- Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
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A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
- Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
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supporting information
p. 9925 - 9937
(2021/06/30)
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- To Rebound or...Rebound? Evidence for the "alternative Rebound" mechanism in Ca'H Oxidations by the systems nonheme Mn Complex/H2O2/carboxylic acid
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In this work, it has been shown that aliphatic Ca'H oxidations by bioinspired catalyst systems Mn aminopyridine complex/H2O2/carboxylic acid in acetonitrile afford predominantly a mixture of the corresponding alcohol and the ester. The alcohol/ester ratio is higher for catalysts bearing electron-donating groups at the aminopyridine core. Isotopic labeling studies witness that the oxygen atom of the alcohol originates from the H2O2molecule, while the ester oxygen comes exclusively from the acid. Oxidation of ethylbenzene in the presence of acetic acid affords enantiomerically enriched 1-phenylethanol and 1-phenyl acetate, with close enantioselectivities and the same sign of absolute chirality. Experimental data and density functional theory calculations provide evidence in favor of the rate-limiting benzylic H atom abstraction by the high-spin (S = 1) [LMnV(O)OAc]2+active species followed by competitive OH/OC(O)R rebound. This mechanism has been unprecedented for Ca'H oxidations catalyzed by bioinspired Mn complexes. The trends governing the alcohol/ester ratios have been rationalized in terms of steric properties of the catalyst, acid, and substrate. copy; 2021 American Chemical Society.
- Ottenbacher, Roman V.,Bryliakova, Anna A.,Shashkov, Mikhail V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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p. 5517 - 5524
(2021/05/31)
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- Diester acid protection structure monomer and preparation method thereof
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The invention relates to the field of optical materials and in particular to a diester acid protection structure monomer and a preparation method thereof. The diester acid protection structure monomeris used as a raw material of a photoresist required in integrated circuit manufacturing. Due to a diester long side chain, the photoresist has a better film-forming property; due to the fact that small-size and high-acid-sensitivity groups hung outside can improve the deprotection reaction efficiency in the photoetching process, the quality of a photoetched product is improved; and in addition, the diester acid protection structure monomer prepared through the process method has high yield and purity, and the performance of the photoresist is further guaranteed.
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Paragraph 0076-0082; 0096-0102; 0106-0112; 0119-0125
(2020/01/03)
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- Controllable Intramolecular Unactivated C(sp3)-H Amination and Oxygenation of Carbamates
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Dual catalyst-controlled intramolecular unactivated C(sp3)-H amination and oxygenation of carbamates merging visible-light photocatalysis and earth-abundant transition metal catalysis have been reported. Useful amino alcohol and diol derivatives could be selectively obtained from readily available tertiary alcohol derivatives. The possible mechanisms have been proposed via a 1,5-HAT process followed by Lewis acid-controlled cyclization. The nickel and zinc catalysts inhibit the formation of oxygenation and amination products, respectively. An interesting phenomenon of chirality transfer is also observed.
- Guo, Qihang,Ren, Xiang,Lu, Zhan
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supporting information
p. 880 - 884
(2019/05/16)
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- PROCESS FOR THE PREPARATION OF 1-METHYLCYCLOPENTANE DERIVATIVES
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Process for the preparation of 1-methylcyclopentene by thermal reaction of cyclohexanol or cyclohexene or mixtures of both compounds to give 1-methylcyclopentene, wherein the resulting by-products 3-methylcyclopentene and 4-methylcyclopentene (double-bond isomers of 1-methylcyclopentene) are returned to the reaction.
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- PROCESS FOR THE PREPARATION OF 1-METHYL-1-ALKOXYCYCLOPENTANES
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Process for the preparation of cyclopentane derivatives of the formula I in which R is a C1- to C10-alkyl group, which comprises reacting cyclohexanol or cyclohexene or mixtures of both compounds to give 1-methyl-1-cyclopentene (1st stage) and subsequently adding a C1- to C10-alkanol onto the double bond of the 1-methyl-1-cyclopentene (2nd stage).
