- Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis
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Kinetic analysis was used as a tool for rational optimization of a catalytic, direct substitution of alcohols to enable the selective formation of unsymmetrical ethers, thioethers, and Friedel-Crafts alkylation products using a moisture-tolerant and commercially available zirconium complex (2 to 8 mol%). Operating in air and in the absence of dehydration techniques, the protocol furnished a variety of products in high yields, including glycosylated alcohols and sterically hindered ethers. In addition, the kinetic studies provided mechanistic insight into the network of parallel transformations that take place in the reaction, and helped to elucidate the nature of the operating catalyst.
- Camaj, David,Carlsson, Robin,Dalla-Santa, Oscar,Lill, Malin,Lundberg, Helena,Margarita, Cristiana,Ramstr?m, Anja,Tu?on, Hernando,Villo, Piret
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p. 7420 - 7430
(2021/11/23)
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- Direct and efficient synthesis of unsymmetrical ethers from alcohols catalyzed by Fe(HSO4)3 under solvent-free conditions
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Highly efficient Fe(HSO4)3 catalyzed etherification of primary, secondary and tertiary benzylic alcohols with primary and secondary aliphatic alcohols is reported. The reaction affords unsymmetrical benzyl ethers in good to excellent yields under solvent-free conditions.
- Moghadam, Bashir Nazari,Akhlaghinia, Batool,Rezazadeh, Soodabeh
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p. 1487 - 1501
(2016/04/26)
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- A gold catalytic the method for synthesizing calls the ether
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The invention provides a synthetic method of asymmetrical ether in the field of organic synthesis. The general equation of reaction is defined in the specification. In the equation, R-OH is benzyl alcohol, p-methoxy benzyl alcohol, tert-butyl alcohol, diphenyl carbinol or triphenylmethanol; and R'OH is common alkyl alcohol or a compound containing hydroxyl groups. A gold catalyst required by the reaction is Ph3PAuCl, Ph3PAuNTf2, HAuCl4, NaAuCl4, Ph3PAuOTf, Ph3PAuSbF6, IPrAuCl or nano-gold. A medium required by the reaction is solvent-free, and is toluene, mesitylene, 1,2-dichloroethane, tetrahydrofuran, acetonitrile or acetone. The reaction is implemented by heating through a microwave reactor. The method has advantages as follows: raw materials are easily available; operation is simple; the range of application is wide; atom economy is good; and the reaction is green.
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Paragraph 0042-0045
(2017/02/28)
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- METHOD OF PRODUCING VINYLBENZYL(FLUOROALKYL) ETHER
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PROBLEM TO BE SOLVED: To provide a method of producing a vinylbenzyl(fluoroalkyl) ether industrially at low costs. SOLUTION: A method of producing a vinylbenzyl(fluoroalkyl) ether of formula (1) (in the formula, Rf is a fluoroalkyl group, and n is an integer of 1-3) comprises reacting a fluoroalkyl alcohol of formula (2) (in the formula, Rf is a fluoroalkyl group, and n is an integer of 1-3) with chloromethylstyrene in a solvent selected from tertiary alcohols, nitrogen-containing organic solvents and sulfur-containing organic solvents in the presence of a solid alkali. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0012
(2016/11/14)
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- Gold(I)-catalyzed synthesis of unsymmetrical ethers using alcohols as alkylating reagents
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A microwave-irradiated alcohol-protecting strategy based on gold catalysis utilizing benzyl alcohol, tert-butyl alcohol and triphenylmethanol as alkylating reagents has been developed. This protecting strategy has wide functional group tolerance with satisfactory yields for the majority of the selected alcohols. The mechanism of this transformation was probed with oxygen-18 isotope labelled alcohols assisted by GC-MS techniques and chemical kinetic experiments. This strategy provides an efficient, straightforward and alternative approach to the preparation of benzyl, tert-butyl and trityl ethers in organic synthesis.
- Liu, Yongxiang,Wang, Xiaoyu,Wang, Yanshi,Du, Chuan,Shi, Hui,Jin, Shengfei,Jiang, Chongguo,Xiao, Jianyong,Cheng, Maosheng
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p. 1029 - 1036
(2015/03/30)
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- Step-economy etherification of acylated alcohols
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An efficient and convenient protocol has been developed for ether bond formation in mild conditions. A mixture of primary/secondary ester and allylic/benzylic halide in tetrahydrofuran was treated with KOtBu at room temperature to give ether in high yield. This step economic method enabled direct alkylation of the acyl group masked O-nucleophiles. Application of this method in carbohydrate synthesis was feasible and chemo-selectivity can be achieved.
