- 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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Read Online
- 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 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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- 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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- 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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- 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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- 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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- Preparation, characterization and use of 3-methyl-1-sulfonic acid imidazolium hydrogen sulfate as an eco-benign, efficient and reusable ionic liquid catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups
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New and novel ionic liquid (3-methyl-1-sulfonic acid imidazolium hydrogen sulfate) is a recyclable and eco-benign catalyst for the chemoselective trimethylsilyl protection of hydroxyl groups under solvent-free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-8 min). The catalyst was characterized by FT-IR, 1H NMR and 13C NMR studies. All the products were extensively characterized by 1H NMR, IR, GC-MS and melting point analyses. A mechanism for the catalytic activity is proposed. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Khaligh, Nader Ghaffari
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experimental part
p. 63 - 70
(2011/12/02)
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- Succinimide-N-sulfonic acid: A mild, efficient, and reusable catalyst for the chemoselective trimethylsilylation of alcohols and phenols
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Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields. Copyright Taylor & Francis Group, LLC.
- Shirini,Khaligh, Nader Ghaffari
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experimental part
p. 2156 - 2165
(2012/04/10)
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- Chemoselective trimethylsilylation of alcohols catalyzed by saccharin sulfonic acid
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Saccharin sulfonic acid was easily prepared by the reaction of saccharin with neat chlorosulfonic acid at room temperature. This reagent is efficiently able to catalyze the chemoselective trimethylsilylation of alcohols with hexamethyldisilazane in the pr
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh
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experimental part
p. 61 - 64
(2010/03/26)
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- Vanadium hydrogen sulfate (I): Chemoselective trimethylsilylation of alcohols and deprotection of trimethylsilyl ethers
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Trimethylsilylation of alcohols with hexamethyldisilazane (HMDS) catalyzed by V(HSO4)3 under mild and completely heterogeneous reaction condition is reported. The method is highly chemoselective for the protection of alcohols in the presence of phenols, amines and thiols. Also, the deprotection of trimethylsilyl ethers is performed in the presence of V(HSO 4)3 at room temperature in good to high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh,Sakhaei, Ali Reza
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experimental part
p. 943 - 946
(2009/12/24)
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