- Selective hydrogenation of lignin-derived compounds under mild conditions
-
A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
-
supporting information
p. 3069 - 3073
(2020/06/17)
-
- Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)3: an Efficient One-Pot Benzylation of Alcohols
-
The one-pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)3 as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted benzaldehydes as protecting agents under mild conditions. A plausible mechanism was also proposed. (Figure presented.).
- Pelosi, Azzurra,Lanari, Daniela,Temperini, Andrea,Curini, Massimo,Rosati, Ornelio
-
supporting information
p. 4527 - 4539
(2019/08/26)
-
- Entrapment of THF-Stabilized Iridacyclic IrIII Silylenes from Double H?Si Bond Activation and H2 Elimination
-
The reaction of H3SiR (R=Ph, nBu) with cationic η5-C5Me5- (Cp*) and benzo[h]quinolinyl-based iridacycle [1 b]+ gives rise to new [(IrH)→SiRH2]+ adducts. In the presence of THF these adducts readily undergo elimination of H2 gas at subambient temperature to form THF-stabilized metallacyclic IrIII silylene complexes, which were characterized in situ by NMR spectroscopy, trapped in minute amounts by reactive crystallization, and structurally characterized by XRD. Theoretical investigations (static DFT-D reaction-energy profiling, ETS-NOCV) support the promoting role of THF in the H2 elimination step and the consolidation of the Ir-to-Si interaction in the spontaneous (ΔG+/phenylsilane system are relevant catalytic species in the hydrodefluorination of fluoroalkanes.
- Binh, Dang Ho,Hamdaoui, Mustapha,Fischer-Krauser, Diane,Karmazin, Lydia,Bailly, Corinne,Djukic, Jean-Pierre
-
supporting information
p. 17577 - 17589
(2018/11/23)
-
- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
-
Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
- Bayguzina,Gimaletdinova,Khusnutdinov
-
p. 1148 - 1155
(2018/10/24)
-
- Palladium on Carbon-Catalyzed Benzylic Methoxylation for Synthesis of Mixed Acetals and Orthoesters
-
The palladium on carbon (Pd/C)-catalyzed direct methoxylation of the benzylic positions of linear benzyl and cyclic ether substrates proceeded in the presence of i-Pr2NEt under an oxygen atmosphere to give the corresponding mixed acetals. Cyclic acetal derivatives could also be converted into orthoesters. The present direct methoxylation via a carbon-hydrogen (C?H) functionalization can be accomplished using the easily-removed Pd/C and molecular oxygen as a green oxidant. The obtained mixed acetals were transformed into the corresponding ether products by chemoselective substitution of the methoxy group using a silyltriflate, 2,4,6-collidine, and a nucleophile. The orthoester derivative could also be transformed into the cyclic ketal under similar reaction conditions.
- Yasukawa, Naoki,Kanie, Takafumi,Kuwata, Marina,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
-
supporting information
p. 10974 - 10977
(2017/08/22)
-
- Specific reactivity of 2,4,6-tri-tert-butylanilide anions and its application to benzylation reagent
-
The reaction of methyl iodide with an anilide anion prepared from 2,4,6-tri-tert-butylanilide and NaH in CH3CN gave N-methyl anilide (N-alkylation product) as a major product, while in the reaction of benzyl bromide with the anilide anion in DMF, O-benzyl imidate (O-alkylation product) was obtained with almost complete selectivity. The treatment of O-benzyl imidate with alcohols and carboxylic acids in the presence of trifluoromethane sulfonic acid gave benzyl ethers and benzyl esters, respectively.
- Yamada, Tomoyuki,Tsukagoshi, Shiori,Kitagawa, Osamu
-
p. 317 - 320
(2017/01/03)
-
- Vanadium-Catalyzed Oxidative Debenzylation of O-Benzyl Ethers at ppm Level
-
An advantageous methodology for the oxidative debenzylation of ethers has been developed. Very low amounts of a catalyst system based on vanadyl acetylacetonate and a triazole type pincer ligand allow the selective oxidative cleavage of a number of O-benzyl ethers in the presence of oxygen as the sole oxidant. The methodology tolerates a number of functional groups such as halo-, alkoxy-, or trifluoromethylarenes, alkyne, alkene, ether, and acetal units. Large-scale deprotections can be also carried out by the optimized procedure, which is amenable to enantioenriched reactants as well. (Figure presented.).
