- A mild and efficient chemoselective tetrahydropyranylation of primary alcohols using La(NO3)3·6H2O as a catalyst under solvent-free conditions
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Primary alcohols undergo selective and efficient tetrahydropyranylation in the presence of a catalytic amount of La(NO3)3?6H2O under solvent-free conditions.
- Reddy, T. Srikanth,Ravinder,Suryakiran,Narasimhulu,Mahesh, K. Chinni,Venkateswarlu
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- Highly selective tetrahydropyranylation/dehydropyranylation of alcohols and phenols using porous phenolsulfonic acid-formaldehyde resin catalyst under solvent-free condition
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An efficient protocol for solvent-free chemoselective tetrahydropyranylation/depyranylation of alcohols and phenols is reported herein using mesoporous Phenolsulfonic Acid Formaldehyde Resins as a heterogeneous acid catalyst. The catalyst successfully performed chemoselective protection and deprotection reactions of a wide range of substrates ranging from primary to secondary and tertiary alcohols and also phenols. The reactions were carried out at ambient temperature under solvent-free condition (SolFC) which resulted in high yields within a very short time. FT-IR, TEM, SEM, EDS and TG-DSC analysis techniques were employed to characterize the synthesized polymeric catalyst. The chemoselective nature of our method was confirmed using 13C DEPT-135 NMR studies. The polymer catalyst was found to be recoverable even after 10th catalytic cycle without much depreciation in its activity. The heterogeneity of the catalyst was verified by hot filtration method. Good yield, energy and cost- effective method, solvent-free protocol, mild reaction conditions, no inert atmosphere, metal-free heterogeneous polymer catalyst and excellent recoverability of the catalyst are notable milestones of the reported protocol.
- Rajkumari, Kalyani,Laskar, Ikbal Bahar,Kumari, Anupama,Kalita, Bandita,Rokhum, Lalthazuala
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- Cyclopropenium Enhanced Thiourea Catalysis
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An integral part of modern organocatalysis is the development and application of thiourea catalysts. Here, as part of our program aimed at developing cyclopropenium catalysts, the synthesis of a thiourea-cyclopropenium organocatalyst with both cationic hydrogen-bond donor and electrostatic character is reported. The utility of the this thiourea organocatalyst is showcased in pyranylation reactions employing phenols, primary, secondary, and tertiary alcohols under operationally simple and mild reaction conditions for a broad substrate scope. The addition of benzoic acid as a co-catalyst facilitating cooperative Br?nsted acid catalysis was found to be valuable for reactions involving phenols and higher substituted alcohols. Mechanistic investigations, including kinetic and 1H NMR binding studies in conjunction with density function theory calculations, are described that collectively support a Br?nsted acid mode of catalysis.
- Smajlagic, Ivor,Durán, Rocio,Pilkington, Melanie,Dudding, Travis
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supporting information
p. 13973 - 13980
(2018/11/21)
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- Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents
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The application of heterogeneous catalysis and green solvents to the set up of widely employed reactions is a challenge in contemporary organic chemistry. We applied such an approach to the synthesis and further conversion of tetrahydropyranyl ethers, an important class of compounds widely employed in multistep syntheses. Several alcohols and phenols were almost quantitatively converted into the corresponding tetrahydropyranyl ethers in cyclopentyl methyl ether or 2-methyltetrahydrofuran employing NH4HSO4 supported on SiO2 as a recyclable acidic catalyst. Easy work up of the reaction mixtures and the versatility of the solvents allowed further conversion of the reaction products under one-pot reaction conditions.
