- 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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- Co2(CO)8-catalyzed reactions of acetals or lactones with hydrosilanes and carbon monoxide. A new access to the preparation of 1,2-diol derivatives through siloxymethylation
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The Co2(CO)8-catalyzed reaction of acetals with hydrosilanes and CO under mild reaction conditions (an ambient temperature under an ambient CO pressure), leading to the production of vicinal diols is reported. A siloxymethyl group can be introduced via the cleavage of one of two alkoxy groups in the acetal. The effects of the types of hydrosilanes, acetals, solvents, and reaction temperatures on the yield of siloxymethylation products were examined in detail. The reactivity for hydrosilanes is as follows; HSiMe3 > HSiEtMe2 > HSiEt2Me > HSiEt3. Hemiacetal esters are more reactive than dimethyl acetals. The polarity of the solvent used also has a significant effect on both the course of the reaction as well as the reaction rate. The site-selective siloxymethylation can be achieved in the case of cyclic acetals such as tetrahydrofuran (THF) and tetrahydropyrane (THP) derivatives, depending on the nature of the oxygen substituent attached adjacent to the oxygen atom in the ring. When 2-alkoxy THF or THP derivatives are used as substrates, the siloxymethylation takes place with cleavage of the ring C-O bond. In contrast, the reaction of 2-acetoxy THF or THP derivatives results in siloxymethylation with the cleavage of C-OAc bond. The ring-opening siloxymethylation of lactones was also examined.
- Chatani, Naoto,Fujii, Satoru,Kido, Yoichi,Nakayama, Yasuhide,Kajikawa, Yasuteru,Tokuhisa, Hideo,Fukumoto, Yoshiya,Murai, Shinji
-
-
- Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
-
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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- 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
-
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)
-
- 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)
-
- 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
-
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
-
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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- Nanomagnetic zirconia-based sulfonic acid (Fe3O4@ZrO2-Pr-SO3H): A new, efficient and recyclable solid acid catalyst for the protection of alcohols: Via HMDS under solvent free conditions
-
In the present work, sulfonic acid functionalized nanomagnetic zirconia is prepared by the reaction of (3-mercaptopropyl)trimethoxysilane and nanomagnetic zirconia. Then, nanomagnetic zirconia-based sulfonic acid (Fe3O4@ZrO2/su
- Tadjarodi, Azadeh,Khodikar, Rahim,Ghafuri, Hosssein
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p. 63480 - 63487
(2016/07/19)
-
- First example of borirane synthesis by α-olefins reaction with BCl3·SMe2 Catalyzed with (η5-C5H5)2TiCl2
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New method was developed of the synthesis of 2-phenyl(alkyl, benzyl, phenoxy)-1-chloroboriranes via reaction of α-olefins with BCl3·SMe2 catalyzed by Cp2TiCl2. The method is based on the boracyclopropanes (boriranes) formation resulting from transmetallation of titanacyclopropanes arising from the reaction of α-olefins with Cp2TiCl2. The calculations were fulfilled of thermodynamic and activation parameters of possible reaction routes.
- Khusainova,Khafizova,Tyumkina,Dzhemilev
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p. 1517 - 1523
(2015/12/30)
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- 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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- Highly efficient protection of alcohols and phenols catalysed by tin porphyrin supported on MIL-101
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The catalytic activity of 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], supported on chloromethylated MIL-101, was investigated in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and also their tetrahydropyranylation with 3,4-dihydro-2H-pyran. Excellent yields, mild reaction conditions, short reaction times and reusability of the catalyst without significant decrease in its initial activity are noteworthy advantages of this supported catalyst.
- Zadehahmadi, Farnaz,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Kardanpour, Reihaneh
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p. 209 - 215
(2015/03/30)
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- Selective silylation of alcohols, phenols and oximes using N-chlorosaccharin as an efficient catalyst under mild and solvent-free conditions
-
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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- 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
-
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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- 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
-
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
-
supporting information
p. 781 - 787
(2014/03/21)
-
- {[[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)
-
- Efficient room-temperature O-silylation of alcohols using a SBA-15-supported cobalt(II) nanocatalyst
-
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
-
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
-
-
- P2O5/SiO2 as an efficient and mild catalyst for trimethylsilylation of alcohols using hexamethyldisilazane
-
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)
-
- Cu(NO3)2 · 3 H2O as an efficient reagent for the chemoselective trimethylsilylation of primary alcohols and oxidation of trimethylsilyl ethers
-
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
-
experimental part
p. 376 - 381
(2012/04/04)
-
- Protection of hydroxyl groups as a trimethylsilyl ether by 1,1,1,3,3,3-hexamethyldisilazane promoted by aspartic acid as an efficient organocatalyst
-
A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic, metal-free, and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions. The procedure is operationally simple and the silylated product was obtained in high yield and purity.