- Urgoitia, Garazi,SanMartin, Raul,Herrero, María Teresa,Domínguez, Esther
-
supporting information
p. 3307 - 3312
(2016/10/21)
-
- A gold catalytic the method for synthesizing calls the ether
-
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.
- -
-
Paragraph 0029-0032; 0034; 0036
(2017/02/28)
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- Visible-light-promoted conversion of alkyl benzyl ether to alkyl ester or alcohol via O-α-sp3 C-H cleavage
-
A mild and high-yielding visible-light-promoted conversion of alkyl benzyl ethers to the alkyl esters or alkyl alcohols was developed. Mechanistic studies provided evidence for a radical chain reaction involving the homolytic cleavage of O-α-sp3 C-H bonds in the substrate as one of the propagation steps. We propose that α-bromoethers are key intermediates in the transformation.
- Lu, Ping,Hou, Tianyuan,Gu, Xiangyong,Li, Pixu
-
supporting information
p. 1954 - 1957
(2015/04/27)
-
- Gold(I)-catalyzed synthesis of unsymmetrical ethers using alcohols as alkylating reagents
-
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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- Synthesis of ethers from carbonyl compounds by reductive etherification catalyzed by iron(III) and silyl chloride
-
A simple iron- and silyl chloride catalyzed method for the preparation of symmetrical and nonsymmetrical ethers is presented. Various aldehydes and ketones were reductively etherified by using triethylsilane as a reducing agent in the presence of 2 mol% of iron(III) oxo acetate and 8 mol% of chloro(trimethyl)silane. The reactions can be carried out at ambient temperatures and pressures with ethyl acetate as the solvent.
- Savela, Risto,Leino, Reko
-
p. 1749 - 1760
(2015/06/16)
-
- Selective aliphatic carbon-hydrogen bond activation of protected alcohol substrates by cytochrome P450 enzymes
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Protected cyclohexanol and cyclohex-2-enol substrates, containing benzyl ether and benzoate ester moieties, were designed to fit into the active site of the Tyr96Ala mutant of cytochrome P450cam. The protected cyclohexanol substrates were efficiently and selectively hydroxylated by the mutant enzyme at the trans C-H bond of C-4 on the cyclohexyl ring. The selectivity of oxidation of the benzoate ester protected cyclohexanol could be altered by making alternative amino acid substitutions in the P450cam active site. The addition of the double bond in the cyclohexyl ring of the benzoate ester protected cyclohex-2-enol has a debilitative effect on the activity of the Tyr96Ala mutant with this substrate. However, the Phe87Ala/Tyr96Phe double mutant, which introduces space at a different location in the active site than the Tyr96Ala mutant, was able to efficiently hydroxylate the C-H bonds of 1-cyclohex-2-enyl benzoate at the allylic C-4 position. Mutations at Phe87 improved the selectivity of the oxidation of 1-phenyl-1-cyclohexylethylene to trans-4-phenyl-ethenylcyclohexanol (92%) when compared to single mutants at Tyr96 of P450cam. the Partner Organisations 2014.
- Bell, Stephen G.,Spence, Justin T. J.,Liu, Shenglan,George, Jonathan H.,Wong, Luet-Lok
-
supporting information
p. 2479 - 2488
(2014/04/03)
-
- Benzylation of arenes with benzyl ethers promoted by the in situ prepared superacid BF3-H2O
-
An efficient and environmentally friendly benzylation of arenes with benzyl ethers as benzyl donors using BF3-Et2O to generate in situ the superacid BF3-H2O as an efficient promotor has been described. A wide variety of functional groups have been investigated and found to be compatible to give the desired diarylmethanes in yields of up to 99%. The crucial role of the moisture content in this transformation has been demonstrated by detailed investigations. This journal is the Partner Organisations 2014.
