,Sabu
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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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- 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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- 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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- Iron-Catalyzed Grignard Cross-Couplings with Allylic Methyl Ethers or Allylic Trimethylsilyl Ethers
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We have found that cross-coupling between aryl Grignard reagents and allylic methyl ethers proceeded well in the presence of a catalytic amounts of Fe(acac) 3 to afford the corresponding allylic substitution products in good yields. Under the same conditions, allylic trimethylsilyl ethers also reacted with Grignard reagents to give the corresponding cross-coupling products.
- Seto, Chika,Otsuka, Takeshi,Takeuchi, Yoshiki,Tabuchi, Daichi,Nagano, Takashi
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supporting information
p. 1211 - 1214
(2018/03/26)
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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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- Magnetic nanoparticle-supported DABCO tribromide: A versatile nanocatalyst for the synthesis of quinazolinones and benzimidazoles and protection/deprotection of hydroxyl groups
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1,4-Diazabicyclo[2.2.2]octane tribromide supported on magnetic Fe3O4 nanoparticles (MNPs-DABCO tribromide) as a novel heterogeneous tribromide type compound was found to be an efficient and reusable nanocatalyst for the one-pot synthesis of 2-arylquinazolin-4(3H)-ones and 2-aryl-1H-benzo[d]imidazoles through oxidative cyclization of aldehydes with 2-aminobenzamides and 1,2-phenylenediamine, respectively. Also, MNPs-DABCO tribromide catalyzed trimethylsilylation/tetrahydropyranylation and desilylation/depyranylation of a wide variety of alcohols and phenols through changing the solvent medium at room temperature.
- Rostami, Amin,Pourshiani, Omid,Navasi, Yahya,Darvishi, Neda,Saadati, Shaghayegh
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p. 9033 - 9040
(2017/08/29)
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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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- Stereoselective synthesis of allyl ethers using α,β-unsaturated acylsilanes
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The reaction behavior of silylvinylmethanols with acid catalysts was investigated. The starting silylvinylmethanols 2 were prepared by the reaction of the corresponding α,β-unsaturated acylsilanes 1 with organocerium reagents. The reaction of 2 with TsOH
- Honda, Mitsunori,Takatera, Takehide,Ui, Ryosuke,Kunimoto, Ko-Ki,Segi, Masahito
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p. 864 - 869
(2017/02/18)
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- Practical Photocatalytic Trifluoromethylation and Hydrotrifluoromethylation of Styrenes in Batch and Flow
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Styrenes represent a challenging class of substrates for current radical trifluoromethylation and hydrotrifluoromethylation methods due to a myriad of potential side reactions. Herein, we describe the development of mild, selective and broadly applicable photocatalytic trifluoromethylation and hydrotrifluoromethylation protocols for these challenging substrates. The methods use fac-Ir(ppy)3, visible light and inexpensive CF3I and can be applied to a diverse set of vinylarene substrates. The use of continuous-flow photochemical reaction conditions allowed to reduce the reaction time and increase the reaction selectivity.
- Straathof, Natan J. W.,Cramer, Sten E.,Hessel, Volker,No?l, Timothy
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supporting information
p. 15549 - 15553
(2016/12/09)
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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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- Rice husk: Introduction of a green, cheap and reusable catalyst for the protection of alcohols, phenols, amines and thiols
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A mild, efficient and eco-friendly protocol for the chemoselective protection of benzylic and primary and less hindered secondary aliphatic alcohols and phenols as trimethylsilyl ethers and different types of amines as N-tert-butylcarbamates is developed using rice husk (RiH) as the catalyst. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols and amines with acetic anhydride. Easy work-up, relatively short reaction times, excellent yields and low cost, availability and reusability of the catalyst are the striking features of this methodology, which can be considered to be one of the best and general methods for the protection of alcohols, phenols, thiols and amines. In addition, the use of a green reagent in the above-mentioned reactions results in a reduction of environmental pollution and of the cost of the applied methods.
- Shirini, Farhad,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali,Aliakbar, Ali-Reza
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p. 164 - 170
(2014/03/21)
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- Rice husk ash: A new, cheap, efficient, and reusable reagent for the protection of alcohols, phenols, amines, and thiols
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Amild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields. Copyright
- Shirini,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali
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p. 577 - 586
(2014/06/09)
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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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- Highly atom economical uncatalysed and I2-catalysed silylation of phenols, alcohols and carbohydrates, using HMDS under solvent-free reaction conditions (SFRC)
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An uncatalysed silylation of phenols, regardless on the aggregate state and nature of the substituents with 0.55 equiv of HMDS under solvent-free reaction conditions (SFRC) at room temperature is reported. Sterically hindered phenols, carbohydrates and most of the alcohols additionally required a catalytic amount (up to 2 mol %) of iodine. The reaction protocol is very simple; obtaining a pure product, particularly of uncatalysed reactions, was frequently a completely solvent-free process.