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- Di(hydroxo)porphyrin GeIV complex/silica gel composite as visible light-assisted radical generator
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A composite of di(hydroxo)germaniumporphyrin with silica gel was used as radical generator which oxidized MeOH to HCHO and hydrocarbons to alcohols in aqueous solution.
- Shiragami, Tsutomu,Shiraki, Ryuichi,Makise, Ryuichi,Matsumoto, Jin,Yasuda, Masahide
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body text
p. 874 - 875
(2011/01/10)
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- Stereoselective synthesis of δ-lactones from 5-oxoalkanals via one-pot sequential acetalization, tishchenko reaction, and lactonization by cooperative catalysis of samarium ion and mercaptan
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By the synergistic catalysis of samarium ion and mercaptan, a series of 5-oxoalkanals was converted to (substituted) δ-lactones in efficient and stereoselective manners. This one-pot procedure comprises a sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reaction mechanism and stereochemistry are proposed and supported by some experimental evidence. Such samarium ion/mercaptan cocatalyzed reactions show the feature of remote control, which is applicable to the asymmetric synthesis of optically active δ-lactones. This study also demonstrates the synthesis of two insect pheromones, (2S,5R)-2-methylhexanolide and (R)-hexadecanolide, as examples of a new protocol for asymmetric reduction of long-chain aliphatic ketones.
- Hsu,Fang
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p. 8573 - 8584
(2007/10/03)
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- Hydrosilylation of 1-methylcyclopentene
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Hydrosilylation of 1-methylcyclopentene with chloromethylsilanes Me3-nSiHCln (n = 2, 3) yields dichloro(cyclopentylmethyl)methyl-and trichloro(cyclopentylmethyl)silanes, respectively. Chlorodimethylsilane (n = 1) adds to 1-methylcyclopentene to give a mixture of cis-and trans-chloro(methyl)(2-methylcyclopentyl)silanes, as well as chloro(cyclopentylmethyl)methylsilane. The hydrosilylation products were reacted with ethynylmagnesium bromide to prepare the corresponding ethynyl derivatives. Reaction of (cyclopentylmethyl)triethynylsilane with ethylmagnesium bromide and chlorotrimethylsilane gave (cyclopentylmethyl)tris(trimethylsilylethynyl)silane.
- Yarosh,Zhilitskaya,Yarosh,Albanov,Burnashova,Voronkov
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p. 1395 - 1397
(2007/10/03)
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- Process for preparing omega-halo-ketones
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A process for preparing 6-chloro-2-hexanone which comprises the steps of (a) dehydrating cyclohexanol in the presence of a suitable catalyst and at a suitable temperature and for a sufficient period of time to form cyclohexene; (b) rearranging said cyclohexene at a higher temperature than in step (a) in the presence of a suitable catalyst and for a sufficient period of time to form 1-methylcyclopentene; (c) hydrating said 1-methylcyclopentene at a temperature lower than step (b) and in the presence of a resin catalyst for a sufficient period of time to form 1-methylcyclopentanol; (d) reacting said 1-methylcylcopentanol with a suitable amount of an alkali metal hypochlorite in the presence of a carboxylic acid to form 1-methylcyclopentyl hypochlorite; and (e) heating said 1-methylcyclopentyl hypochlorite for a sufficient period of time to form 6-chloro-2-hexanone.
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- Process for preparing alkanols
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A process for preparing tertiary alkanols which comprises the step of oxidizing with ozone a saturated hydrocarbon having a tertiary carbon center in the presence of a carboxylic acid and for a sufficient period of time and at suitable temperature and pressure to form said alkanols.
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- Process for preparing 6-chloro-2-hexanone from 1-methylcyclopentane
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A process for preparing 6-chloro-2-hexanone which comprises the steps of (a) oxidizing methylcyclopentane with ozone in the presence of a carboxylic acid and for a sufficient period of time to form 1-methylcyclopentanol; (b) reacting said 1-methylcyclopentanol with a suitable amount of an alkali metal hypochlorite in the presence of a carboxylic acid to form 1-methylcyclopentyl hypochlorite; and (c) heating said 1-methylcyclopentyl hypochlorite for a sufficient period of time to form 6-chloro-2-hexanone.
