- 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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- BiCl3: A versatile catalyst for the tetrahydropyranylation and depyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric diols
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Bismuth trichloride as mild reagent, has been found to be a worthful catalyst for tetrahydropyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric di-ols. At room temperature the reagent THP(3,4-dihydro-2H-pyran) was successfully employed as pyranylating agent in presence of BiCl3catalyst without the use of a solvent and the yields of the products were found to be 90-96%. Further, the depyranylation of alcohols was achieved in quantitative yield by simple addition of MeOH using the same catalyst. The developed method was showed good chemo-selectivity in symmetrical diols for mono THP protection.
- Vijaya Durga,Balamurali Krishna,Baby Ramana,Santha Kumari,Vijay,Hari Babu
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p. 1030 - 1034
(2017/05/26)
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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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- 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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- Facile O-glycosylation of glycals using Glu-Fe3O4-SO3H, a magnetic solid acid catalyst
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A new glucose derived magnetic solid acid catalyst (Glu-Fe3O4-SO3H) was synthesized in a convenient and ecofriendly manner and well characterized using FTIR, PXRD, EDAX, SEM, and XPS which showed the presence of Fe3/
- Thombal, Raju S.,Jadhav, Vrushali H.
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p. 30846 - 30851
(2016/04/09)
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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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- 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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- Tetrahydropyranylation of alcohols in the presence of a slightly basic, heterogeneous titanium catalyst
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4 ? molecular sieve modified with titanium (IV) is an efficient heterogeneous catalyst for the tetrahydropyranylation of alcohols under mild, slightly basic reaction conditions. The catalyst can be reused with good yield after a simple treatment with dichloromethane.
- Magyar, ágnes,Nagy, Balázs,Hell, Zoltán
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p. 1876 - 1879
(2019/11/28)
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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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- 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
-
experimental part
p. 287 - 296
(2012/05/20)
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- Tetrahydropyranylation of alcohols and phenols catalyzed by a new polystyrene-bound tin(IV) porphyrin
-
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
-
experimental part
p. 95 - 101
(2011/04/22)
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- Solvent-free tetrahydropyranylation of alcohols catalyzed by amine methanesulfonates
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A comparative study of tetrahydropyranylation of alcohols under various solvents or solvent-free conditions using different amine methanesulfonates as catalysts shows that tetrahydropyranyl ethers of alcohols are obtained under solvent-free conditions in good yields using catalytic amounts of triethylenediamine methanesulfonate, 1,6-hexanediamine methanesulfonate, diethylenetriamine methanesulfonate and pyridine methanesulfonate, respectively. The reaction occurs readily in short times at room temperature catalyzed by these catalysts, especially triethylenediamine methanesulfonate. Some of the major advantages of this procedure are that the catalysts are environmentally friendly, highly effective, and easy to prepare and handle. The reaction is also clean and needs no solvent, and the work-up is very simple.
- Wang, Rui,Sun, Mingzhu,Jiang, Heng
-
experimental part
p. 61 - 67
(2012/02/16)
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- Highly efficient tetrahydropyranylation of alcohols and phenols catalyzed by a new and reusable high-valent vanadium(IV) porphyrin
-
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
-
experimental part
p. 1095 - 1102
(2012/03/11)
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- High-valent tin(IV) porphyrin: An efficient and reusable catalyst for tetrahydropyranylation of alcohols and phenols under mild conditions
-
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
-
experimental part
p. 1523 - 1528
(2010/08/04)
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- 1,6-Hexanediamine methanesulfonate: A mild and efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions
-
Various alcohols react with 3,4-dihydro-2 H-pyran under mild conditions using a catalytic amount of 1,6-hexanediamine methanesulfonate. It affords the corresponding tetrahydropyranyl ethers in good yields at a faster rate in the absence of solvent. Taylor & Francis Group, LLC.