- Li, Yu,Xiong, Yan,Li, Xueming,Ling, Xuege,Huang, Ruofeng,Zhang, Xiaohui,Yang, Jianchun
-
supporting information
p. 2976 - 2981
(2014/06/10)
-
- Benzylation of hydroxy groups with tertiary amine as a base
-
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
-
experimental part
p. 370 - 375
(2012/01/14)
-
- A novel method for synthesis of benzyl alkyl ethers using Vanadium-based metal complex catalysts
-
A novel method has been developed for the synthesis of benzyl alkyl ethers in 25-85% yields via the reaction of toluene with alcohols in a CCl4 medium catalyzed by Et3N-activated VO(acac)2.
- Khusnutdinov,Bayguzina,Gallyamova,Dzhemilev
-
p. 261 - 266
(2012/10/29)
-
- New method for the synthesis of benzyl alkyl ethers mediated by FeSO 4
-
The synthesis of benzyl alkyl ethers from benzyl bromides and alcohols using FeSO4 as a recoverable and reusable mediator has been described without use of base and cosolvent under mild conditions.
- Joshi, Girdhar,Adimurthy, Subbarayappa
-
experimental part
p. 720 - 728
(2011/03/22)
-
- Expanded substrate scope and improved reactivity of ether-forming cross-coupling reactions of organotrifluoroborates and acetals
-
Mixed acetals and organotrifluoroborates undergo BF3· OEt2-promoted cross-couplings to give dialkyl ethers under simple, mild conditions. A survey of reaction partners identified a hydroxamate leaving group that improves the regioselectivity and product yield in the BF 3·OEt2-promoted coupling reaction of mixed acetals and potassium alkynyl-, alkenyl-, aryl- and heteroaryltrifluoroborates to access substituted dialkyl ethers. This leaving group enables the reaction to proceed rapidly under mild conditions (0 °C, 5-60 min) and permits reactions with electron-deficient potassium aryltrifluoroborates that are less reactive with other acetal substrates. A study of the reaction mechanism and characterization of key intermediates by NMR spectroscopy and X-ray crystallography identified a role for the hydroxamate moiety as a reversible leaving group that serves to stabilize the key oxocarbenium intermediate and the need for a slight excess of organodifluoroborane to serve as a catalyst. A secondary role for the boron nucleophile as an activating ligand was also considered. These studies provide the basis for a general class of reagents that lead to dialkyl ethers by a simple, predictable cross-coupling reaction.
- Vo, Cam-Van T.,Mitchell, T. Andrew,Bode, Jeffrey W.
-
supporting information; experimental part
p. 14082 - 14089
(2011/10/12)
-
- Chlorine borrowing: An efficient method for an easier use of alcohols as alkylation agents
-
Chlorine functionalised tin dioxide nanoparticles proved able to partially convert alcohols into the corresponding chlorides, which act as alkylation agents with an increased electrophilicity, as evidenced on ether formation and Friedel-Crafts reactions.
- Makowski, Philippe,Rothe, Regina,Thomas, Arne,Niederberger, Markus,Goettmann, Frederic
-
scheme or table
p. 34 - 37
(2010/04/22)
-
- Gold-catalyzed substitution reaction with ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
-
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
-
experimental part
p. 1774 - 1784
(2009/06/20)
-
- [IrCl2Cp*(NHC)] complexes as highly versatile efficient catalysts for the cross-coupling of alcohols and amines
-
A comparative study on the catalytic activity of a series of [IrCl 2Cp*(NHC)] complexes in several C-O and C-N coupling processes implying hydrogen-borrowing mechanisms has been performed. The compound [IrCl2Cp*(InBu)] (Cp* = pentamethyl cyclopentadiene; InBu = 1,3-di-n-butylimidazolylidene) showed to be highly effective in the cross-coupling reactions of amines and alcohols, providing high yields in the production of unsymmetrical ethers and N-alkylated amines. A remarkable feature is that the processes were carried out in the absence of base, phosphine, or any other external additive. A comparative study with other known catalysts, such as Shvo's catalyst, is also reported.
