- Copper-Catalyzed Oxidative Acetalization of Boronic Esters: An Umpolung Strategy for Cyclic Acetal Synthesis
-
A protocol for the acetalization of boronic esters is described. The reaction is catalyzed by copper, and the conditions proved to be mild and were amenable to a variety of functional groups. We expanded the Chan-Lam coupling to include C(sp3) nucleophiles and converted them into corresponding acetals. This method allows for the orthogonal acetalization of substrates with reactive, acid-sensitive functional groups.
- Miller, Eric M.,Walczak, MacIej A.
-
p. 8230 - 8239
(2020/07/15)
-
- BiCl3: A versatile catalyst for the tetrahydropyranylation and depyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric diols
-
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
-
p. 1030 - 1034
(2017/05/26)
-
- Magnetic nanoparticle-supported DABCO tribromide: A versatile nanocatalyst for the synthesis of quinazolinones and benzimidazoles and protection/deprotection of hydroxyl groups
-
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
-
p. 9033 - 9040
(2017/08/29)
-
- Facile O-glycosylation of glycals using Glu-Fe3O4-SO3H, a magnetic solid acid catalyst
-
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.
-
p. 30846 - 30851
(2016/04/09)
-
- Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst
-
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
-
p. 872 - 875
(2016/09/20)
-
- P4VPy–CuO nanoparticles as a novel and reusable catalyst: application at the protection of alcohols, phenols and amines
-
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
-
p. 1699 - 1712
(2016/07/27)
-
- 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
-
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
-
p. 3689 - 3701
(2016/04/05)
-
- Introduction of a New Ionic Liquid Catalyst for the Trimethylsilyl and Tetrahydropyranyl Protection of Alcohols
-
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
-
p. 1912 - 1921
(2015/12/12)
-
- 3,5-Dinitrobenzoic acid catalyzed synthesis of 2,3-unsaturated O- and S-glycosides and tetrahydropyranylation of alcohols and phenols
-
A simple procedure for the synthesis of 2,3-unsaturated glycosides in acetonitrile and tetrahydropyranylation of alcohols and phenols in dichloromethane in the presence of 3,5-dinitrobenzoic acid is described. A variety of alcohols and thiols are reacted with glycals to give the desired products in high yields with high α-selectivity.
- Bodipati, Naganjaneyulu,Palla, Srinivasa Rao,Komera, Venkateshwarlu,Peddinti, Rama Krishna
-
supporting information
p. 6878 - 6881
(2015/02/02)
-
- {[[K.18-Crown-6]Br3}n: A tribromide catalyst for the catalytic protection of amines and alcohols
-
{[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
-
p. 1730 - 1733
(2013/10/21)
-
- Solvent-free acetylation and tetrahydropyranylation of alcohols catalyzed by recyclable sulfonated ordered nanostructured carbon
-
Rapid and practical green acetylation and tetrahydropyranylation routes of structurally diverse alcohols and phenols were applied under solvent-free reaction conditions providing excellent yields, using catalytic amounts of environmentally friendly sulfonated ordered nanoporous carbon (CMK-5-SO 3H). Non-toxic nature of the catalyst, its easy handling, recovery and reusability, and the absence of any solvent characterize the presented procedures as efficient methods. These procedures provide methods for the separation of the product by simple filtration.
- Zareyee, Daryoush,Alizadeh, Parastoo,Ghandali, Mohammad S.,Khalilzadeh, Mohammad A.
