- Comparison of the efficiency of two dicationic ionic liquids catalysts based on perchloric acid for the protection of alcohols
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In this article, two aliphatic and aromatic types of dicationic acidic ionic liquids formulated as [H2-DABCO][ClO4], [H2-Bisim][ClO4]2 were used for the acceleration of the protection of alcohols as t
- Rahmanzadeh, Akram,Daneshvar, Nader,Shirini, Farhad,Tajik, Hassan
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Read Online
- Allylation of imines with allyltrimethylsilane and experimental evidences for a fluoride-triggered autocatalysis mechanism of the Sakurai- Hosomi reaction
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This article reports the reaction of allyltrimethylsilane 1 with aldimines 2 in the presence of tetra-n-butylammonium fluoride to give the corresponding homoallylamines 3 in moderate to excellent yields. The allylation mechanism of imines as well as that of aldehydes can be reasonably interpreted by a fluoride-triggered autocatalytic procedure.
- Wang, De-Kun,Zhou, Yong-Gui,Tang, Yong,Hou, Xue-Long,Dai, Li-Xin
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Read Online
- An asymmetric Salamo-based Zn complex supported on Fe3O4MNPs: a novel heterogeneous nanocatalyst for the silyl protection and deprotection of alcohols under mild conditions
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In this study, a magnetic asymmetric Salamo-based Zn complex (H2L = salen type di-Schiff bases)-supported on the surface of modified Fe3O4(Fe3O4@H2L-Zn) as a new catalyst was designed and characterizedvianumerous analytical techniques such as FT-IR spectroscopy, XRD, EDS, ICP-AES, SEM, TEM, TGA and VSM. An efficient and sustainable synthetic protocol has been presented for the synthesis of silyl ether substructuresviathe silyl protection of alcohols under mild conditions. The synthetic protocol involves a two-component solvent-free reaction between various hydroxyl-bearing substrates and hexamethyldisilazane (HMDS) as an inexpensive silylating agent using Fe3O4@H2L-Zn MNPs as a magnetically separable, recyclable and reusable heterogeneous catalyst. Fe3O4@H2L-Zn MNPs were also applied for the removal of silyl protecting groups from hydroxyl functions using water in CH2Cl2under green conditions. The catalyst demonstrated good to excellent catalytic yield efficiency for both the reactions compared to the commercial metal-based catalysts under green conditions for a wide range of substrates.
- Yao, Hongyan,Wang, Yongsheng,Razi, Maryam Kargar
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p. 12614 - 12625
(2021/04/14)
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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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- Use of Silylated Formiates as Hydrosilane Equivalents
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The present invention relates to a method for preparing organic compounds of formula (I) by reaction between a silylated formiate of formula (II) and an organic compound in the presence of a catalyst and optionally of an additive. The invention also relates to use of the method for preparing organic compounds of formula (I) for the preparation of reagents for fine chemistry and for heavy chemistry, as well as in the production of vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, and pesticides.
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Paragraph 0502-0505
(2021/09/26)
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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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- Synthesis and characterization of a bifunctional nanomagnetic solid acid catalyst (Fe3O4@CeO2/SO42?) and investigation of its efficiency in the protection process of alcohols and phenols via hexamethyldisilazane under solvent-free conditions
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In this research, Fe3O4@CeO2 (FC) was synthesized using the coprecipitation method and functionalized by an ammonium sulfate solution to achieve a heterogeneous solid acid Fe3O4@CeO2/SO42? (FCA) catalyst. The synthesized bifunctional catalyst was used in the protection process of alcohols and phenols using hexamethyldisilazane (HMDS) at ambient temperature under solvent-free conditions. Due to its excellent magnetic properties, FCA can easily be separated from the reaction mixture and reused several times without significant loss in its catalytic activity. Excellent yield and selectivity, simple separation, low cost, and high recyclability of the nanocatalyst are outstanding advantages of this procedure. The characterization was carried out using different techniques such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM).
- Mohammadiyan, Esmaeel,Ghafuri, Hossein,Kakanejadifard, Ali
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p. 171 - 178
(2018/09/12)
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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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- C?C Bond Formation of Benzyl Alcohols and Alkynes Using a Catalytic Amount of KOtBu: Unusual Regioselectivity through a Radical Mechanism
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We report a C?C bond-forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α-alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways.