- Ghorbani-Choghamarani, Arash,Norouzi, Masoomeh
-
scheme or table
p. 595 - 598
(2012/01/06)
-
- [H2-Cryptand 222]2+(Br3-) 2 as a tribromide-type catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols
-
A stable organic tribromide, [H2-cryptand 222] 2+(Br3-)2 was utilized as an active catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols.
- Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Khakyzadeh, Vahid,Gholami, Hadi,Niknam, Khodabakhsh
-
experimental part
p. 127 - 131
(2012/06/18)
-
- Trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel
-
An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, e
- Shaterian, Hamid Reza,Fahimi, Nafiseh,Azizi, Kobra
-
experimental part
p. 1604 - 1611
(2011/10/05)
-
- Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
-
New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, 1H NMR and 13C NMR studies. All the products were extensively characterized by 1H NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Khaligh, Nader Ghaffari
-
experimental part
p. 63 - 70
(2011/12/02)
-
- Succinimide-N-sulfonic acid: A mild, efficient, and reusable catalyst for the chemoselective trimethylsilylation of alcohols and phenols
-
Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields. Copyright Taylor & Francis Group, LLC.
- Shirini,Khaligh, Nader Ghaffari
-
experimental part
p. 2156 - 2165
(2012/04/10)
-
- Rapid and efficient trimethylsilyl protection of hydroxyl groups catalyzed by niobium(V) chloride
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An efficient and convenient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, and phenols with hexamethyldisilazane, has been developed. The reactions were carried out at room temperature in the presence of a catalytic amount of niobium(V) chloride and afforded the corresponding trimethylsilyl ethers in high to excellent yields in short time. Copyright Taylor & Francis Group, LLC.
- Hou, Jun-Tao,Chen, Hong-Li,Zhang, Zhan-Hui
-
experimental part
p. 88 - 93
(2011/04/22)
-
- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalysed by in situ generated I2 using Oxone /KI or cerium ammonium nitrate (CAN)/KI systems under mild conditions
-
Structurally diverse alcohols and phenols were trimethylsilylated in clean and efficient reactions with hexamethyldisilazane (HMDS) in the presence of a catalytic amount of I2 generated in situ from Oxone /KI or CAN/KI systems. The reactions occur rapidly in good to high yields in wet CH2Cl2 at room temperature. Indian Academy of Sciences.
- Kolvari, Eskandar,Khazaei, Ardeshir,Zolfigol, Mohammad Ali,Koukabi, Nadiya,Gilandoust, Maryam,Bakhit, Neda
-
experimental part
p. 703 - 708
(2012/07/14)
-
- Cross-linked poly(4-vinylpyridine/styrene) copolymer-supported bismuth(III) triflate: An efficient heterogeneous catalyst for silylation of alcohols and phenols with HMDS
-
Cross-linked poly(4-vinylpyridine/styrene) copolymer-supported bismuth(III) triflate (30P/S-Bi) effectively activates hexamethyldisilazane (HMDS) for the silylation of alcohols and phenols. By the use of this heterogeneous catalytic system, a wide range of alcohols as well as phenols are converted into their corresponding trimethylsilyl ethers in high yield under mild reaction conditions. The catalyst was reused more than 10 times without significant loss of its catalytic activity.
- Lee, Sang-Hyeup,Kadam, Santosh T.
-
experimental part
p. 608 - 615
(2011/11/12)
-
- Polyvinylpolypyrrolidoniume tribromide as new and metal-free catalyst for the formylation and trimethylsilylation of hydroxyl group
-
Trimethylsilylation of alcohols was achieved using 1,1,1,3,3,3- hexamethyldisilazane (HMDS) as silylating agent, in the presence of polyvinylpolypyrrolidoniume tribromide in acetonitrile at room temperature. Also a variety of alcohols were converted into alkyl formates by ethyl formate and a catalytic amount of polyvinylpolypyrrolidoniume tribromide under solvent free conditions at room temperature.
- Ghorbani-Choghamarani, Arash,Goudarziafshar, Hamid,Zamani, Parisa
-
scheme or table
p. 1207 - 1210
(2012/01/05)
-
- Electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
-
In the present work, the application of electron-deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Taghavi, S. Abdolmanaf
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experimental part
p. 687 - 694
(2012/01/06)
-
- Silylation of alcohols and phenols with hexamethyldisilazane over highly reusable propyl sulfonic acid functionalized nanostructured SBA-15
-
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.