- Azzena, Ugo,Carraro, Massimo,Modugno, Gloria,Pisano, Luisa,Urtis, Luigi
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supporting information
p. 1655 - 1659
(2018/07/25)
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- Magnetic Fe3O4@silica sulfuric acid nanoparticles promoted regioselective protection/deprotection of alcohols with dihydropyran under solvent-free conditions
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Protection (and deprotection) of hydroxyl groups via tetrahydropyranylation was carried out effectively using a catalytic amount of Fe3O4 supported silica sulphuric acid nanoparticles (Fe3O4@SiO2@SO3H) under solvent-free conditions. The synthesized nanocatalyst was characterized by XRD, TEM, FT-IR etc. A wide range of tetrahydropyranylated alcohol derivatives were synthesized using this heterogeneous magnetic nanocatalyst within 10-20 min with high yields. In addition, tetrahydropyranyl ethers could also be deprotected to the parent alcoholic compounds in the presence of MeOH using the same catalyst. After completion of the reactions, the catalyst was easily separated from the reaction medium using an external magnet, which ameliorated the overall synthetic process. The catalyst was recovered and reused for five successive reactions without any appreciable loss in its activity. Mild reactions conditions, operational simplicity, solvent free conditions, high selectivity, easy recyclability of the magnetic nanocatalyst, and high yields can be considered as the advantageous features of our procedure.
- Rajkumari, Kalyani,Kalita, Juri,Das, Diparjun,Rokhum, Lalthazuala
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p. 56559 - 56565
(2017/12/27)
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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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- Tetrahydropyranylation of alcohols and phenols catalyzed by a new multi-wall carbon nanotubes-bound tin(IV) porphyrin
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Abstract: In the present study, tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) using tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], and tetrakis(p-aminophenyl)porphyrinatotin(IV) tetrafluoroborate, [SnIV(TNH2PP)(BF4)2], supported on multi-wall carbon nanotubes as new catalytic systems is investigated. These new catalysts, [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT], were characterized using elemental analysis, FT-IR spectroscopic techniques, scanning electron microscopy and diffuse reflectance UV–Vis spectroscopic methods. In these catalytic systems, an optimization on the amounts of catalysts and amount of DHP was done in the tetrahydropyranylation of alcohols and phenols with DHP and the best outcomes were received in the presence of 0.01?mmol (40?mg) of [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT] with 2?mmol of DHP. Efficiency and reusability are two important features of these new heterogenized catalysts for tetrahydropyranylation of primary, secondary and tertiary alcohols as well as phenols at room temperature. These catalysts were recovered several times with no loss on their initial activity, which indicates their high reusability and stability. Graphical Abstract: In the present study, tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) using tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], and tetrakis(p-aminophenyl)porphyrinatotin(IV) tetrafluoroborate, [SnIV(TNH2PP)(BF4)2], supported on multi-wall carbon nanotubes as new catalytic systems is investigated. These new catalysts, [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT], were characterized using elemental analysis, FT-IR spectroscopic techniques, scanning electron microscopy and diffuse reflectance UV–Vis spectroscopic methods. In these catalytic systems, an optimization on the amounts of catalysts and amount of DHP was done in the tetrahydropyranylation of alcohols and phenols with DHP and the best outcomes were received in the presence of 0.01?mmol (40?mg) of [SnIV(TNH2PP)(OTf)2@MWCNT] and [SnIV(TNH2PP)(BF4)2@MWCNT] with 2?mmol of DHP. Efficiency and reusability are two important features of these new heterogenized catalysts for tetrahydropyranylation of primary, secondary and tertiary alcohols as well as phenols at room temperature. These catalysts were recovered several times with no loss on their initial activity, which indicates their high reusability and stability. [Figure not available: see fulltext.].
- Gharaati, Shadab,Kargar, Hadi,Falahati, Ali Mohammad
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p. 1169 - 1178
(2017/05/15)
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- Single-Electron-Transfer Strategy for Reductive Radical Cyclization: Fe(CO)5 and Phenanthroline System
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An electron-transfer strategy using low-valent iron pentacarbonyl [Fe(CO)5] to generate radical species from alkyl iodides was achieved. A range of pyrrolidines, tetrahydrofurans, and carbocycles were synthesized via 5-exo cyclization reactions of alkyl radical intermediates generated by electron transfer from a system involving Fe(CO)5, 1,10-phenanthroline, and diisopropylamine. Moreover, tandem addition reactions with Michael acceptors were also explored. Photophysical and electrochemical studies support a mechanism that involves electron transfer from the low-valent Fe reductant to alkyl iodide.