- Prades, Amparo,Corberan, Rosa,Poyatos, Macarena,Peris, Eduardo
-
scheme or table
p. 11474 - 11479
(2009/12/03)
-
- Gold-catalyzed etherification and friedel - Crafts alkylation using ortho-alkynylbenzoic acid alkyl ester as an efficient alkylating agent
-
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
-
p. 4299 - 4302
(2008/02/12)
-
- Cesium fluoride-Celite: A solid base for efficient syntheses of aromatic esters and ethers
-
Coupling reactions of a number of aromatic and heteroaromatic phenols with alkyl, acyl or benzoyl halides in acetonitrile with cesium fluoride-Celite are described, demonstrating that this reagent provides an efficient, convenient and practical method for the syntheses of aromatic esters and ethers.
- Shah, Syed Tasadaque Ali,Khan, Khalid Mohammed,Hussain, Hidayat,Anwar, Muhammad Usman,Fecker, Miriam,Voelter, Wolfgang
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p. 6652 - 6656
(2007/10/03)
-
- An efficient method for the ether forming reaction between alkyl diphenylphosphinate and alkoxytrimethylsilane by the promotion of trimethylsilyl triflate
-
The trimethylsilyl triflate promoted reactions of alkyl diphenylphosphinates with alkoxytrimethylsilanes in chloroform, 1,2-dichloroethane or 1,2-dichloropropane, proceeded smoothly to give the corresponding ethers in good yields.
- Kobashi, Yohei,Minowa, Tomofumi,Mukaiyama, Teruaki
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p. 1362 - 1363
(2007/10/03)
-
- Benzylation of alcohols by using bis[acetylacetonato]copper as catalyst
-
Selective O-benzylation of primary hydroxy compounds has been achieved in the presence of bis[acetylacetonato]copper with benzyl chloride. We showed that bis[acetylacetonato]copper was very efficient in promoting the benzylation of primary aliphatic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups selectively.
- Sirkecioglu, Okan,Karliga, Bekir,Talinli, Naciye
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p. 8483 - 8485
(2007/10/03)
-
- Lewis acid-catalyzed reductive etherification of carbonyl compounds with alkoxyhydrosilanes
-
The TMSI-catalyzed reaction of aldehydes and ketones with alkoxydimethylsilanes gave unsymmetrical ethers in good to high yields. This reductive etherification is superior to the conventional method using two kinds of silicon reagents in terms of atom eff
- Miura, Katsukiyo,Ootsuka, Kazunori,Suda, Shuntaro,Nishikori, Hisashi,Hosomi, Akira
-
p. 313 - 315
(2007/10/03)
-
- N-nitroso-N,O-dialkylhydroxylamines: Preparation, structure, and mechanism of the hydronium ion catalysed solvolytic nitrous oxide extrusion reaction
-
Eleven N-nitroso-N,O-dialkylhydroxylamines, RN(NO)OR′, have been prepared and the mechanisms of their hydronium ion catalysed solvolyses in aqueous solution which liberate nitrous oxide have been investigated. All reactions are first-order in substrate and first-order in hydronium ion, and the second-order rate constants at 25°C vary over a range of less than 140 in spite of considerable variation in substrate structure (R ranges from methyl to 4-methoxybenzyl to 2-adamantyl, for example) and changes in solvent composition (water with up to 50% methanol or 66% acetonitrile). Enthalpies and entropies of activation are qualitatively similar throughout the range (ΔH?= 72-93 kJ mol-1 and ΔS? = -19 to -57 J K-1 mol-1) which, with the product analyses, are accommodated by a mechanism involving pre-equilibrium protonation of the substrates followed by rate-limiting dissociation to give RN2O+ and HOR′. The oxodiazonium ion intermediate, RN2O+, then dissociates further to give the carbenium ion intermediate, R+, or suffers direct nucleophilic displacement of N2O by solvent (the external nucleophile) or by R′OH (the internal nucleophile liberated in the initial fragmentation). The carbenium ion, R+ (if formed), suffers nucleophilic capture either by solvent or by R′OH. When acetonitrile is the co-solvent (rather than methanol) for the N-(2-adamantyl) substrate 3g, the product of the Ritter reaction, 2-acetamidoadamantane, is detected. These nitrous oxide liberating reactions are compared with the nitric oxide liberating reactions of related N-nitrosohydroxylamines, and the origin of the difference between them is identified. The N(1)-nitroso group in the N,O-dibenzyl compound 3c is shown by X-ray crystallography to be essentially coplanar with the C and O atoms also bonded to N(1).
