- Preparation and application of 5-bromoquinazoline derivative
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The invention discloses a 5-bromoquinazoline derivative shown in the corresponding formula. A synthesis method of the 5-bromoquinazoline derivative compound (I) comprises the following steps: weighing1.18 g of 5-bromoisatin, 2.5503g of ammonium formate an
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Paragraph 0032-0034
(2021/02/16)
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- METAL-IODIDE CATALYTIC SYSTEM FOR DIRECT ETHERIFICATION FROM ALDEHYDES AND/OR KETONES
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A process for etherification of aldehydes and/or ketones in the presence of a catalyst and an iodine source.
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Page/Page column 13; 14
(2020/01/24)
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- Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)3: an Efficient One-Pot Benzylation of Alcohols
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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
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supporting information
p. 4527 - 4539
(2019/08/26)
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- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
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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
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p. 1148 - 1155
(2018/10/24)
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- Palladium on Carbon-Catalyzed Benzylic Methoxylation for Synthesis of Mixed Acetals and Orthoesters
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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
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supporting information
p. 10974 - 10977
(2017/08/22)
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- Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
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Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
- Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
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supporting information
p. 5217 - 5221
(2017/04/27)
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- A novel method for synthesis of benzyl alkyl ethers using Vanadium-based metal complex catalysts
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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
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p. 261 - 266
(2012/10/29)
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- New method for the synthesis of benzyl alkyl ethers mediated by FeSO 4
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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
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experimental part
p. 720 - 728
(2011/03/22)
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- Triflic acid catalyzed reductive coupling reactions of carbonyl compounds with O-, S-, and N-nucleophiles
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Highly efficient metal-free reductive coupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1-5 mol %) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the first time, the influence of additional functionalization has been studied. Furthermore, the formation of thioethers from ketones (by addition of unmodified thiols) and of sulfonamides from either aldehydes or ketones has been achieved under catalytic conditions.
- Gellert, Beate A.,Kahlcke, Nils,Feurer, Markus,Roth, Stefanie
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supporting information; experimental part
p. 12203 - 12209
(2011/11/07)
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- [IrCl2Cp*(NHC)] complexes as highly versatile efficient catalysts for the cross-coupling of alcohols and amines
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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
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scheme or table
p. 11474 - 11479
(2009/12/03)
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- Efficient preparation of new fluorinated lithium and ammonium sulfonimides
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(Chemical Equation Presented) An efficient preparation of new fluorinated lithium and ammonium sulfonimides, from the corresponding sulfonyl fluorides, is reported. These sulfonyl fluorides are reacted with benzylamine, then triflated. Due to the high lea
- Toulgoat, Fabien,Langlois, Bernard R.,Medebielle, Maurice,Sanchez, Jean-Yves
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p. 5613 - 5616
(2008/12/21)
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- New concept for the preparation of potassium sodides: The use of hexane as a non-polar solvent
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NaK alloy in contact with 15-crown-5 hexane solution became potassium sodide K+(15-crown-5)2Na-. After the evaporation of hexane the crystalline solid product was analyzed by X-ray diffraction and the lattice parameters were calculated. The potassium sodide thus obtained could be easily dissolved in tetrahydrofuran. A deep blue solution containing sodium anions and complexed potassium cations was formed with a very low concentration of solvated electrons, i.e. of the order of 10-7M. Potassium anions were not detected in this case. A new crystalline potassium sodide K+(DCH-24-crown-8)2Na- was obtained using NaK alloy and dicyclohexano-24-crown-8 hexane solution.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Morejko-Buz, Barbara,Winiarski, Antoni
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p. 2147 - 2150
(2007/10/03)
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- Etherification of alkoxydialkylsilanes with carbonyl compounds
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A novel method for preparing ethers from alkoxydialkylsilanes and carbonyl compounds through reductive etherification is described. The salient feature in this method is the utilization of internal hydrogen as the hydride source for reducing the oxonium intermediate generated by using the Cl(R)2SiBr[BiBr3/Cl(R)2SiH] catalytic system.