- Hwang, Joon Young,Baek, Jong Hwa,Shin, Tae Il,Shin, Jung Ha,Oh, Jae Won,Kim, Kwang Pyo,You, Youngmin,Kang, Eun Joo
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supporting information
p. 4900 - 4903
(2016/10/18)
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- Supported N-propylsulfamic acid onto Fe3O4 magnetic nanoparticles as a reusable and efficient nanocatalyst for the protection/deprotection of hydroxyl groups and protection of aldehydes
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N-propylsulfamic acid supported onto Fe3O4 magnetic nanoparticles (MNPs-PSA) as an efficient and magnetically reusable nanocatalyst has been reported for the tetrahydropyranylation/depyranylation of a wide variety of alcohols and phenols by changing the solvent medium. Also, the protection of aldehydes as acylals using Ac2O in the presence of catalytic amount MNPs-PSA in good to high yields at room temperature under solvent-free conditions is described. After completing the reaction, the catalyst was easily separated from the reaction mixture with the assistance of an external magnetic field and reused for several consecutive runs without significant loss of their catalytic efficiency.
- Rostami, Amin,Tahmasbi, Bahman,Abedi, Fatemeh
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p. 3689 - 3701
(2016/04/05)
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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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- An efficient Br?nsted–Lewis acidic ionic liquid catalyzed tetrahydropyranylation of alcohols
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An imidazolium based Br?nsted–Lewis acidic ionic liquid has been shown to be an excellent catalyst and reaction medium for the tetrahydropyranylation of various alcohols in good to excellent yields with short reaction times. Selective protection of benzyl
- Azizi, Najmedin,Abdoli-Senejani, Masumeh,Abbasi, Faezeh
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p. 5009 - 5011
(2016/10/24)
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- Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst
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Titanium(IV) salophen trifluoromethanesulfonate, [TiIV(salophen)(OSO2CF3)2], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright
- Yadegari, Maryam,Moghadam, Majid
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p. 872 - 875
(2016/09/20)
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- Sulfonic acid-functionalized LUS-1: an efficient catalyst for tetrahydropyranylation/depyranylation of alcohols
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Efficient acidic functionalization of mesoporous silica LUS-1 (Laval University Silica) and its application as a recyclable heterogeneous catalyst for DHP (3,4-dihydro-2H-pyran) protection of alcohols and the subsequent removal of the corresponding protecting group have been reported. This green method offers a number of advantages such as short reaction time, good yields of protection and deprotection, simple work-up procedure, recyclable catalyst, and environmentally friendly conditions.
- Rahimifard, Mahshid,Mohammadi Ziarani, Ghodsi,Badiei, Alireza
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p. 6327 - 6336
(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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- 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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- {[[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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- Solvent-free NaHSO4-SiO2-catalyzed efficient tetrahydropyranylation of alcohols and phenols
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A simple and efficient tetrahydropyranylation of alcohols and phenols has been developed using NaHSO4-SiO2 (0.5 mol%) as a catalyst under solvent-free conditions to yield corresponding tetrahydropyranyl ethers in excellent yields.
- Kinfe, Henok H.,Mebrahtu, Fanuel M.,Moshapo, Paseka T.
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p. 1237 - 1242
(2013/04/10)
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- Short communication: Catalytic tetrahydropyranylation of phenols and alcohols using vanadium(V)-substituted polyoxomolybdates
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Alcohols and phenols were tetrahydropyranylated in the presence of H 7[PMo8V4O40] in good to excellent yields in acetonitrile and under solventfree reaction conditions. A mild and convenient method for the formation and deprotection of ethers (THP ethers) is described. The formation of THP ethers from the corresponding alcohols was accomplished in the presence of acid-sensitive functional groups.
- Gharib, Ali,Jahangir, Manouchehr
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experimental part
p. 287 - 296
(2012/05/20)
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- Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for tetrahydropyranylation of alcohols and phenols
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A new, simple and highly chemoselective method for tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in the presence of polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid catalyst at room temperature is presented.