- Bhat, J. Ishwara,Clegg, William,Maskill, Howard,Elsegood, Mark R.J.,Menneer, Iain D.,Miatt, Peter C.
-
p. 1435 - 1446
(2007/10/03)
-
- BiBr3, an efficient catalyst for the benzylation of alcohols: 2-Phenyl- 2-propyl, a new benzyl-type protecting group
-
The benzylation of aliphatic alcohols with various benzylic alcohols has been achieved in the presence of BiBr3 under mild conditions. 2- Phenylpropan-2-ol proved to be the most efficient and can be considered as a novel protecting group. (C) 2000 Elsevier Science Ltd.
- Boyer, Bernard,Keramane, El-Mehdi,Roque, Jean-Pierre,Pavia, André A.
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p. 2891 - 2894
(2007/10/03)
-
- Novel reactions of ethylene acetals with silyl-substituted nucleophiles. A mild and efficient procedure for the synthesis of homoallyl alkyl ethers and unsymmetrical dialkyl ethers
-
Efficient one-pot synthesis of homoallyl alkyl ethers and dialkyl ethers was performed by the allylation and reduction of ethylene acetals with allyltrimethylsilane and t-butyldimethylsilane, respectively, in the presence of alkoxytrimethylsilane.
- Suzuki, Takeshi,Oriyama, Takeshi
-
p. 1263 - 1269
(2007/10/03)
-
- Bismuth Bromide-Catalyzed reductive coupling of carbonyl compounds and its application to the synthesis of novel crownophanes
-
The reductive homocoupling of carbonyl compounds and heterocoupling of a carbonyl compound with an alkoxysilane were both effected smoothly with triethylsilane in the presence of a catalytic amount of bismuth bromide (1-3 mol%) under mild conditions. This ether-forming reaction was successfully applied to the single-step preparation of novel crownophanes with olefinic or acetylenic linkages.
- Komatsu, Naoki,Ishida, Jun-Ya,Suzuki, Hitomi
-
p. 7219 - 7222
(2007/10/03)
-
- Hypervalent (tert-butylperoxy)iodanes generate iodine-centered radicals at room temperature in solution: Oxidation and deprotection of benzyl and allyl ethers, and evidence for generation of α-oxy carbon radicals
-
1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C-H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C-H bonds) and/or polar effects (α-oxy C-H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p-s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the σ+ constants of substituents afforded the reaction constant ρ+ = -0.30. The large value of the isotope effect obtained for the oxidation of benzyl n-butyl ether 2d (k(H)/k(D) = 12-14) indicates that the rate-determining step of the reactions probably involves a high degree of benzylic C-H bond breaking. The effects of molecular dioxygen were examined, and the mechanism involving the intermediacy of the tert-butylperoxy acetal 5 and/or the hydroperoxy acetal 32 is proposed. Particularly noteworthy is the finding that (tert-butylperoxy)iodane 1a can generate the tert-butylperoxy radical and the iodine-centered radical 33a, even at room temperature in solution, via homolytic bond cleavage of the hypervalent iodine(III)-peroxy bond.
- Ochiai, Masahito,Ito, Takao,Takahashi, Hideo,Nakanishi, Akinobu,Toyonari, Mika,Sueda, Takuya,Goto, Satoru,Shiro, Motoo
-
p. 7716 - 7730
(2007/10/03)
-
- Efficient reductive etherification of carbonyl compounds with alkoxytrimethylsilanes
-
An efficient TMSOTf catalyzed ether synthesis from carbonyl compounds and alkoxytrimethylsilanes via triethylsilane-reduction is described.