-
p. 713 - 721
(2013/07/26)
-
- Short communication: Catalytic tetrahydropyranylation of phenols and alcohols using vanadium(V)-substituted polyoxomolybdates
-
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)
-
- Polystyrene-supported GaCl3: A new, highly efficient and recyclable heterogeneous Lewis acid catalyst for tetrahydropyranylation of alcohols and phenols
-
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
-
p. 66 - 71,6
(2012/12/11)
-
- Tetrahydropyranylation of alcohols and phenols using polystyrene supported lewis acids as catalysts
-
Polystyrene supported TiCl4 (Ps-TiCl4) and polystyrene supported FeCl3(Ps-FeCl3) were prepared by coordinating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyridine-adsorbed IR. The loading of Ps-TiCl4 and Ps-FeCl3 were 0.35 and 0.3 mmol·g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity. Polystyrene supported TiCl4 (Ps-TiCl4) and polystyrene supported FeCl3(Ps-FeCl 3) were prepared by coordinating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyridine-adsorbed IR. The loading of Ps-TiCl4 and Ps-FeCl3 were 0.35 and 0.3 mmol·g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity. Copyright
- Zhang, Yi,Dou, Qianqian,Liu, Yuan,Dai, Liyan,Wang, Xiaozhong,Chen, Yingqi
-
p. 2567 - 2572
(2013/01/15)
-
- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
-
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
-
scheme or table
p. 1647 - 1657
(2012/09/21)
-
- Synthesis of sulfonic acid functionalized carbon catalyst from glycerol pitch and its application for tetrahydropyranyl protection/deprotection of alcohols and phenols
-
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
-
experimental part
p. 96 - 100
(2011/10/05)
-
- 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)
-
- Solvent-free tetrahydropyranylation of alcohols catalyzed by amine methanesulfonates
-
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)
-
- [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)
-
- 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)
-
- 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)
-
- 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
-
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
-
experimental part
p. 301 - 307
(2010/09/03)
-
- 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)
-
- Metal benzenesulfonates/acetic acid mixtures as novel catalytic systems: Application to the protection of a hydroxyl group
-
A surprising synergistic effect has been discovered in mixtures of metal benzenesulfonates (Co, Al, Ni, Zn, Cd, Pr, La, Cu, Mn) and acetic acid, leading to active catalytic systems for the tetrahydropyranylation of alcohols and phenols to produce tetrahydropyranyl ethers. All reactions proceed mildly and efficiently with moderate to high yields at room temperature without solvent. After the reaction, the metal benzenesulfonate can be easily recovered and reused many times. The efficiency of these systems might result from the "double activation" by Bronsted and Lewis acid catalysis.
- Wang, Min,Gao, Jingjing,Song, Zhiguo
-
experimental part
p. 1349 - 1352
(2011/01/11)
-
- Tetrahydropyranylation of alcohols over modified zeolites
-
A catalytic amount of Moβ enables tetrahydropyranylation of various alcohols, phenols and naphthols under mild reaction conditions at room temperature in moderate to excellent yields within short reaction times is presented. The catalyst Moβ is reused without significant loss of activity. The product isolation is simple and environmentally benign.
- Narender,Suresh Kumar Reddy,Arun Kumar,Rohitha,Kulkarni
-
experimental part
p. 175 - 178
(2010/11/05)
-
- 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)
-
- Carbon tetrabromide/sodium triphenylphosphine-m-sulfonate (TPPMS) as an efficient and easily recoverable catalyst for acetalization and tetrahydropyranylation reactions
-
A solid complex, conveniently prepared from carbon tetrabromide and sodium triphenylphos-phine-m-sulfonate (TPPMS), can be used as an easily recoverable catalyst for the selective acetalization of aldehydes and tetrahydropyranylation of alcohols. The catalyst can be recovered by simple pre-cipitation with ether and can be reused at least 7 times without loss of catalytic activity.
- Huo, Congde,Chan, Tak Hang
-
experimental part
p. 1933 - 1938
(2011/02/28)
-
- 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
-
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
-
experimental part
p. 663 - 667
(2010/05/18)
-
- 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 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
-
experimental part
p. 601 - 604
(2009/08/07)
-
- AI(OTf)3 - A highly efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions
-
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
-
scheme or table
p. 1099 - 1104
(2009/03/11)
-
- Parallel synthesis in an EOF-based micro reactor
-
We present herein a micro reactor set-up that enables parallel syntheses to be performed under electroosmotic flow conditions. The Royal Society of Chemistry.
- Wiles, Charlotte,Watts, Paul
-
p. 4928 - 4930
(2008/09/17)
-
- Tetrahydropyranylation of alcohols and phenols using the synergistic catalyst system, copper(II) chloride-acetic acid
-
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
-
p. 599 - 602
(2008/02/03)
-
- Efficient and ecofriendly protocol for tetrahydropyranylation/ depyranylation of alcohols in the presence of tin(II) chloride dihydrate
-
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
-
p. 595 - 599
(2007/10/03)
-
- Reaction of tetrahydropyranyl ethers with triethylsilyl trifluoromethanesulfonate-2,4,6-collidine combination: Speculation on the intermediate, efficient deprotection, and application to efficient ring-closing metathesis as a tether
-
The reaction of tetrahydropyranyl (THP) ethers with triethylsilyl trifluoromethanesulfonate (TESOTf)-2,4,6-collidine proceeded via collidinium salt intermediates to give the alcohol and 4-triethylsiloxybutanal in good yields. The structure of the intermediate was confirmed by 1HNMR and FAB-MS studies and by trapping it with EtOH. The reaction was applied for mild, efficient, and highly chemoselective deprotection method of THP ethers. The characteristic feature of the reaction is that the reaction conditions are weakly basic. Then, the reaction can proceed without affecting acid-labile protecting groups. Furthermore, the intermediates from alkenol-THP ether were trapped with other alkenols to give acyclic mixed acetals, which were subjected to efficient ring-closing metathesis by using the tetrahydropyranyl unit as a tether.