- Wang, Rui,Jiang, Heng
-
experimental part
p. 171 - 176
(2012/01/05)
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- Allyl tetrahydropyranyl ether: a versatile alcohol/thiol protecting reagent
-
Allyl tetrahydropyranyl ether (ATHPE) can be used as a versatile protecting reagent. In combination with NBS/I2, O-allyl group can easily be replaced by hydroxyls (including tertiary-OH) or thiols, in the molecules comprising other reactive fun
- Kumar, Brijesh,Aga, Mushtaq A.,Mukherjee, Debaraj,Chimni, Swapandeep S.,Taneja, Subhash C.
-
supporting information; experimental part
p. 6236 - 6240
(2010/01/18)
-
- Copper nitrate/acetic acid as an efficient synergistic catalytic system for the chemoselective tetrahydropyranylation of alcohols and phenols
-
Tetrahydropyranylation of alcohols and phenols was accomplished successfully using copper nitrate and acetic acid as a synergistic catalyst at room temperature under solvent-free condition. Compared with other synergistic catalytic systems, copper nitrate/acetic acid proved to be the most efficient. Both alcohols (primary, secondary, tertiary, benzylic, cyclic, allyl, cinnamyl, and furyl) and phenols reacted smoothly in high yields. Graphical abstract: [Figure not available: see fulltext.]
- Wang, Min,Song, Zhi-Guo,Gong, Hong,Jiang, Heng
-
experimental part
p. 177 - 179
(2010/04/02)
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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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- Copper p-toluenesulfonate/acetic acid: A recyclable synergistic catalytic system for the tetrahydropyranylation of alcohols and phenols
-
Copper p-toluenesulfonate/acetic acid was found to be an efficient, chemoselective synergistic catalytic system, with catalyst loading as low as 0.3 mol% leading to clean, high-yielding tetrahydropyranylation of a variety of alcohols and phenols. By simple phase-separation, copper p-toluenesulfonate can be easily recovered and reused for several times without deterioration in catalytic activity.
- Wang, Min,Song, Zhi-Guo,Jiang, Heng,Gong, Hong
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experimental part
p. 601 - 604
(2009/08/07)
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- Generally applicable organocatalytic tetrahydropyranylation of hydroxy functionalities with very low catalyst loading
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This paper presents the first acid-free, organocatalytic tetrahydropyran and 2-methoxypropene protection of alcohols, phenols, and other ROH derivatives utilizing privileged N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea and a polystyrene-bound analogue. The reactions are broadly applicably (also on preparative scale), in particular, to acid-sensitive substrates such as aldol products, hydroxy esters, acetals, silyl-protected alcohols, and cyanohydrins. The catalytic efficiency is truly remarkably with turnover numbers of 100,000 and turnover frequencies of up to 5700 h-1 at catalyst loadings down to 0.001 mol%. The computationally supported mechanistic interpretation emphasizes the hydrogen bond assisted heterolysis of the alcohol and concomitant preferential stabilization of the oxyanion hole in the transition state. Georg Thieme Verlag Stuttgart.
- Kotke, Mike,Schreiner, Peter R.
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p. 779 - 790
(2008/01/03)
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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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- Tetrahydropyranylation of alcohols and phenols using the synergistic catalyst system, copper(II) chloride-acetic acid
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Copper(II) chloride-acetic acid was found to be an efficient synergistic catalytic system for the tetraphydropyranylation of various alcohols and phenols in high yields at room temperature in short reaction times. Springer-Verlag 2007.
- Wang, Min,Song, Zhi-Guo,Jiang, Heng,Gong, Hong
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p. 599 - 602
(2008/02/03)
-
- Efficient role of ionic liquid (bmim)HSO4 as novel catalyst for monotetrahydropyranylation of diols and tetrahydropyranylation of alcohols
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A simple procedure for the monotetrahydropyranylation of diols and alcohols, in excellent to moderate yields, has been reported using a catalytic amount of the acidic ionic liquid, 1-butyl-3-methylimidazolium hydrogensulphate (bmim)HSO4 under microwave and ultrasonic irradiation. Results have been compared with those obtained by reactions in the absence of these energies, and effectiveness of the recycled ionic liquid has also been studied. Copyright Taylor & Francis Group, LLC.