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- Synthesis and Occurrence of Oxoaldehydes in Used Frying Oils
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As part of our efforts to identify volatile decomposition products in used frying oils, a series of 4- and 5-oxoaldehydes were synthesized, purified, and characterized by gas chromatography, gas chromatography-mass spectrometry, gas-chromatography-Fourier transform infrared spectrometry, and nuclear magnetic resonance spectrometry.Oxoaldehydes have been proposed as possible precursors of alkylfurans, which have potential anticancer effects.In a model reaction 4-oxononanal was refluxed in hexane for 40 days and only trace amounts of 2-pentylfuran were produced, suggesting that it is not a major precursor of the furan.The volatile constituents of used frying oils obtained from commercial food processors were studied, and 4-oxohexanal, 4-oxooctanal, 4-oxononanal, and 4-oxodecanal were identified.Keywords: Oxoaldehydes; odor threshold; frying oil
- Takeoka, Gary R.,Buttery, Ron G.,Perrino, Charles T.
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- Dichloromethane as a source of the CH22-synthon: A combination of an arene-catalysed lithiation and a barbier-type reaction
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The reaction of dichloromethane 1 with an excess of lithium powder (1:7 molar ratio) and catalytic amount of 4,4'-di-tert-butylbiphenyl (5 mol %) in the presence of a carbonyl compound 2 (1:2 molar ratio) in tetrahydrofuran at -40°C yields, after hydrolysis, the corresponding 1,3-diols 3 in moderate yields. The process can be also applied to more complicated gem-dichloro derivatives such as 7,7-dichlorobicyclo[4.1.0]heptane 6 or methyl dichloromethyl ether 9.
- Guijarro, Albert,Vus, Miguel
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p. 253 - 256
(2007/10/02)
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- INSECT PHEROMONES AND THEIR ANALOGUES. XXXV. SYNTHESIS OF (R)-(-)-10-METHYLTRIDECAN-2-ONE - THE PHEROMONE OF Diabrotica undecimpunctata
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A scheme has been developed for the synthesis of (R)-(-)-10-methyltridecan-2-one, the sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata) using as the chiral synthon (R)-(+)-methylheptenal obtained by the hydroperoxide oxidation of the readily available (S)-(+)-dihydromyrcene.
- Odinokov, V. N.,Kukovinets, O. S.,Kasradze, V. G.,Tsyglintseva, E. Yu.,Serebryakov, E. P.,Tolstikov, G. A.
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p. 106 - 109
(2007/10/02)
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- Direct Formation and Subsequent Substitution of Remote Ketone-Functionalized Organocopper Reagents
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Remote ketone-functionalized aryl- and alkylcopper reagents have been synthesized by the use of a highly activated form of zero-valent copper. 5-Bromo-2-pentanone and 4-iodobenzophenone undergo oxidative addition with activated copper to form 5-cuprio-2-pentanone and 4-cupriobenzophenone, respectively.These, in turn, can be cross-coupled with alkyl halides to produce the corresponding alkylated ketones and with acid chlorides to form the corresponding diketones.By use of this methodology, a two-step, one-pot synthesis of methyl (E)-9-oxo-2-decenoate and 8-nonen-2-one have been achieved.The former compound is the methyl ester of the "queen substance" of the honey bee, and the latter is part of an "attractant mixture" for cheese mites found in cheddar cheese.These syntheses were accomplished by converting commercially available 6-bromo-2-hexanone to 6-cuprio-2-hexanone followed by cross-coupling with commercially available methyl 4-bromocrotonate and allyl bromide, respectively.
- Ebert, Greg W.,Klein, Walter R.