-
experimental part
p. 1864 - 1868
(2012/02/16)
-
- A new crystal engineering approach for the synthesis of {[K.18-Crown-6]I3}n as a nanotube-like and recyclable catalyst for the chemoselective silylation of alcohols
-
Reaction of 18-crown-6 with KI in ethanol solution followed by addition of iodine (I2) afforded a unique triiodide salt with a nanotube-like structure ({[K.18-Crown-6]I3}n). It is shown that this reagent may be used for the chemoselective trimethylsilylation of alcohols. The synthesis of the crystalline reagent is a good example of crystal engineering. Reagent was recycled and reused.
- Zolfigol,Kolvari,Koukabi,Salehzadeh,Chehardoli,Tidmarsh,Niknam
-
experimental part
p. 484 - 494
(2012/06/18)
-
- 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.
-
experimental part
p. 1521 - 1525
(2012/06/18)
-
- A structurally simple self-immolative reagent that provides three distinct, simultaneous responses per detection event
-
A general design is presented for a stimulus-responsive small molecule that is capable of responding to a specific applied chemical or physical signal by releasing two different types of pendant small molecules and a colorimetric indicator simultaneously. A key aspect of this design is the ease with which these reagents are prepared: typically, only four synthetic steps are required. Moreover, the modular construction strategy provides access to stimuli-responsive reagents that are capable of (i) responding to a variety of applied signals and (ii) releasing a number of different small molecules that contain primary alcohols, secondary alcohols, or phenols. These stimuli-responsive reagents are stable under physiological conditions (neither hydrolysis nor thermal degradation of the reagent occurs in significant quantity), and when they are exposed to the appropriate applied signal, they release both pendant small molecules and the colorimetric indicator completely within hours. Finally, unlike other functional groups, such as carbonates, that are used to connect alcohol-bearing molecules to controlled-release reagents, the linkage described in this article increases in hydrolytic stability (rather than decreases) as the pKa of the pendant alcohol decreases (Figure presented).
- Nunez, Sean A.,Yeung, Kimy,Fox, Nicole S.,Phillips, Scott T.
-
experimental part
p. 10099 - 10113
(2012/02/05)
-
- H3PW12O40at the[bmim][FeCl4]: A green catalytic system for alkoxymethylation of alcohols and their one-pot interconversion to acetates and TMS-ethers
-
12-Tungstophosphoric acid immobilized on [bmim][FeCl4] was found to be an efficient catalyst for chemoselective methoxymethylation and ethxoymethylation of alcohols and also one-pot conversion of MOM- or EOM-ethers to their corresponding acetates and TMS-ethers under thermal conditions and microwave irradiation. These procedures were simple, rapid and the corresponding products were obtained in high yields. The catalyst exhibited remarkable reactivity and was reusable.
- Mohammadpoor-Baltork,Moghadam,Tangestaninejad,Mirkhani,Khosropour,Mirjafari
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experimental part
p. 513 - 524
(2012/06/16)
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- [InCl4]: An efficient catalyst-medium for alkoxymethylation of alcohols and their interconversion to acetates and TMS-ethers
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A simple, green and chemoselective method for methoxymethylation and ethoxymethylation of primary and secondary alcohols using a Lewis acidic room temperature ionic liquid, [C4mim][InCl4], as catalyst and reaction medium under ambient temperature, microwave and ultrasonic irradiations is reported. In this catalytic system, the corresponding MOM-and EOM-ethers are obtained in excellent yields and in short reaction times. Furthermore, this catalytic system was used for mild and efficient transformations of these protected alcohols to their corresponding acetates and trimethylsilyl ethers under thermal conditions and microwave and ultrasonic irradiations.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Mirjafari, Arsalan
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experimental part
p. 568 - 579
(2012/05/05)
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- Magnesium hydrogensulfate [Mg(HSO4)2] as an efficient catalyst for the preparation of silyl ethers, dibenzo[a,j]xanthenes, and octahydroxanthene derivatives
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Magnesium hydrogensulfate [Mg(HSO4)2], as a heterogeneous solid acid catalyst, has been used for the mild formation of trimethylsilyl (TMS) ethers from various primary, secondary, and tertiary aliphatic alcohols; aromatic alcohols; a
- Shaterian, Hamid Reza,Doostmohammadi, Razieh,Khorami, Fahimeh,Ghashang, Majid
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experimental part
p. 171 - 180
(2010/04/05)
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- Silylation of alcohols and phenols using hexamethyldisilazane catalyzed by N,N'-diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) under solvent-free and microwave conditions
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N,N'-Diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) (NIBTS) is an effective catalyst for the silylation of alcohols and phenols using hexamethyldisilazane under solvent-free and microwave conditions. Supplemental materials are available for this art
- Ghorbani-Vaghei, Ramin,Malaekehpoor, Seyedeh Mina
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experimental part
p. 582 - 587
(2010/06/15)
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- Silica-bonded S-sulfonic acid as a recyclable catalyst for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS)
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Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in tert-butylmethyl ether, and used as a catalyst for the silylation of hydroxyl groups. A good range of primary, secondary alcohols
- Niknam, Khodabakhsh,Saberi, Dariush,Molaee, Hajar,Zolfigol, Mohammad Ali
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experimental part
p. 164 - 171
(2010/04/04)
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- An expeditious, efficient green methodology for the Boc protection of amines and silyl protection of alcohols over tungstophosphoric acid-doped mesoporous silica
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An efficient, chemoselective and eco-friendly protocol for the protection of amines as N-tert-butylcarbamate using (Boc)2O and protection of alcohols as silyl ether using HMDS over tungstophosphoric acid/SBA15 has been developed. Solventless condition, easy work-up, short reaction time, excellent yields and reusability of the catalyst are the striking features of this methodology which can be considered to be one of the better methods for the protection of amines and alcohols.