- Rahmatpour, Ali
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p. 66 - 71,6
(2012/12/11)
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- Simple and efficient method for tetrahydropyranylation of alcohols and phenols by using silica supported sodium hydrogen sulphate as a catalyst
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A Simple and efficient process for tetrahydropyranylation of alcohols and phenols has been developed by reacting with dihydropyran at room temperature in presence of catalytic amount of silica supported sodium hydrogen sulphate.
- Ravi Kumar,Satyanarayana,Srinivasa Reddy
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experimental part
p. 3876 - 3878
(2012/09/21)
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- Mild and efficient chemoselective tetrahydropyranylation of alcohols using bronsted acidic ionic liquid as catalyst under solvent-free conditions
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A straightforward and efficient method for preparation of morpholinium bisulfate ([mroH]HSO4) as a novel acidic ionic liquid is reported. The application of this efficient and inexpensive acidic ionic liquid catalyst for tetrahydropyranylation of alcohols under mild and solvent-free conditions at room was investigated.
- Hajipour, Abdol R.,Nasresfahani, Zahra
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experimental part
p. 1995 - 2006
(2012/06/04)
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- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
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In continuation of research to explore the applied potential of DMF-like ionic liquid, the ionic liquid version of N,N-dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF-like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF-like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF-like ionic liquid has been coined that is DMF-like "multipurpose" ionic liquid. Copyright
- Hullio, Ahmed Ali,Mastoi
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scheme or table
p. 1647 - 1657
(2012/09/21)
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- Synthesis of sulfonic acid functionalized carbon catalyst from glycerol pitch and its application for tetrahydropyranyl protection/deprotection of alcohols and phenols
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A novel carbon catalyst with -SO3H, -OH and -COOH functional groups was prepared from glycerol pitch by in situ partial carbonization and sulfonation with sulfuric acid. The activity of the catalyst was investigated through tetrahydropyranylation and dehydropyranylation of a wide variety of alcohols and phenols at room temperature by changing the solvent medium from dichloromethane to methanol. Excellent yields, short reaction times, easy and quick isolation of the products and reusability of the catalyst are the main attractions of this method. The novel carbon catalyst holds great potential in the green chemical processes.
- Prabhavathi Devi,Gangadhar,Siva Kumar,Shiva Shanker,Prasad,Sai Prasad
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experimental part
p. 96 - 100
(2011/10/05)
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- Tetrahydropyranylation of alcohols and phenols catalyzed by a new polystyrene-bound tin(IV) porphyrin
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In the present work, tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) catalyzed by tetrakis(p-aminophenyl) porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH 2PP)(OTf)2], supported on chloromethylated polystyrene is reported. The prepared catalyst was characterized by elemental analysis, FT-IR and diffuses reflectance UV-Vis spectroscopic methods. This new heterogenized catalyst was found as efficient and reusable catalyst for tetrahydropyranylation of primary, secondary and tertiary alcohols as well as phenols at room temperature.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Gharaati, Shadab
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experimental part
p. 95 - 101
(2011/04/22)
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- [H2-Cryptand 222]2+(Br3-) 2 as a tribromide-type catalyst for the trimethylsilylation/ tetrahydropyranylation of alcohols
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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
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experimental part
p. 127 - 131
(2012/06/18)
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- Highly efficient tetrahydropyranylation of alcohols and phenols catalyzed by a new and reusable high-valent vanadium(IV) porphyrin
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In the present work, the catalytic activity of high-valent tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) is reported. This new electron-deficient V(IV) compound was used as a highly efficient catalyst for pyranylation of primary (aliphatic and benzylic), sterically-hindered secondary and tertiary alcohols with DHP. Tetrahydropyranylation of phenols with DHP was also performed to afford the desired THP-ethers. The chemoselectivity of this method was also investigated. The results indicated that primary alcohols are more reactive in the presence of secondary and tertiary alcohols and phenols. This catalyst was reused several times without loss of its activity.