- Xu, Hua-Dong,Xu, Ke,Zheng, Qing,He, Wei-Jie,Shen, Mei-Hua,Hu, Wen-Hao
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supporting information
p. 6836 - 6838
(2015/01/09)
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- A convenient approach for the deprotection and scavenging of the PMB group using POCl3
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A convenient and high yielding approach for the deprotection and scavenging of the p-methoxybenzyl (PMB) group in PMB ethers and PMB esters was developed using POCl3 as the reagent. 4-Methoxybenzyl chloride, a starting material used for the preparation of PMB ethers and esters was regenerated in the deprotection step. This mild and selective procedure tolerates several acid sensitive functional groups. The Royal Society of Chemistry 2013.
- Ilangovan, Andivelu,Saravanakumar, Shanmugasundar,Malayappasamy, Subramani,Manickam, Govindaswamy
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p. 14814 - 14828
(2013/09/02)
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- Benzylation of hydroxy groups with tertiary amine as a base
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The benzylation of hydroxy groups in the presence of tertiary amines is described. A mixture of an alcohol and a benzyl halide afforded the corresponding benzyl ether in good to excellent yields in the presence of diisopropylethylamine. The importance of solventless conditions was observed. The reaction showed high tolerance to many functional groups including benzoate, even at a reaction temperature of 150 °C. Sodium iodide was found to be an efficient catalyst to accelerate the reaction.
- Gathirwa, Jeremiah W.,Maki, Toshihide
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experimental part
p. 370 - 375
(2012/01/14)
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- Suzuki coupling of potassium cyclopropyl- and alkoxymethyltrifluoroborates with benzyl chlorides
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Efficient Csp3-Csp3 Suzuki couplings have been developed with both potassium cyclopropyl- and alkoxymethyltrifluoroborates. Moderate to good yields have been achieved in the cross-coupling of potassium cyclopropyltrifluoroborate with benzyl chlorides possessing electron-donating or electron-withdrawing substituents. Benzyl chloride was also successfully cross-coupled to potassium alkoxymethyltrifluoroborates derived from primary, secondary, and tertiary alcohols.
- Colombel, Virginie,Rombouts, Frederik,Oehlrich, Daniel,Molander, Gary A.
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experimental part
p. 2966 - 2970
(2012/06/01)
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- A mild method for the protection of alcohols using a para-methoxybenzylthio tetrazole (PMB-ST) under dual acid-base activation
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With a view to expand the repertoire of chemoselective methods applicable to sensitive and multifunctional substrates, the p-methoxybenzylation of alcohols under essentially neutral conditions is reported. This was achieved by the silver triflate (AgOTf) activation of 5-(p-methoxybenzylthio)-1-phenyl-1H-tetrazole (PMB-ST) in the presence of 2,6-di-tert-butyl-4-methylpyridine (DTBMP).
- Kotturi, Santosh R.,Tan, Jason S.,Lear, Martin J.
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supporting information; experimental part
p. 5267 - 5269
(2009/12/24)
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- Gold-catalyzed substitution reaction with ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
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ortho-Alkynylbenzoic acid alkyl esters behave as alkylating agents in combination with gold catalysts. The reaction with alcohols occurs smoothly in the presence of catalytic amounts of Ph3PAuCl and AgOTf under mild conditions to produce the corresponding ether products in high yields. The protocol is also useful for Friedel-Crafts alkylation and N-alkylation of sulfonamides. The reaction likely proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack of nucleophiles, such as alcohols, aromatic compounds, and sulfonamides.
- Aikawa, Haruo,Tago, Sakie,Umetsu, Kazuteru,Haginiwa, Naomichi,Asao, Naoki
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experimental part
p. 1774 - 1784
(2009/06/20)
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- Facile cleavage of ethers in ionic liquid
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Various alkyl ethers were efficiently cleaved by treating them with pyridinium halides in ionic liquid, and the desired products were obtained in excellent yields.
- Cheng, Lili,Aw, Carlin,Ong, Siew Siang,Lu, Yixin
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supporting information; experimental part
p. 2008 - 2010
(2009/08/14)
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- Gold-catalyzed etherification and friedel - Crafts alkylation using ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
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A gold-catalyzed alkylation of alcohols and aromatic compounds is described. The reaction of ortho-alkynylbenzoic acid alkyl esters with alcohols or aromatic compounds occurs in the presence of catalytic amounts of Ph 3PAuCl and AgOTf under mild conditions to produce corresponding ethers or Friedel-Crafts alkylation products in good to high yields. The reaction likely proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack of alcohols or aromatic compounds.