- Karmakar, Bikash,Banerji, Julie
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experimental part
p. 3855 - 3858
(2010/08/20)
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- 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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- (PhCH2PPh3)+Br3-: A versatile reagent for the preparation, deprotection, and oxidation of trimethylsilyl ethers
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Benzyltriphenylphosphonium tribromide (BTPTB), as a stable solid reagent, is easily prepared by the reaction of benzyltriphenylphosphonium bromide with Br2. This reagent can be used as an efficient catalyst for the conversion of alcohols to their corresponding trimethylsilyl ethers (TMS ethers) with hexamethyldisilazane (HMDS). Desilylation of TMS ethers is also catalyzed by BTPTB in MeOH at room temperature in high yields. BTPTB is also able to oxidize the TMS ethers to their corresponding carbonyl compounds in a mixture of MeOH/H2O in good to high yields. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
- Shirini,Imanzadeh,Mousazadeh,Mohammadpoor-Baltork,Aliakbar,Abedini
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experimental part
p. 641 - 646
(2010/06/17)
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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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- H5IO6/KI: A new combination reagent for iodination of aromatic amines, and trimethylsilylation of alcohols and phenols through in situ generation of iodine under mild conditions
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A simple method for the in situ generation of iodine using H 5IO6/KI has been developed, and its application in silylation of OH group and iodination of aromatic amines is described.
- Zolfigol, Mohammad Ali,Khazaei, Ardeshir,Kolvari, Eskandar,Koukabi, Nadiya,Soltani, Hamid,Behjunia, Maryam
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experimental part
p. 587 - 594
(2010/06/14)
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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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- [SnIV(TPP)(BF4)2]: An efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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Tin(IV)tetraphenylporphyrinato tetrafluoroborate, [SnIV(TPP)(BF4)2], was used as an efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). High-valent [SnIV(TPP)(BF4)2] catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS-ethers were obtained in high yields and short reaction times at room temperature. While, under the same reaction conditions [SnIV(TPP)Cl2] is less efficient to catalyze these reactions. One important feature of this catalyst is its ability in the 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.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Gharaati, Shadab
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experimental part
p. 212 - 219
(2010/04/04)
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- Homolytic reactions of N-bromohexamethyldisilazane with trialkyl(phenylalkoxy) derivatives of silicon and tin
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The main product of the photoinduced reaction of N- bromohexamethyldisilazane with trialkyl-(benzyloxy)derivatives of silicon and tin R3MO(CH2)nPh (R = Me, Et; M = Si, Sn; n = 1) is N,N-dibenzylidene-C-phenylmethanediamine (hydrobenzamide). For M = Si, with increase of the length of the methylene chain between the oxygen atom and the phenyl group (n = 2, 3), the similar reaction affords the product of bromination of the benzylic carbon atom R3MO(CH2) n-1CHBrPh. For M = Sn, the reaction results in the formation of 2-phenyloxacycloalkanes PhCHO(CH2)n-1. Pleiades Publishing, Ltd., 2010.
- Rakhlin,Podgorbunskaya,Voronkov
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experimental part
p. 930 - 935
(2011/01/09)
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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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- Microwave-assisted rapid and efficient deprotection and direct esterification and silylation of MOM and EOM ethers catalyzed by [Hmim][HSO 4] as a Bronsted acidic ionic liquid
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1-Methylimidazolium hydrogensulfate, [Hmim] [HSO4], a Bronsted acidic room temperature ionic liquid, is used as a catalyst and reaction medium for facile and ecofriendly deprotection of methoxymethyl (MOM) and ethoxymethyl (EOM) ethers to their corresponding alcohols under thermal conditions (Δ) and microwave irradiation (MW). Furthermore, one-pot interconversion to the respective acetates and trimethylsilyl (TMS) ethers was also achieved. Springer-Verlag 2010.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Mirjafari, Arsalan
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experimental part
p. 1083 - 1088
(2012/06/18)
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- 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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