- Abdolmanaf Taghavi,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza
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experimental part
p. 1095 - 1102
(2012/03/11)
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- Poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′- tetrabromobenzene-1, 3-disulfonamide as new efficient reagents for conversion of alcohols to THP ethers and aldehydes to oxazoline compounds
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This paper is concerned with an easy preparation of THP ethers from primary, secondary and tertiary alcohols and oxazoline compounds from various aldehydes using poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] as new and efficient reagents under ambient conditions without over-oxidation.
- Ghorbani-Vaghei,Akbari-Dadamahaleh,Amiri
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experimental part
p. 301 - 307
(2010/09/03)
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- High-valent tin(IV) porphyrin: An efficient and reusable catalyst for tetrahydropyranylation of alcohols and phenols under mild conditions
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In this paper, rapid and highly efficient tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in the presence of catalytic amounts of high-valent tin (IV) tetraphenylporphyrinato trifluoromethanesufonate, [SnIV(TPP)(OTf)2] is reported. In this catalytic system, primary, secondary and tertiary alcohols as well as phenols were converted to their corresponding tetrahydropyranyl ethers (THP-ethers) in excellent yields and short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective tetrahydropyranylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times in the protection reactions without loss of its catalytic activity.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Gharaati, Shadab
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experimental part
p. 1523 - 1528
(2010/08/04)
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- A highly efficient and ecofriendly procedure for tetrahydropyranylation of alcohols and phenols in the presence of in-situ generated I2 under heterogeneous and neutral conditions
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Molecular iodine generated in situ from Fe(NO3) 3?9H2O/NaI acts as a highly efficient catalyst for tetrahydropyranylation of various alcohols and phenols with 3,4-dihydro-2H-pyran in almost quantitative yields. The reaction occurs rapidly in dichloromethane at room temperature, and use of toxic molecular iodine is avoided.
- Rostami, Amin,Rahmati, Sadegh,Khazaei, Ardeshir
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experimental part
p. 663 - 667
(2010/05/18)
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- Tetrahydropyranylation of alcohols under solvent-free conditions
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A green, efficient, and large-scale method for tetrahydropyranylation of alcohols in the presence of a catalytic amount of pyridinium chloride at room temperature under solvent-free conditions is reported. Copyright Taylor & Francis Group, LLC.
- Hajipour, Abdol R.,Kargosha, Majid,Ruoho, Arnold E.
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experimental part
p. 1084 - 1091
(2009/09/08)
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- AI(OTf)3 - A highly efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions
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A simple and highly efficient method has been developed for the tetrahydropyranylation of alcohols by their reaction with 3,4-dihydro-2H-pyran (DHP) using a catalytic amount (0.01-1 mol%) of aluminium triflate under solvent-free conditions. The effect of various factors like temperature, amount of the catalyst, and molar ratio of substrates on the reaction conditions has also been studied. The comparative study of tetrahydropyranylation of benzyl alcohol using various catalysts including some reported ones shows the efficiency of this catalyst.
- Kamal, Ahmed,Naseer A Khan,Srikanth,Srinivasa Reddy
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scheme or table
p. 1099 - 1104
(2009/03/11)
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- Efficient and ecofriendly protocol for tetrahydropyranylation/ depyranylation of alcohols in the presence of tin(II) chloride dihydrate
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A mild, efficient, and solvent-free protocol for tetrahydropyranylation of alcohols in the presence of a catalytic amount of SnCl2·2H2O is reported. Simple filtration of the reaction mixture through a short silica-gel pad gives the pure products in excellent yields. Depyranylation can also be achieved by adding methanol under similar reaction conditions. Copyright Taylor & Francis Group, LLC.
- Gogoi, Dipankoj,Baruah, Nabajyoti,Bez, Ghanashyam
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p. 595 - 599
(2007/10/03)
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- Silica triflate as a new, mild and efficient catalyst for tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl ethers
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Silica triflate, a new stable derivative of silica gel, is easily prepared by the reaction of silica gel with trifluoromethanesulfonyl chloride. Silica triflate acts as a highly effective and reusable catalyst for tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl ethers under mild and completely heterogeneous reaction conditions.