- Fujioka, Hiromichi,Okitsu, Takashi,Ohnaka, Takuya,Sawama, Yoshinari,Kubo, Ozora,Okamoto, Kazuhisa,Kita, Yasuyuki
-
p. 636 - 646
(2008/02/09)
-
- Ruthenium(III) acetylacetonate [Ru(acac)3] - An efficient chemoselective catalyst for the tetrahydropyranylation (THP) of alcohols and phenols under solvent-free conditions
-
A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free tetrahydropyranylation of different types of alcohols and phenols at ambient temperature in moderate to excellent yields. Notably, selective monoprotection of diols can be achieved chemoselectively. Furthermore, the catalyst could be recovered and reused if necessary.
- Varala, Ravi,Adapa, Srinivas R.
-
p. 1174 - 1179
(2007/10/03)
-
- Silica-supported perchloric acid (HClO4-SiO2): A versatile catalyst for tetrahydropyranylation, oxathioacetalization and thioacetalization
-
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.
-
p. 2497 - 2502
(2008/02/03)
-
- Efficient trimethylsilylation and tetrahydropyranylation of alcohols in the presence of 1,3-dibromo-5,5-dimethylhydantoin
-
Chemoselective trimethylsilylation and tetrahydropyranylation of benzylic and primary and secondary aliphatic alcohols proceed efficiently in the presence of 1,3-dibromo-5,5-dimethylhydantoin (DBH) under mild and completely heterogeneous reaction conditio
- Shirini, Farhad,Zolfigol, Mohammad Ali,Paktinat, Maryam
-
p. 4252 - 4256
(2008/03/27)
-
- Solvent-free carbon-oxygen bond formation catalysed by CeCl 3·7H2O/NaI: Tetrahydropyranylation of hydroxy groups
-
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
-
p. 1476 - 1482
(2007/10/03)
-
- Efficient method for tetrahydropyranylation of alcohols and phenols and deprotection of THP ethers using H14[NaP5W 30O110] as a Green Catalyst
-
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.
-
p. 3103 - 3107
(2007/10/03)
-
- Mild and efficient tetrahydropyranylation of alcohols and dehydropyranylation of THP ethers catalyzed by ferric perchlorate
-
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
-
p. 2543 - 2545
(2007/10/03)
-
- A mild and efficient method for tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols by BiOClO4.xH 2O (or) BiONO3
-
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
-
p. 2396 - 2398
(2007/10/03)
-
- 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)
-
- A mild and efficient tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols by VCl3
-
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
-
p. 1371 - 1373
(2007/10/03)
-
- Silylation and tetrahydropyranylation of alcohols catalyzed by Al(HSO 4)3
-
Trimethylsilylation and tetrahydropyranylation of alcohols are efficiently catalyzed by Al(HSO4)3. All reactions were performed under mild and completely heterogeneous conditions in good-to-high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh
-
p. 1982 - 1985
(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
-
p. 1120 - 1123
(2007/10/03)
-
- Bronsted acidic ionic liquids: Fast, mild, and efficient catalysts for solvent-free tetrahydropyranylation of alcohols
-
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
-
p. 1939 - 1945
(2007/10/03)
-
- Phosphorus pentoxide as an efficient catalyst for the tetrahydropyranylation of alcohols under solvent-free conditions
-
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
-
p. 2149 - 2152
(2007/10/03)
-
- Chemoselective tetrahydropyranylation of alcohols and phenols using polystyrene supported aluminium chloride as a catalyst
-
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
-
p. 715 - 718
(2007/10/03)
-
- SO3H-functionalized silica for acetalization of carbonyl compounds with methanol and tetrahydropyranylation of alcohols
-
Sulfonic acid group-functionalized amorphous silica acts as a highly effective and reusable catalyst for acetalization of various carbonyl compounds with methanol and tetrahydropyranylation of alcohols.
- Shimizu, Ken-Ichi,Hayashi, Eidai,Hatamachi, Tsuyoshi,Kodama, Tatsuya,Kitayama, Yoshie
-
p. 5135 - 5138
(2007/10/03)
-