- Asao, Naoki,Aikawa, Haruo,Tago, Sakie,Umetsu, Kazuteru
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p. 4299 - 4302
(2008/02/12)
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- Efficient methods for the preparation of alkyl-aryl and symmetrical or unsymmetrical dialkyl ethers between alcohols and phenols or two alcohols by oxidation-reduction condensation
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Oxidation-reduction condensation via alkoxydiphenylphosphines (diphenylphosphinite esters) (1), generated in situ from chlorodiphenylphosphine (2) and alcohols, 2,6-dimethyl-1,4-benzoquinone (3), and phenols proceeds smoothly to afford alkyl-aryl ethers in good to high yields under neutral conditions. In a similar fashion, a new and efficient method for the preparation of symmetrical or unsymmetrical dialkyl ethers in good to high yields is established via tetrafluoro-1,4-benzoquinone (fluoranil) (4), alcohols, and 1 formed in situ from nBuLi-treated alcohols and 2. This method is applicable also to the etherification of chiral secondary or tertiary alcohols with retention or inversion of configurations. The inverted ethers are afforded by treating chiral alkoxydiphenylphosphines and achiral alcohols, while the reaction of achiral alkoxydiphenylphosphines and chiral alcohols forms retained ethers.
- Shintou, Taichi,Mukaiyama, Teruaki
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p. 7359 - 7367
(2007/10/03)
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- Zirconium(IV) chloride catalyzed new and efficient protocol for the selective cleavage of p-methoxybenzyl ethers
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A highly selective and efficient method for the unmasking of p-methoxybenzyl (PMB) ethers and esters has been developed by use of 20 mol % of zirconium(IV) chloride as Lewis acid in acetonitrile. The present method is very fast, and the conditions are tolerable to a variety of acid/ base-sensitive protecting groups and substrates such as carbohydrates, terpenes, and amino acids. The products are obtained in good to high yields.
- Madhava Sharma, Gangavaram V.,Reddy, Ch. Govardhan,Krishna, Palakodety Radha
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p. 4574 - 4575
(2007/10/03)
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- A Convenient Method for the Preparation of Symmetrical or Unsymmetrical Ethers by the Coupling of Two Alcohols via a New Type of Oxidation-reduction Condensation Using Tetrafluoro-1,4-benzoquinone
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A new type of oxidation-reduction condensation by using tetrafluoro-1,4-benzoquinone (fluoranil), alcohols and alkoxydiphenylphosphines, in situ formed from nBuLi-treated alcohols and chlorodiphenylphosphine, proceeded smoothly to afford the corresponding symmetrical or unsymmetrical ethers in good to high yields.
- Shintou, Taichi,Mukaiyama, Teruaki
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p. 984 - 985
(2007/10/03)
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- An efficient method for the p-methoxybenzylation of hydroxy groups with 2-(4-methoxybenzyloxy)-3-nitropyridine
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2-(4-Methoxybenzyloxy)-3-nitropyridine (PMBONPy), easily prepared from 2-chloro-3-nitropyridine and p-methoxybenzyl (PMB) alcohol, reacts with various types of hydroxy groups in the presence of a catalytic amount of trimethylsilyl triflate (Me3SiOTf) to give the corresponding PMB ethers in high yields under mild conditions.
- Nakano, Masakazu,Kikuchi, Wataru,Matsuo, Jun-Ichi,Mukaiyama, Teruaki
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p. 424 - 425
(2007/10/03)
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- A new high yield preparation of benzyl phenethyl ethers by phase transfer catalysis
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A phase transfer method to prepare benzyl phenethyl ethers from electron-rich benzyl halides and 2-phenylethanols supporting electron- withdrawing groups is described. The yields are excellent, in contrast to the very low ones previously reported for the same kind of compounds prepared by other ways.
- Lopez-Calahorra, Francisco,Ballart, Berta,Hombrados, Felix,Marti, Josep
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p. 795 - 799
(2007/10/03)
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- Lewis Acid-Catalyzed Deprotection of p-Methoxybenzyl Ether
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The p-methoxybenzyl protecting group was readily removed from alcohols and phenols using catalytic amounts of AlCl3 or SnCl2 · 2H2O in the presence of EtSH at room temperature. Under these mild conditions other protecting groups such as methyl and benzyl ethers, p-nitrobenzoyl esters, TBDPS ethers and isopropylidene acetal were unchanged.
- Bouzide, Abderrahim,Sauvé, Gilles
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p. 1153 - 1154
(2007/10/03)
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- MPM (4-METHOXYBENZYL) PROTECTION OF HYDROXY FUNCTIONS UNDER MILD ACIDIC CONDITIONS
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In order to establish a mild protection method for hydroxy functions with a MPM (4-methoxybenzyl) group, various types of hydroxy compounds were treated with MPM trichloroacetimidate in the presence of an acid catalyst.A catalytic amount (0.3 mol percent)
- Nakajima, Noriyuki,Horita, Kiyoshi,Abe, Reiko,Yonemitsu, Osamu
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p. 4139 - 4142
(2007/10/02)
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