- Singh, Jasvinder,Gupta, Neeraj,Kad, Goverdhan L.,Kaur, Jasamrit
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p. 2893 - 2900
(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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- 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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- Mild and efficient tetrahydropyranylation of alcohols and dehydropyranylation of THP ethers catalyzed by ferric perchlorate
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A simple, mild and efficient method for tetrahydropyranylation and dehydropyranylation of alcohols in the presence of ferric perchlorate are described.
- Heravi, Majid M.,Behbahani, Farahnaz K.,Oskooie, Hossien A.,Shoar, Rahim Hekmat
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p. 2543 - 2545
(2007/10/03)
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- Bronsted acidic ionic liquids: Fast, mild, and efficient catalysts for solvent-free tetrahydropyranylation of alcohols
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Bronsted acidic ionic liquids as efficient and reusable catalysts for the protection of alcohols as tetrahydropyranyl (THP) ethers under solvent-free conditions at room temperature was investigated. Good to excellent yields were obtained at a faster rate over [BMIm][HSO4] or [BMIm][H2PO4]. Copyright Taylor & Francis, Inc.
- Duan, Zhiying,Gu, Yanlong,Deng, Youquan
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p. 1939 - 1945
(2007/10/03)
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- Simple and facile tetrahydropyranylation of alcohols by use of catalytic amounts of benzyltriphenylphosphonium tribromide
-
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
-
p. 2889 - 2894
(2007/10/03)
-
- Convenient tetrahydropyranylation of alcohols and phenols by catalytic ferric sulfate hydrate (Fe2(SO4)3· xH2O)
-
Ferric sulfate hydrate (Fe2(SO4)3· xH2O) is found to be an efficient heterogeneous catalyst for the tetrahydropyranylation of alcohols and phenols at ambient or near ambient temperature. In addition, selective monotetrahydropyranylation of symmetrical diols is achieved under similar conditions. The deprotection of THP ether and direct transformation of THP ether to the corresponding acetate by Fe 2(SO4)3·xH2O is also studied. The simplicity of manipulation, mild conditions, reusable catalyst, good selectivity, and environment benign characters make this method a good alternative way for the THP protection of alcohols.
- Li, Lingjun,Zhu, Lizhi,Zhang, Xinying,Zhang, Guisheng,Qu, Guirong
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p. 1120 - 1123
(2007/10/03)
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- Phosphorus pentoxide as an efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions
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A facile and efficient method for the preparation of tetrahydropyranyl ethers from alcohols is improved in solvent-free media. These reactions are catalyzed by P2O5 and afford various tetrahydropyranyl ethers in shorter reaction time, with good to excellent yields (75-95%) at room temperature. This method is also compatible with substrates containing acid-sensitive functional groups.
- Eshghi, Hossein,Shafieyoon, Parvaneh
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p. 2149 - 2152
(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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- Zeolite-catalyzed environmentally friendly tetrahydropyranylation of alcohols and phenols
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A simple and environmentally friendly tetrahydropyranylation of various alcohols and phenols at room temperature was elaborated by using a small pore size zeolite. The material is also suitable for the deprotection but with less efficiency.
- Hegedues, Adrienn,Vigh, Ilona,Hell, Zoltan
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p. 4145 - 4152
(2007/10/03)
-
- Solvent-Free Tetrahydropyranylation of Alcohols with Sulfamic Acid as Reusable Catalyst
-
An efficient H2NSO3H-catalyzed solvent-free tetrahydropyranylation of various alcohols at room temperature was investigated. The features of mild conditions, cost-efficient catalyst, simple work-up, and the recyclability of the catalyst were displayed in this article.