- Jereb, Marjan
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experimental part
p. 3861 - 3867
(2012/06/30)
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- Gold nanoparticles-catalyzed activation of 1,2-disilanes: Hydrolysis, silyl protection of alcohols and reduction of tert-benzylic alcohols
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Gold nanoparticles supported on TiO2 catalyze under mild conditions the activation of a series of 1,2-disilanes towards hydrolysis and alcoholysis, with concomitant evolution of H2 gas. For the case of tert-benzyl alcohols, the main or only pathway is reduction to the corresponding alkanes.
- Gryparis, Charis,Stratakis, Manolis
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supporting information
p. 10751 - 10753,3
(2020/09/02)
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- An alternative to nitromethane as solvent: The promoting influence of nitro-functionalized imidazolium salts for synthesis and catalysis
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Nitromethane, a volatile and toxic organic compound, is commonly used as solvent for organic and catalytic reactions. In order to find an alternative for this specific nitro-containing organic solvent, the performance of some nitro-functionalized imidazolium salts such as 1-methyl-3-(4-nitrobenzyl) imidazolium hexafluorophosphate, 1-methyl-3-(4-nitrobenzyl)imidazolium tetrafluoroborate, 1-methyl-3-(4-nitrobenzyl)imidazolium bis(trifluoromethanesulfonyl)amide and 1,2-dimethyl-3-(4- nitrobenzyl) imidazolium hexafluorophosphate, was examined in some reactions including trimethylsilylation of alcohols with hexamethyldisilazane, ring-opening reactions of 2-aryl-3,4-dihydropyrans with thiophenols or thiols, and a copper- mediated oxidative coupling of alkynes. As expected, these imidazolium salts can indeed replace nitromethane in these reactions. Particularly, the imidazolium salt along with the metal catalyst, if involved, can be easily recovered and reused without significant loss of activity. The use of these nitro-functionalized imidazolium salts as alternative solvents for nitromethane not only confers a green aspect to the reaction system, but also facilitates a rational design of a catalytic system with the concept of green chemistry. Copyright
- Ren, Yajun,Li, Minghao,Yang, Jie,Peng, Jiajian,Gu, Yanlong
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experimental part
p. 3473 - 3484
(2012/02/04)
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- Nickel-catalyzed allylic substitution of simple alkenes
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This report describes a nickel-catalyzed allylic substitution process of simple alkenes whereby an important structural motif, a 1,4-diene, was prepared. The key to success is the use of an appropriate nickel-phosphine complex and a stoichiometric amount of silyl triflate. Reactions of 1-alkyl-substituted alkenes consistently provided 1,1-disubstituted alkenes with high selectivity. Insight into the reaction mechanism as well as miscellaneous application of the developed catalytic process is also documented.
- Matsubara, Ryosuke,Jamison, Timothy F.
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supporting information; experimental part
p. 1860 - 1875
(2012/02/02)
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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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- 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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- Rapid and efficient protection of alcohols and phenols, and deprotection of trimethylsilyl ethers catalyzed by a cerium-containing polyoxometalate
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Herein, we want to report a simple and convenient way for protection-deprotection of alcohols in the presence of ammonium decatungstocerate(IV) {(NH4)8[CeW10O 36]A·20H2O} as catalyst under ambient temperature in CH3CN. Using 0.002 mmol of the catalyst, various alcohols and phenols were transformed easily to the corresponding TMS ethers in excellent yields. In the second part, various TMS ethers were successfully converted to the parent hydroxyl compounds in the presence of the ammonium decatungstocerate(IV) catalyst.
- Yadollahi, Bahram,Mirkhani, Valiollah,Tangestaninejad, Shahram,Karimian, Davud
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experimental part
p. 83 - 86
(2012/06/18)
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- Nickel-catalyzed allylic substitution of simple alkenes
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Nickel-catalyzed intermolecular allylic substitution of simple alkenes (ethylene and alpha olefins) is described. This method is the first catalytic intermolecular process for direct allylation of nonconjugated, nonstrained simple alkenes. Catalyst loadings as low as 2.5 mol % Ni afford the desired product in high yield in both gram-scale and smaller scale coupling reactions.
- Matsubara, Ryosuke,Jamison, Timothy F.
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supporting information; experimental part
p. 6880 - 6881
(2010/07/05)
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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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- 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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- Nafion SAC-13: heterogeneous and reusable catalyst for the activation of HMDS for efficient and selective O-silylation reactions under solvent-free condition
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Nafion SAC-13 effectively activates hexamethyldisilazane (HMDS) for the efficient and selective silylation of alcohols. Primary, secondary, and tertiary alcohols and phenols are efficiently converted to their corresponding silylethers in short reaction ti
- Rajagopal, Gurusamy,Lee, Hanbin,Kim, Sung Soo
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experimental part
p. 4735 - 4741
(2009/10/09)
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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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- Silica sulfuric acid as a reusable catalyst for efficient and simple silylation of hydroxyl groups using hexamethyldisilazane (HMDS)
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At room temperature, alcohols and phenols are efficiently protected with hexamethyldisilazane (HMDS) in the presence of silica sulfuric acid in good to excellent yields. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. Copyright Taylor and Francis Group, LLC.
- Ghafuri, Hossein,Eftekhari-Sis, Bagher,Hashemi, Mohammed M.