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p. 4744 - 4747
(2007/10/02)
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- NEW ORGANOCOPPER REAGENTS PREPARED UTILIZING HIGHLY REACTIVE COPPER
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Highly reactive copper solutions have been prepared by the lithium naphthalide reduction of copper(I) iodide/trialkylphosphine complexes.These activated copper solutions will react with organic halides under very mild conditions to form stable organocopper reagents.Significantly, the organocopper reagents can contain considerable functionalities such as ester, nitrile, chloride, epoxide, and ketone groups.These functionalized organocopper species undergo many reactions typical of other organocopper species.Intermolecular 1,4-additions, epoxide-opening reactions, and ketone formation with acid chlorides have been successfully achieved.In addition, this methodology has been applied to an intramolecular epoxide-cleavage reaction.The influence of the connecting chain length, substitution pattern, reaction solvent, and CuI/phosphine complex upon the regioselectivity of the intramolecular cyclization is described.
- Rieke, Reuben D.,Wehmeyer, Richard M.,Wu, Tse-Chong,Ebert, Greg W.
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p. 443 - 454
(2007/10/02)
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- FUNCTIONALISATION OF SATURATED HYDROCARBONS. Part X. A COMPARATIVE STUDY OF CHEMICAL AND ELECTROCHEMICAL PROCESSES (GIF AND GIF-ORSAY SYSTEMS) IN PYRIDINE, IN ACETONE AND IN PYRIDINE-CO-SOLVENT MIXTURES
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Six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis- and trans-decalin and adamantane) were oxidised by the Gif system (iron catalyst, oxygen, zinc, carboxylic acid) and its electrochemical equivalent (Gif-Orsay system).Results obtained using various solvents (pyridine, acetone, pyridine-acetone mixtures) were similar for both systems.Total or partial replacement of pyridine with acetone affects the selectivity for secondary positions and lowers the ketone/secondary alcohol ratio.The formation of the same ratio of cis- and trans-decal-9-ol from both cis- and trans-decalin clearly demonstrates that tertiary alcohols result from a mechanism essentially radical in nature.
- Belavoine, Gilbert,Barton, Derek H. R.,Boivin, Jean,Gref, Aurore,Coupanec, Pascale Le,et al.
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p. 1091 - 1106
(2007/10/02)
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- DIRECT FORMATION OF EPOXYALKYLCOPPER REAGENTS FROM ACTIVATED COPPER AND EPOXYALKYL BROMIDES AND THEIR INTRAMOLECULAR CYCLIZATIONS
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Epoxyalkylcopper compounds have readily been prepared by the direct oxidative addition of active copper to epoxyalkyl halides.The intramolecular cyclization of the epoxyalkylcopper reagents via an epoxide cleavage process is described.Significantly, many functional groups can be present in the bromoepoxides yielding highly functionalized carbocycles.The regioselectivity of this cyclizations is affected by the connecting chain length, substitution pattern, reaction solvent, and the CuI-phosphine complex used to generate the copper.
- Wu, Tse-Chong,Rieke, Reuben D.
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p. 6753 - 6756
(2007/10/02)
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- Cycloalkyl esters of mercaptoalkanoic acids
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Described are the cycloalkyl esters of mercaptoalkanoic acids defined according to the structure: STR1 wherein R1 represents hydrogen or methyl; R2 represents mono C1 -C4 alkyl substituted or unsubstituted C5 -C8 cycloalkyl; R3 represents hydrogen or methyl; and N represents 0, 1 or 2 and uses thereof in augmenting or enhancing the aroma or taste of foodstuffs.
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- REGIOCHEMISTRY OF THE METAL-HALOGEN EXCHANGE INDUCED CYCLIZATION OF ω-IODOEPOXIDES
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The regiochemistry of the cyclization reactions of some ω-lithioepoxides as a function of chain length and substitution pattern has been examined.Striking changes in regiochemistry have been observed in the presence of certain Lewis acids and metal halides.
- Cooke, Manning P.,Houpis, Ioannis N.
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p. 3643 - 3646
(2007/10/02)
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- METAL-HALOGEN EXCHANGE-INITIATED CYCLIZATION OF IODO CARBONYL COMPOUNDS
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The feasability of constructing carbocycles through the metal-halogen exchange-initiated cyclization reactions of iodoketones and other carboxyl derivatives has been studied.With saturated primary iodides, cyclization predominates when deactivated ketones are employed.