- Wang, Bo,Yang, Li-Ming,Suo, Ji-Shuan
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p. 3929 - 3934
(2007/10/03)
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- RuCl3, a mild and efficient catalyst for tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl ethers
-
Catalytic amount of anhydrous ruthenium trichloride in dry acetonitrile catalyzes efficiently tetrahydropyranylation of different types of alcohols to afford the corresponding tetrahydropyranyl ethers in high yields. Deprotection of tetrahydropyranyl ethers can also be achieved efficiently in the presence anhydrous ruthenium trichloride in wet acetonitrile.
- Kazemi,Kiasat,Ebrahimi
-
p. 2888 - 2889
(2007/10/03)
-
- Facile Tetrahydropyranylation of Alcohols and Phenols Using Anhydrous Calcium Chloride under Mild and Neutral Conditions
-
Treatment of 3,4-dihydro-2H-pyran with various alcohols and phenols in the presence of a catalytic amount of anhydrous calcium chloride in dichloromethane furnished tetrahydropyranyl ethers under almost neutral conditions.
- Bandgar, Babasaheb P.,Sadavarte, Vaibhav S.,Uppalla, Lavkumar S.,Patil, Suresh V.
-
p. 425 - 428
(2007/10/03)
-
- Bismuth triflate: An efficient catalyst for the formation and deprotection of tetrahydropyranyl ethers
-
The tetrahydropyranylation of alcohols under solvent-free conditions is efficiently catalyzed by bismuth triflate (0.1 mol %). The experimental procedure is simple and works well with a variety of alcohols and phenols. The catalyst is insensitive to air and small amounts of moisture, easy to handle and relatively nontoxic. The deprotection of THP ethers is also catalyzed by bismuth triflate (1.0 mol %). ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Stephens, Jacqueline R.,Butler, Phillip L.,Clow, Curtis H.,Oswald, Matthew C.,Smith, Russell C.,Mohan, Ram S.
-
p. 3827 - 3831
(2007/10/03)
-
- Solvent-free tetrahydropyranylation (THP) of alcohols and phenols and their regeneration by catalytic aluminum chloride hexahydrate
-
A catalytic amount of aluminum chloride hexahydrate enables solvent-free tetrahydropyranylation (THP) of alcohols and phenols at moderate temperatures. A simple addition of methanol helps to regenerate the corresponding alcohols and phenols, thus rendering these protection and deprotection sequences as very efficient transformations at high substrate to catalyst ratios.
- Namboodiri, Vasudevan V,Varma, Rajender S
-
p. 1143 - 1146
(2007/10/03)
-
- LiBF4: A mild and efficient catalyst for the tetrahydropyranylation of alcohols and their detetrahydropyranylation
-
Catalytic amount of lithium tetrafluoroborate in dry acetonitrile catalyzes an efficient tetrahydropyranylation of different types of alcohols to afford the corresponding tetrahydropyranyl ethers in high yields. Deprotection of tetrahydropyranyl ethers can also be achieved efficiently in the presence of lithium tetrafluoroborate in methanol. The chemoselectivity was observed in the protection of alcoholic function in the presence of phenolic function.
- Kazemi,Kiasat,Ebrahimi
-
p. 2483 - 2487
(2007/10/03)
-
- Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates and their use as catalysts in the solvent-free tetrahydropyranylation of alcohols and phenols
-
Microwave-assisted preparation of dialkylimidazolium tetrachloroaluminates, [CnMIM][A1C14] and their application as recyclable catalysts for the efficient and eco-friendly protection of alcohols as tetrahydropyranyl (THP) ethers are described. The same catalyst can also be utilized for the deprotection of THP ethers.
- Namboodiri, Vasudevan V.,Varma, Rajender S.
-
p. 342 - 343
(2007/10/03)
-
- Microwave accelerated tetrahydropyranylation and detetrahydropyranylation of alcohols, phenols, and thiols catalyzed by hydrated zirconia
-
A solvent free and expeditious method for tetrahydropyranylation and detetrahydropyranylation of alcohols, phenols and thiols is described using hydrated zirconia and 3,4-dihydro-2H-pyran (DHP). A comparison of this microwave-accelerated reaction with conventional heating condition is also presented.