- Kumar, Amit,Janes, Trevor,Chakraborty, Subrata,Daw, Prosenjit,von Wolff, Niklas,Carmieli, Raanan,Diskin-Posner, Yael,Milstein, David
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supporting information
p. 3373 - 3377
(2019/02/14)
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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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- 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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- 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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- 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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- 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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- 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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- Silanol Compound, Composition, and Method for Producing Silanol Compound
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The purpose of the present invention is to provide silanol compounds that can be used as raw materials of siloxane compounds and the like, and a composition of the silanol compounds, as well as to provide a production method that makes it possible to produce silanol compounds at excellent yield. A composition comprising 5 mass % to 100 mass % of a silanol compound represented by Formulas (A) to (C) can be prepared by devising to produce silanol compounds under water-free conditions, to produce silanol compounds in a solvent having the effect of suppressing the condensation of silanol compounds, and to perform other such processes, the composition being able to be used as a raw material or the like of siloxane compounds because the silanol compounds can be stably present in the resulting composition.
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Paragraph 0162
(2017/07/14)
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- Iron-Catalyzed Silylation of Alcohols by Transfer Hydrosilylation with Silyl Formates
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An iron catalyst is shown for the first time to promote transfer hydrosilylation with silyl formates and is utilized for the silylation of alcohols. Attractive features of this protocol include the use of an earth-abundant transition-metal catalyst, mild reaction conditions, and the release of gases as the only byproducts (H 2 and CO 2).
- Godou, Timothé,Chauvier, Clément,Thuéry, Pierre,Cantat, Thibault
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supporting information
p. 2473 - 2477
(2017/10/26)
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- Silylation of O-H bonds by catalytic dehydrogenative and decarboxylative coupling of alcohols with silyl formates
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The silylation of O-H bonds is a useful methodology in organic synthesis and materials science. While this transformation is commonly achieved by reacting alcohols with reactive chlorosilanes or hydrosilanes, we show herein for the first time that silylformates HCO2SiR3 are efficient silylating agents for alcohols, in the presence of a ruthenium molecular catalyst.
- Chauvier, Clément,Godou, Timothé,Cantat, Thibault
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supporting information
p. 11697 - 11700
(2017/11/03)
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- Oxidative [1,2]-Brook Rearrangements Exploiting Single-Electron Transfer: Photoredox-Catalyzed Alkylations and Arylations
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Oxidative [1,2]-Brook rearrangements via hypervalent silicon intermediates induced by photoredox-catalyzed single-electron transfer have been achieved, permitting the formation of reactive radical species that can engage in alkylations and arylations.
- Deng, Yifan,Liu, Qi,Smith, Amos B.
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p. 9487 - 9490
(2017/07/24)
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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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- 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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- 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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- 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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p. 1912 - 1921
(2015/12/12)
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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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- RuIII(OTf)SalophenCH2-NHSiO2-Fe: An efficient and magnetically recoverable catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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Efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by ruthenium(III) complex of chloromethylated Salophen supported on nanomagnetic materials is reported. First, the iron nanomagnets were silica coated, functi
- Torki, Maryam,Tangestaninejad, Shahram,Mirkhani, Valiollah,Moghadam, Majid,Mohammadpoor-Baltork, Iraj
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p. 304 - 309
(2014/04/03)
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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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- Novel protocol for the synthesis of organic ammonium tribromides and investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium bis(tribromide) in the silylation of alcohols and thiols
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A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br-to Br3-. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.
- Dey, Rupa R.,Paul, Bappi,Dhar, Siddhartha S.,Bhattacharjee, Sushmita
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supporting information
p. 1545 - 1547
(2015/02/19)
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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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- Synthesis and characterization of 2-carboxyethyltriphenyl phosphonium tribromide and its application as catalyst in silylation of alcohols and thiols under solvent-free condition
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A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been synthesized by reacting triphenyl phosphine with acrylic acid and potassium bromide under solvent-free condition followed by oxidation of Br- to with KMnO4. This hitherto unknown tribromide reagent is characterized by ultraviolet-visible, Fourier transform-infrared, 1H NMR, and 31P NMR spectroscopy. Its efficacy as catalyst is established by investigating its catalytic activity in silylation of alcohols and thiols by hexamethyl disilazane (HMDS). It is found to be a very good catalyst and selectively and efficiently catalyzes the silylation reactions. Copyright
- Dey, Rupa Rani,Dhar, Siddhartha Sankar
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supporting information
p. 2355 - 2363
(2014/07/22)
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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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- Carboxylation with CO2 via brook rearrangement: Preparation of α-hydroxy acid derivatives