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p. 1645 - 1651
(2008/02/08)
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- Mechanistic analysis of the photocycloaddition of silyl-tethered alkenes
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(Chemical Equation Presented) The photochemistry of substituted cinnamyloxy silanes has been examined in both cyclohexane and acetonitrile solvents. Alkene isomerization occurs in addition to cycloaddition. Fluorescence quantum yields and excited singlet state lifetimes have been determined for each compound. We have used the information in order to better understand the regio- and stereoselectivity of photocycloaddition between silyl-tethered cinnamyl groups. This study allows us to conclude that the 2 + 2 photocycloaddition between alkenes is not a Woodward-Hoffmann orbital symmetry controlled event. The most consistent explanation for the excellent regio- and stereoselectivity is that the photocycloaddition is conformationally controlled.
- Fleming, Steven A.,Parent, Alexander A.,Parent, Ephraim E.,Pincock, James A.,Renault, Lise
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p. 9464 - 9470
(2008/03/14)
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- Efficient and stereoselective synthesis of allylic ethers and alcohols
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(Chemical Equation Presented) A short and efficient synthesis of allylic TBS ethers and allylic alcohols has been developed, based upon a unique Kocienski-Julia olefination reaction. Allylic alcohols and allylic ethers are obtained in good to excellent yields and with high (E)-selectivity. The conditions are mild and the procedure is broadly applicable.
- Pospisil, Jiri,Marko, Istvan E.
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p. 5983 - 5986
(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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- Efficient trimethylsilylation and tetrahydropyranylation of alcohols in the presence of 1,3-dibromo-5,5-dimethylhydantoin
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Chemoselective trimethylsilylation and tetrahydropyranylation of benzylic and primary and secondary aliphatic alcohols proceed efficiently in the presence of 1,3-dibromo-5,5-dimethylhydantoin (DBH) under mild and completely heterogeneous reaction conditio
- Shirini, Farhad,Zolfigol, Mohammad Ali,Paktinat, Maryam
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p. 4252 - 4256
(2008/03/27)
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- Silylation and tetrahydropyranylation of alcohols catalyzed by Al(HSO 4)3
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Trimethylsilylation and tetrahydropyranylation of alcohols are efficiently catalyzed by Al(HSO4)3. All reactions were performed under mild and completely heterogeneous conditions in good-to-high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh
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p. 1982 - 1985
(2007/10/03)
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- Sulfuric acid supported on silica gel: An efficient catalyst for silylation of hydroxyl groups with HMDS and their convenient deprotection under non-aqueous condition
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A mild and efficient silylation of alcohols and phenols with hexamethyl-disilazane(HMDS) and convenient desilylation of the corresponding silyl ethers are achieved using a catalytic amount of H2SO4 SiO2 under non-aqueous condition. In this work chemoselective silylation of hydroxy compounds in the presence of thiols and amines is conducted.
- Lakouraj,Akbari
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p. 1165 - 1167
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- Silylation of hydroxy groups with HMDS under microwave irradiation and solvent-free conditions
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Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields.
- Mojtahedi,Saidi,Bolourtchian,Heravi
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p. 289 - 292
(2007/10/03)
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- Efficient o-trimethylsilylation of alcohols and phenols with trimethylsilyl azide catalyzed by tetrabutylammonium bromide under neat conditions
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A very efficient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols is reported. The reactions were carried out under neat conditions with trimethylsilyl azide (TMSN3) and, when necessary, in the presence of a catalytic amount (20 mol %) of tetrabutylammonium bromide (TBABr) at 30 or 70 °C. Under catalytic conditions, the yields of the corresponding trimethylsilyl ethers were greater than 91%. This procedure also allows the selective protection of primary and secondary alcohols in the presence of tertiary ones.
- Amantini,Fringuelli,Pizzo,Vaccaro
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p. 6734 - 6737
(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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- Fast, convenient, and efficient molybdenum-catalyzed asymmetric allylic alkylation under noninert conditions: An example of microwave-promoted fast chemistry
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Microwave heating allows regio- and enantioselective allylic alkylation to be carried out in air in a few minutes in a convenient one-pot procedure [Eq. (1)]. The catalytically active molybdenum(0) species was formed in situ from inexpensive [Mo(CO)6] and a chiral ligand.
- Kaiser, Nils Fredrik K.,Bremberg, Ulf,Larhed, Mats,Moberg, Christina,Hallberg, Anders
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p. 3595 - 3598
(2007/10/03)
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- Facile O-silylation of tertiary alcohols in the presence of Mg-metal
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Treatment of aliphatic alcohols with trimethylsilyl chloride (TMSCl) in N,N-dimethylformamide (DMF) containing Mg-turning at room temperature brought about facile and efficient O-silylation to give the corresponding trimethylsilyl ethers in good to excellent yields. This method can be also available for sterically hindered tert-alcohols and alcohols having a variety of substituents which may be labile under the basic conditions used in the conventional O-silylation.
- Nishiguchi, Ikuzo,Kita, Yoshio,Watanabe, Masamitsu,Ishino, Yoshio,Ohno, Toshinobu,Maekawa, Hirofumi
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p. 1025 - 1027
(2007/10/03)
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