- Shirini,Marjani,Nahzomi, H. Taherpour
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p. 2235 - 2240
(2008/02/08)
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- N-Bromosuccinimide (NBS): A mild and efficient catalyst for tetrahydropyranylation of alcohols and phenols under solvent-free conditions
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Different types of alcohols and phenols are tetrahydropyranylated in the presence of NBS catalyst in good to excellent yields under mild, neutral and solvent-free conditions.
- Khazaei, Ardeshir,Rostami, Amin,Raiatzadeh, Ayeh
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p. 1029 - 1032
(2008/03/11)
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- Silica-supported perchloric acid (HClO4-SiO2): A versatile catalyst for tetrahydropyranylation, oxathioacetalization and thioacetalization
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A simple and convenient synthetic protocol for the protection of hydroxyl group as tetrahydropyranyl ether as well as carbonyl functionality as oxathioacetal and thioacetal has been achieved using a catalytic amount of silica-supported perchloric acid und
- Khan, Abu T.,Parvin, Tasneem,Choudhury, Lokman H.
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p. 2497 - 2502
(2008/02/03)
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- Efficient and convenient procedure for protection of hydroxyl groups to the THP, THF and TMS ethers and oxidation of these ethers to their aldehydes or ketones in [BPy]FeCl4 as a low cost room temperature ionic liquid
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Alcohols were converted to the corresponding THP, THF or TMS ethers in high to excellent yields in 1-n-butylpyridinium chloroferrate media as a stable and low cost room temperature ionic liquid. In addition, oxidation of these ethers to their aldehydes or ketones without any overoxidation reactions in this ionic liquid was also performed.
- Khosropour, Ahmad R.,Khodaei, Mohammad M.,Ghaderi, Sattar
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p. 326 - 330
(2007/10/03)
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- Solvent-free carbon-oxygen bond formation catalysed by CeCl 3·7H2O/NaI: Tetrahydropyranylation of hydroxy groups
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An efficient and highly chemoselective method fo the protection of free hydroxy compounds with 3,4-dihydro-2H-pyran is reported. Since the deprotection of THP-ethers occurs very readily at room temperature, the successful use of this type of protecting group depends only upon how readily it can be introduced. For this we have examined the tetrahydropyranylation of alcohols and phenols catalysed by the CeCl3·7H2O/NaI system surface under solvent-free conditions. The reaction presents the advantage of being performable under extremely mild conditions by use of catalytic amounts of an interesting Lewis acidic system consisting of the CeCl3· 7H2O/NaI catalyst combination, which can be easily separated from the reaction mixture. The advantages of this procedure, which utilizes cheap and "lfriendly" reagents, over the previously reported ones are discussed. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Bartoli, Giuseppe,Giovannini, Riccardo,Giuliani, Arianna,Marcantoni, Enrico,Massaccesi, Massimo,Melchiorre, Paolo,Paoletti, Melissa,Sambri, Letizia
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p. 1476 - 1482
(2007/10/03)
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- Efficient method for tetrahydropyranylation of alcohols and phenols and deprotection of THP ethers using H14[NaP5W 30O110] as a Green Catalyst
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A simple and effective method for tetrahydropyranylation of alcohols and phenols and the regeneration of THP ethers using a catalytic amount of H 14[NaP5W30O110] is reported. Copyright Taylor & Francis Group, LLC.
- Heravi, Majid M.,Haghighi, Masoumeh,Derikvand, Fatemeh,Bamoharram, Fatemeh F.
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p. 3103 - 3107
(2007/10/03)
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- A mild and efficient method for tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols by BiOClO4.xH 2O (or) BiONO3
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A mild and efficient method for the protection of alcohols and phenols as tetrahydropyranyl ethers 3a-k and their deprotection at room temperature using BiOClO4.xH2O (or) BiONO3 as catalyst is described.
- Thirupathi Reddy,Narsimha Reddy,Sunil Kumar,Srinivasulu,Rajitha
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p. 2396 - 2398
(2007/10/03)
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- A mild and efficient tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols by VCl3
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Vanadium chloride is found to be an efficient catalyst for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols, giving good yields at room temperature and short reaction times. 2005 Springer Science+Business Media, Inc.