- Hatakeyama, Susumi,Mori, Hisato,Kitano, Kaori,Yamada, Hidetoshi,Nishizawa, Mugio
-
p. 4367 - 4370
(2007/10/02)
-
- A Discriminating Protecting Group Strategy for Alcohols and Amines
-
The protection of alcohols and amines as O- and N-benzyl derivatives has long played a central role in organic synthesis.For case where the conventional method of benzylation under strongly base conditions is not applicable, we now describe an alternate method using phenyldiazomethane that proceeds under near-neutral conditions with HBF4 as a catalyst.O-Benzylation occurs at -40 deg C and works well on primary, secondary, and tertiary alcohols.The techique is compatible with ester, acetal, and relative halide functiolatities.Under the same conditions PhCHN2 also N-benzylates primary and secondary amines, albait more slowly.However S-benzylation is only marginally successful.As a consequence aminoalcohols like 2-hydroxymethylpiperidine can be O-benzylayed cleanly and in good yield.Thus HBF4-mediated benzylations using PhCHN2 achieve a kinetic selectivity not customarily possible in the standard Williamson ether synthesis.Preliminary experiments with other, substituted phenyldiazomethanes indicate the method can be extended to the production of substituted benzyl ethers and amines.
- Liotta, Louis J.,Ganem, Bruce
-
p. 215 - 222
(2007/10/02)
-
- Characteristic Reduction of Ketones by Bu3SnH-Bu4NX System
-
Various ketones were reduced cleanly by Bu3SnH-Bu4NX (X=halogen) combined systems.The reaction proceeds effectively under mild conditions.Chemoselective reduction was performed in bifunctional compounds, and marked diastereoselective reduction was noted for α-methoxy propiophenone.
- Shibata, Ikuya,Yoshida, Tomoyuki,Baba, Akio,Matsuda, Haruo
-
p. 307 - 310
(2007/10/02)
-
- SELECTIVE BENZYLATION OF ALCOHOLS AND AMINES UNDER MILD CONDITIONS
-
A new synthesis of benzyl ethers and N-benzylamines is described under nonbasic conditions using the fluoboric catalyzed reaction of phenyldiazomethane
- Liotta, Louis J.,Ganem, Bruce
-
p. 4759 - 4762
(2007/10/02)
-
- General Ether Synthesis under Mild Acid-Free Conditions. Trimethylsilyl Iodide Catalyzed Reductive Coupling of Carbonyl Compounds with Trialkylsilanes to Symmetrical Ethers and Reductive Condensation with Alkoxysilanes to Unsymmetrical Ethers
-
Facile synthesis of symmetrical ethers is achieved by either trimethylsilyl triflate or trimethylsilyl iodide catalyzed reductive coupling of carbonyl compounds (aldehydes and ketones) with trialkylsilanes.The method was also extended to the trimethylsilyl iodide catalyzed preparation of unsymmetrical ethers by reductive condensation (of carbonyl compounds) with alkoxysilanes.The scope and limitations of the reactions are discussed with emphasis on diastereoselectivity.
- Sassaman, Mark B.,Kotian, Kirtivan D.,Prakash, G. K. Surya,Olah, George A.
-
p. 4314 - 4319
(2007/10/02)
-
- Interhalogen-Catalyzed Cleavages of Ethers and Esters with Trimethylsilyl Bromide or Chloride
-
The cleavages of various dialkyl ethers, trimethylsilyl alkyl ethers, and alkyl esters by trimethylsilyl bromide are strongly catalyzed by iodine monobromide.This catalyzed cleavage procedure using iodine monobromide makes possible synthetic applications for trimethylsilyl bromide which were previously ruled out by problems with its low reactivity.Cleavages of benzylic and tertiary alkyl ethers and esters by trimethylsilyl chloride are feasible when catalyzed by iodine monochloride.However, other systems are essentially unreactive toward trimethylsilyl chloride even in the presence of iodine monochloride.
- Friedrich, Edwin C.,DeLucca, George
-
p. 1678 - 1682
(2007/10/02)
-