- Cooke, Manning P.,Houpis, Ioannis N.
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p. 4987 - 4990
(2007/10/02)
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- DIRECT PHOTOLYSIS AT 185 nm OF 1-ALKENES IN SOLUTION. MOLECULAR ELIMINATION OF TERMINAL HYDROGENS
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Direct irradiations at 185 nm of 1-octene and 2-methyl-1-pentene in pentane gave alkylidene carbenes through the molecular elimination of terminal hydrogens, as well as double-bond migration products via 1,3-shift of allylic hydrogen and radical-derived products.
- Inoue, Yoshihisa,Mukai, Toshio,Hakushi, Tadao
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p. 1725 - 1728
(2007/10/02)
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- Does the Cyclohehyl Cation Exist in the Dilute Gas State? Direct Evidence from a Radiolytic Study
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The isomeric composition of the daseous C6H11+ cations obtained via hydride ion abstraction from c-C6H12 has been investigated by allowing the charged species to react in the gas phase with water and analyzing the neutral products formed.The nature and the yields of the major products, cyclohexanol, cyclohexanone, and 1-methylcyclopentanol, and their dependence on the pressure and the composition of the gaseous system provide direct evidence for the existence of the cyclohexyl cation in the dilute gas state, with a lifetime in excess of 10-7 s, and confirm its facile rearrangement to the more stable 1-methylcyclopentyl ion.
- Attina, Marina,Cacace, Fulvio,Giacomello, Pierluigi
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p. 4711 - 4714
(2007/10/02)
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- Studies on the Autoxidation of Some Monocyclic Olefins
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The autoxidations of cyclopentene, cyclohexene, cycloheptene, cyclooctene, cycloocta-1,5-diene, 1-methylcyclopentene, 1-methylcyclohexene, 1-methylcycloheptene, 1-methylcyclooctene, methylene cyclopentene, and methylene cyclohexene with pure oxygen under normal pressure were studied.The epoxides formed were determined gaschromatographically.In most cases also the products of allylic oxidation were analyzed and their structures elucidated after reduction to the corresponding allyl alcohols.The portions of high boiling or polymeric products which could not be detected gaschromatographically and also the real yields of epoxides were determined by balance experiments in the presence of inert internal standards.
- Blau, K.,Mueller, U.,Pritzkow, W.,Schmidt-Renner, W.,Sedshaw, Z.
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p. 915 - 932
(2007/10/02)
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- Some studies on the solvolysis of 1-chloro-1-alkyl cycloalkanes
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The effect of the bulk of the sidechain on the rate of solvolysis of 1-alkyl cyclopentyl, cyclohexyl, and cycloheptyl chlorides has been studied.With the exception of the t-butyl systems, the ratio of solvolysis rates for the three ring systems falls in a given series.The slower rate of solvolysis in the six-membered ring system may be due to an extra activation energy contribution caused by the conversion of a neutral chair form to the twist boat or half chair conformation, prior to the actual solvolysis.In the case of five- and seven-membered ring systems the formation of an intermediate carbonium ion is sterically favoured (I-strain or eclipsing interaction) consistent with earlier findings.The faster rate of solvolysis of 1-t-butylcycloalkyl chlorides is likely due to a rearrangement reaction where alkyl participation enhances the rate of solvolysis.
- Ranganayakulu, K.,Vasumathi Devi, M.,Balaji Rao, R.,Rajeswari, K.
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p. 1484 - 1489
(2007/10/02)
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- Methyl-triisopropoxy-titanium, a Highly Selective Nucleophilic Methylating Reagent
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Replacement of lithium or magnesium by titanium can furnish nucleophilic organometallic reagents of high selectivity as exemplified by the title compound 1 (see Tables 1-3).
- Weidmann, Beat,Seebach, Dieter
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p. 2451 - 2454
(2007/10/02)
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