- Jiang, Xinglong,Bajwa, Joginder S,Slade, Joel,Prasad, Kapa,Repi?, Oljan,Blacklock, Thomas J
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p. 9225 - 9227
(2007/10/03)
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- Study of the stability of carbocations by chlorosulfonyl isocyanate reaction with ethers
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The stability order of various alkyl, allyl, and benzyl carbocations was investigated using the novel technique for comparing the stability of carbocations in solution developed by using a simple CSI reaction with various ethers. The p-methoxycinnamyl carbocation was the most stable in our reaction system and the next stable carbocation was the p-methoxybenzyl carbocation. The stability of the other carbocations decreased with methacryl, t-butyl, cinnamyl, acryl, benzyl, 2° and allyl carbocations in that order.
- Kim, Ji Duck,Han, Gyoonhee,Jeong, Lak Shin,Park, Hyun-Ju,Zee, Ok Pyo,Jung, Young Hoon
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p. 4395 - 4402
(2007/10/03)
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- N-nitroso-N,O-dialkylhydroxylamines: Preparation, structure, and mechanism of the hydronium ion catalysed solvolytic nitrous oxide extrusion reaction
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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.
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p. 1435 - 1446
(2007/10/03)
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- 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
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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
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p. 7716 - 7730
(2007/10/03)
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- Efficient reductive etherification of carbonyl compounds with alkoxytrimethylsilanes
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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
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p. 4367 - 4370
(2007/10/02)
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- A convenient synthesis of methyl- and isopropyl-benzyl ethers using silver(II) oxide as reagent
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Substituted bromomethyl- and chloromethylbenzenes and bis(bromomethyl) benzenes were directly converted, in high yields, to the corresponding methyl- and isopropyl-benzyl ethers by treatment with silver(II) oxide in methanol or isopropanol.
- Ortiz,Walls,Yuste,Barrios,Sanchez-Obregon,Pinelo
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p. 749 - 756
(2007/10/02)
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- The Reduction of Nitrile with 2-Propanol over Hydrous Zirconium Oxide
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The vapor-phase reduction of nitriles with 2-propanol proceeded efficiently over hydrous zirconium oxide to give the corresponding alcohols in high yields.
- Takahashi, Kyoko,Shibagaki, Makoto,Matsushita, Hajime
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p. 311 - 314
(2007/10/02)
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- Generation of Organic Cations from Group 14 Organometallic Compounds via Photoinduced Electron Transfer in the Presence of Cu(II) Salt
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Irradiations of acetonitrile-alcohol (3:1) solutions of arylmethyl silanes, germane, or stannanes in the presence of Cu(BF4)2 gave alkyl arylmethyl ethers in good yields via arylmethyl cations, The efficiency of this photoreaction increased in the order of Si- Ge- Sn-compounds.
- Mizuno, Kazuhiko,Yasueda, Masahiro,Otsuji, Yoshio
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p. 229 - 232
(2007/10/02)
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- Gas-Phase Wittig Rearrangement of Carbanions Derived from Benzyl Ethers
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The CA mass spectra of ions PhC-HOR and Ph(R)CH-O- (R = alkyl and phenyl) are very similar, suggesting that the Wittig rearrangement PhC-HOEt -> Ph(Et)CH-O- occurs in the gas phase.Major fragmentation can be interpreted in terms of 1,2-elimination of groups from the Wittig product ion.For example, 2H labeling of PhC-HOEt and Ph(Et)CH-O- show that the major processes produce Me-CH=CH-O- + C6H6 and (C6H4)-CHO + C2H6, with the latter process involving prior scrambling of phenyl hydrogens.An analogous process, Ph2CH-O- -> (C6H4)-CHO + C6H6 gives the major peak in the spectrum of "PhC-HOPh".
- Eichinger, Peter C. H.,Bowie, John H.,Blumenthal Thomas
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p. 5078 - 5082
(2007/10/02)
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- MODIFICATION OF SINGLET CARBENE REACTIVITIES BY SOLVENT
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The solvent effect on the reactivity of singlet carbenes has been investigated.Competition reactions between pairs of alcohols for arylcarbenes in various solvents indicates that the O-H insertion selectivity is influenced only by 1,4-dioxane.Thus, phenylcarbene is some 33 times more reactive toward methanol relative to t-butyl alcohol in 90 molpercent dioxane than without solvent.Similar competition reactions between alcohol and olefin indicate that the O-H insertion-addition selectivities of arylcarbenes are considerably altered by dioxane.These results are interpreted as indicating that dioxane stabilizes singlet carbenes by complexing with its ione pairs of electrons.