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In the presence of CsF, a wide range of α-substituted α-siloxy silanes were carboxylated under a CO2 atmosphere (1 atm) via Brook rearrangement. A variety of α-substituents including aryl, alkenyl, and alkyl groups were tolerated to afford α-hydroxy acids in moderate-to-high yields. One-pot synthesis from aldehydes using PhMe2SiLi and CO 2 was also possible, providing α-hydroxy acids without the isolation of an α-hydroxy silane.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
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supporting information
p. 14 - 17
(2014/01/23)
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- Salt-free preparation of trimethylsilyl ethers by B(C6F 5)3-catalyzed transfer silylation by using a Me 3SiH surrogate
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An unprecedented transfer silylation of alcohols catalyzed by the strong Lewis acid B(C6F5)3 is described. Gaseous Me3SiH is released in situ by B(C6F5) 3-catalyzed decomposition of 3-trimethylsilylcyclohexa-1,4-diene and subsequently reacts with an alcohol in a dehydrogenative Si-O coupling promoted by the same boron catalyst. Benzene and dihydrogen are formed during the reaction, but no salt waste is. This expedient protocol is applicable to several silicon groups, and the preparation of trimethylsilyl ethers presented here is potentially useful for alcohol derivatization prior to GLC analysis. Copyright
- Simonneau, Antoine,Friebel, Jonas,Oestreich, Martin
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supporting information
p. 2077 - 2083
(2014/04/17)
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- Fe(TAML)Li/(diacetoxyiodo)benzene-mediated oxidation of alcohols: Evidence for mild and selective C-O and C-C oxidative cleavage in lignin model transformations
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A novel combination of Fe(TAML)Li and (diacetoxyiodo)- benzene for the oxidation of primary and secondary alcohols at 25 °C in acetone is reported. In view of the interesting ability of this system to selectively cleave specific types of C-C bonds of elaborated alcohols, the application of this novel combination to the oxidative cleavage of lignin model molecules was investigated. Considering the numerous supported versions of the oxidant as well as the mild conditions employed, the developed methodology appears to be a promising lignin depolymerization strategy.
- Napoly, Francois,Jean-Gerard, Ludivine,Goux-Henry, Catherine,Draye, Micheline,Andrioletti, Bruno
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supporting information
p. 781 - 787
(2014/03/21)
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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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- {[[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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- 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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- Efficient room-temperature O-silylation of alcohols using a SBA-15-supported cobalt(II) nanocatalyst
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The O-silylation of OH groups of alcohols and phenols with hexamethyldisilazane (HMDS) was achieved in high-to-excellent yields using catalytic quantities of a SBA-15-supported cobalt(II) nanocatalyst (typically 0.5 mol-%) at room temperature and under solvent-free conditions. Furthermore, the heterogeneous catalyst showed an excellent durability and can be conveniently reused by filtration for at least twelve times without any noticeable loss of activity. Copyright
- Rajabi, Fatemeh,Luque, Rafael,Serrano-Ruiz, Juan Carlos
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p. 1823 - 1828
(2012/10/29)
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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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- 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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- 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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- Cu(NO3)2 · 3 H2O as an efficient reagent for the chemoselective trimethylsilylation of primary alcohols and oxidation of trimethylsilyl ethers
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Cu(NO3)2 · 3 H2O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO2 and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.
- Shirini,Mashhadi-Nejad
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experimental part
p. 376 - 381
(2012/04/04)
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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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- 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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- Highly efficient and chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable electron-deficient [TiIV(salophen)(OTf)2]
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In the present work, highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by high-valent [Ti IV(salophen)(OTf)2] is reported. Under these conditions, primary, secondary and tertiary alcohols as well as phenols were silylated in short reaction times and high yields. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.
- Yadegari, Maryam,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 332 - 338
(2012/03/12)
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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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- Process development and optimization for production of a potassium ion channel blocker, ICA-17043
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A scalable process for the manufacture of a potassium ion channel blocker was developed and optimized. Key features of the process include an optimized Grignard reaction, a direct cyanation of the intermediate trityl alcohol derivative, and an improved nitrile hydrolysis protocol, relative to the original acidic hydrolysis conditions, to generate the crude active pharmaceutical ingredient (API) with >95% HPLC purity. The Grignard and the cyanation reactions could be telescoped, resulting in an improved throughput compared to the original four-step process. An effective recrystallization of the API was also developed and the process scaled up to manufacture multiple batches at the pilot scale.
- Mobele, Bingidimi I.,Venkatraman, Sripathy,McNaughton-Smith, Grant,Gibb, Cameron,Ulysse, Luckner G.,Lindmark, Carl A.,Shaw, Stephen,Marron, Brian,Spear, Kerry,Suto, Mark J.
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p. 1385 - 1392
(2012/11/07)
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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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- 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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- 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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