- Narsimha Reddy,Sunil Kumar,Kumar,Srinivasulu,Thirupathi Reddy,Rajitha
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p. 1371 - 1373
(2007/10/03)
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- Simple and facile tetrahydropyranylation of alcohols by use of catalytic amounts of benzyltriphenylphosphonium tribromide
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An efficient and mild system for protection of a variety of alcohols with 3,4-dihydro-2H-pyran (DHP) in the presence of catalytic amounts of benzyltriphenyl-phosphonium tribromide (BTPTB) (1) gives the corresponding tetrahydropyan ethers (ROTHP) in dichloromethane. The experimental procedure is simple, and the products are straightforwardly isolated in high to excellent yields. Copyright Taylor & Francis, Inc.
- Hajipour,Pourmousavi,Ruoho
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p. 2889 - 2894
(2007/10/03)
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- Chemoselective tetrahydropyranylation of primary alcohols under freezing water pressure
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A highly efficient environmentally friendly method for selective tetrahydropyranylation of primary alcoholic groups under pressure exerted by freezing water has been described.
- Boruwa, Joshodeep,Bhuyan, Ranjana,Gogoi, Naminita,Barua, Nabin C.
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p. 331 - 334
(2007/10/03)
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- Chemoselective tetrahydropyranylation of alcohols and phenols using polystyrene supported aluminium chloride as a catalyst
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A simple, efficient and highly chemoselective method for tetrahydropyranylation of alcohols and phenols has been developed by their reaction with 3,4-dihydro-2H-pyran at room temperature in the presence of a catalytic amount of polystyrene supported AlCl3. The method is also highly selective for monoprotection of symmetrical diols.
- Tamami, Bahman,Parvanak Borujeny, Kaveh
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p. 715 - 718
(2007/10/03)
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- Efficient tetrahydropyranylation of alcohols and detetrahydropyranylation reactions in the presence of catalytic amount of trichloroisocyanuric acid (TCCA) as a safe, cheap industrial chemical
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Preparation and cleavage of THP ethers of different hydroxy functional groups are easily and efficiently performed in the presence of trichloroisocyanuric acid (TCCA) in the absence of solvent with high yields.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
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p. 3623 - 3630
(2007/10/03)
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- A simple and efficient tetrahydropyranylation using N-bromosuccinamide
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Tetrahydropyranylation of hydroxyl groups of alcohols and phenols has been achieved easily and efficiently using N-bromosuccinamide at room temperature.
- Das, Biswanath,Reddy, M. Ravinder,Ravindranath,Reddy, V. Saidi,Venkateshwarlu
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p. 1711 - 1712
(2007/10/03)
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- Chemoselective tetrahydropyranylation of alcohols and their detetrahydropyranylation using silicasulphuric acid as a reusable catalyst
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A simple, mild, and efficient protocol for chemoselective protection of alcohols over phenols as tetrahydropyranyl ethers and their deprotection using silicasulphuric acid as a reusable solid acid catalyst is described.
- Pore,Desai, Uday V.,Mane,Wadgaonkar
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p. 2135 - 2142
(2007/10/03)
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- The use of basic resin in the preparation of tetrahydropyranyl derivatives of alcohols and phenols
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A quick and efficient method for the preparation of tetrahydropyranyl (THP) derivatives of phenols and alcohols using a basic resin IRA-400 (iodide) is described.
- Chaturvedi, Devdutt,Kumar, Atul,Ray
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p. 437 - 438
(2007/10/03)
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- Cupric sulfate pentahydrate (CuSO4·5H2O): A mild and efficient catalyst for tetrahydropyranylation/depyranylation of alcohols and phenols
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Various alcohols and phenols can be smoothly converted to the corresponding THP ethers using 20 mol % CuSO4·5H2O under mild reaction conditions at room temperature. Some of the major advantages of this procedure are nonaqueous work-up, very good yields, less expensive catalyst and compatibility with other protecting groups.
- Khan, Abu T.,Choudhury, Lokman H.,Ghosh, Subrata
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p. 7891 - 7894
(2007/10/03)
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