- Tomoika, H.,Ozaki, Y.,Izawa, Y
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p. 4987 - 4994
(2007/10/02)
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- THE EFFECT OF ARYL SUBSTITUENTS ON ARYLCARBENE REACTIVITY
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Substituted (p-MeO, p-Me, H, p-Cl, p-Br, m-Br, m-MeO, 3,4-Cl2, p-CO2Me, m-CN and p-CN) monophenylcarbenes are generated in a binary mixture of substrates (methanol, cis-4-methyl-2-pentene and cyclohexane) and the relative rate of O - H insertion into methanol to stereospecific cyclopropanation of the olefin to C - H insertion into cyclohexane are calculated from the ratios of products and substrates.It is found (i) that the reactivities of the substrates decrease in the order of methanol, olefin and cyclohexane and (ii) that electron-donating substituents generally lead to reaction with the more reactive substrates while the reaction with the less reactive substrates is favoured in the case of electron-withdrawing substituents.These results are interpreted in terms of the change in the electrophilicity of the singlet arylcarbene by the substituents rather than the change in the singlet-triplet equilibrium.
- Tomioka, Hideo,Tabayashi, Kazuo,Ozaki, Yasuji,Izawa, Yasuji
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p. 1435 - 1440
(2007/10/02)
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- Effects of Substituents and Generation Methods on Insertion-Addition Selectivities of ''Arylcarbene'' in Alcohol-Olefin Binary Mixtures. Intervention of Reaction of Diazo Compounds Masquerading as Carbenes
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A Hammett study of the insertion-addition selectivity (Ki/ka) and cyclopropanation stereoselectivity (kc/kt) of "arylcarbene" generated either photolytically or thermally in 2-propanol-ethyl vinyl ether binary mixtures showed that ρ values are highly sensitive to the generation method.Thus, plots of ki/ka and kc/kt vs. ? (?+) in the photolytic run gave ρ values of -0.96 (r = -0.96) and -0.15 (r = -0.95), respectively, whereas similar values are +1.4 (r = 0.93) and -1.1 (r = -0.96) in the thermal run.The results along with the effects of precursor, temperature, and sensitizer on the product distributions are interpreted as indicating that, while free carbene is involved in the photolytic run, the ground-state diazo compound is masquerading as carbene in its thermal reaction with the olefin.
- Tomioka, Hideo,Suzuki, Shinji,Izawa, Yasuji
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p. 1047 - 1050
(2007/10/02)
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- Temperature and Substituent Effects on Regioselectivity in the Insertion of Arylcarbene into Alcohols
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Photolysis of aryldiazomethanes in methanol, ethanol, and 2-propanol gave OH insertion products along with small amounts of CH insertion products at ambient temperature.However, the CH insertion products increased significantly at the expense of the ether as the temperature was lowered.The attempted sensitized decomposition of the diazomethane did not lead to an increase in the CH insertion products presumably because of a rapid singlet-triplet equilibrium.The key intermediate leading to the CH insertion is suggested to be ground-state triplet arylcarbene, based on the accumulated spectroscopic as well as chemical evidence for the intervention of the triplet arylcarbene in the low-temperature photolysis of aryldiazomethanes.Substituents on the phenyl ring also have an appreciable effect on the insertion selectivity.At room temperature, the OH/CH insertion selectivity increased with the electron-donating ability of the substituents.This is interpreted in terms of the substituent effect on the transition state of OH insertion, where there is a deficiency of electrons at the benzylic carbon atom, rather than on the stability of singlet carbene.At low temperature, both electron-donating and -withdrawing substituents facilitate OH insertion, indicating the change in substituents induces a concomitant change in the insertion mechanism, presumably due to decreasing nucleophilicity of carbene with increasing electron-withdrawing ability as well as decreasing proton-donor activity of alcohol with decreasing temperature.This may also reflect the effect of the substituent on the singlet-triplet energy gap.
- Tomioka, Hideo,Suzuki, Shinji,Izawa, Yasuji
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p. 3156 - 3162
(2007/10/02)
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- New Conversion of Esters to Ethers and Its Application to the Preparation of Furano-18-crown-6
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Thionoesters which are readily prepared from esters can be desulfurized with Raney nickel to form the corresponding ethers.This new synthetic pathway to convert esters to ethers avoids many of the steric and functional limitations of known methods and appears to be a general method for this conversion.
- Baxter, Steven L.,Bradshaw, Jerald S.
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p. 831 - 832
(2007/10/02)
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