- Gajare, Anil S.,Sabde, Dhananjay P.,Shingare, Murlidhar S.,Wakharkar, Radhika D.
-
p. 1549 - 1555
(2007/10/03)
-
- Protection of alcohols and phenols with dihydropyran and detetrahydropyranylation by ZrCl4
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Alcohols and Phenols are protected efficiently with dihydropyran(DHP) in the presence of catalytic amounts of zirconium tetrachloridein dichloromethane. Deprotection of THP-ethers is also afforded in a methanolic solution at room temperature.
- Rezai, Nasrin,Meybodi, Farhat Alsadat,Salehi, Peyman
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p. 1799 - 1805
(2007/10/03)
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- Stannous chloride dihydrate: A new catalyst for the tetrahydropyranylation of alcohols
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Catalytic Stannous chloride dihydrate in polar aprotic solvents like chloroform efficiently catalyse the tetrahydropyranylation of alcohols in a short time under mild conditions.
- Joju Davis,Bhalerao,Vittal Rao
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p. 1679 - 1686
(2007/10/03)
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- Bis [trinitratocerium (IV)] chromate [ce(NO3)2 Cro4] and tris [trinitratocerium (IV)] paraperiodate [(No3)3Ce]3 H2IO6. Two mild and efficient catalysts for tetrahydrop
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The tetrahydropyranyl derivatives of variety of alcohols are efficiently prepared in the presence of catalytic amounts of [Ce(NO3)2CrO4] and [(NO3)3 Ce]3 H21O6 in mild
- Oskooie,Abaszadeh,Zamani,Heravi
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p. 2281 - 2285
(2007/10/03)
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- Mild and efficient tetrahydropyranylation of alcohols-catalysis by lithium perchlorate in diethyl ether
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Treatment of 3,4-dihydro-2H-pyran 1 with various alcohols 2 - 10 furnished the tetrahydropyranyl ethers 11 - 19 in the presence of 5M lithium perchlorate in diethyl ether (5M LPDE), which is essentially a neutral medium.
- Babu, Boga Sobhana,Balasubramanian, Kalpattu Kuppuswamy
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p. 9287 - 9288
(2007/10/03)
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- Natural kaolinitic clay : A mild and efficient catalyst for the tetrahydropyranylation and trimethylsilylation of alcohols
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Natural kaolinitic clay possessing transition metals such as Fe, Ti in its lattice has been found to catalyze efficiently the protection of a variety of alcohols with 2,3-dihydro-4H-pyran (DHP) and hexamethyldisilazane (HMDS) at ambient conditions.
- Upadhya,Daniel,Sudalai,Ravindranathan,Sabu
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p. 4539 - 4544
(2007/10/03)
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- Dithioacetalization of Carbonyl Compounds and Tetrahydropyranylation of Alcohols over H-Rho Zeolite
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A heterogeneous catalytic method for the dithioacetalization of carbonyl compounds and tetrahydropyranylation of alcohols over H-Rho zeolite is reported.
- Sabde,Naik,Hegde,Hegde
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p. 494 - 495
(2007/10/03)
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- Envirocat EPZG as a new heterogenous catalyst for the solvent-free tetrahydropyranylation of alcohols and phenols
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Envirocat EPZG was used as a solid supported acid catalyst for tetrahydropyranylation of alcohols and phenols in the absence of a solvent. This new method is rapid, efficient and convenient giving the corresponding products in high yields and purity.
- Bandgar,Jagtap,Aghade,Wadgaonkar
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p. 2211 - 2215
(2007/10/02)
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- H-Y zeolite: A mild and efficient catalyst for the tetrahydropyranylation of alcohols
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A variety of hydroxy compounds add to 3,4-dihydro-2H-pyran in the presence of catalytic amounts of H-Y zeolite to afford the corresponding tetrahydropyranyl ethers in excellent yields.
- Kumar,Dinesh,Reddy,Pandey
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p. 1069 - 1070
(2007/10/02)
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