- Stereoelectronic effects: Perlin effects in cyclohexane-derived compounds
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Stereoelectronic effects in cyclohexanones, methylenecyclohexanes, spiro, and epoxy compounds of cyclohexanes and further derivatives were investigated by measuring 1JC,H coupling constants and by identification of Perlin effects, th
- Jung, Sebastian T.,Nickisch, Roman,Reinsperger, Tony,Luy, Burkhard,Podlech, Joachim
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- Synthesis of nitrogen-containing monoterpenoids with antibacterial activity
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Incorporation of the Beckmann rearrangement into the presented research resulted in the formation of nitrogen-containing terpenoid derivatives originating from naturally occurring compounds. Both starting monoterpenes and obtained derivatives were subjected to estimation of their antibacterial potential. In the presented study, Staphylococcus aureus was the most sensitive to examined compounds. The Minimal Inhibitory Concentration (MIC) experiments performed on S. aureus demonstrated that the (?)-menthone oxime (?)-8 and (+)-pulegone oxime (+)-13 had the best antibacterial activity among the tested derivatives and starting compounds. Their MIC90 value was 100 μg/mL. The obtained derivatives were also evaluated for their inhibitory activity against bacterial urease. Among the tested compounds, three active inhibitors were found–oxime 14 and lactams (?)-15 and 16 limited the activity of Sporosarcina pasteurii urease with Ki values of 174.3 μM, 43.0 μM and 4.6 μM, respectively. To our knowledge, derivative 16 is the most active antiureolytic lactam described to date.
- Grabowiecka, Agnieszka,Grela, Ewa,Macegoniuk, Katarzyna,Kozio?, Agata,Lochyński, Stanis?aw
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supporting information
p. 1074 - 1079
(2019/01/29)
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- Application of Transaminases in a Disperse System for the Bioamination of Hydrophobic Substrates
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The challenging bioamination of hydrophobic substrates has been attained through the employment of a disperse system consisting of a combination of a low polarity solvent (e. g. isooctane or methyl-tert-butylether), a non-ionic surfactant and a minimal amount of water. In these conditions, amine transaminases (ATA) were shown to efficiently carry out the reductive amination of variously substituted cyclohexanones, providing good conversions often coupled with a superior stereoselectivity if compared with the corresponding chemical reductive amination. An array of synthetically useful 4-substituted aminocyclohexanes was consequentially synthesized through biocatalysis, analyzed and stereochemically characterized. (Figure presented.).
- Berglund, Per,Fiorati, Andrea,Humble, Maria S.,Tessaro, Davide
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- Arylboronic Acid-Catalyzed C-Allylation of Unprotected Oximes: Total Synthesis of N-Me-Euphococcine
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O-Unprotected keto-and aldoximes are readily C-allylated with allyl diisopropyl boronate in the presence of arylboronic acid catalysts to yield highly substituted N-α-secondary and tertiary homoallylic hydroxylamines. The method was used in the total synthesis of the trace alkaloid N-Me-Euphococcine.
- Kürti, László,Kattamuri, Padmanabha V.,Siitonen, Juha H.,Yousufuddin, Muhammed
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supporting information
(2020/03/24)
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- Aliphatic C-H Bond Oxidation with Hydrogen Peroxide Catalyzed by Manganese Complexes: Directing Selectivity through Torsional Effects
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Substituted N-cyclohexyl amides undergo aliphatic C-H bond oxidation with H2O2 catalyzed by manganese complexes. The reactions are directed by torsional effects leading to site-selective oxidation of cis-1,4-, trans-1,3-, and cis-1,2-cyclohexanediamides. The corresponding diastereoisomers are unreactive under the same conditions. Competitive oxidation of cis-trans mixtures of 4-substituted N-cyclohexylamides leads to quantitative conversion of the cis-isomers, allowing isolation and successive conversion of the trans-isomers into densely functionalized oxidation products with excellent site selectivity and good enantioselectivity.
- Milan, Michela,Bietti, Massimo,Costas, Miquel
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supporting information
p. 2720 - 2723
(2018/05/22)
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- Directing Group in Decarboxylative Cross-Coupling: Copper-Catalyzed Site-Selective C-N Bond Formation from Nonactivated Aliphatic Carboxylic Acids
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Copper-catalyzed directed decarboxylative amination of nonactivated aliphatic carboxylic acids is described. This intramolecular C-N bond formation reaction provides efficient access to the synthesis of pyrrolidine and piperidine derivatives as well as the modification of complex natural products. Moreover, this reaction presents excellent site-selectivity in the C-N bond formation step through the use of directing group. Our work can be considered as a big step toward controllable radical decarboxylative carbon-heteroatom cross-coupling.
- Liu, Zhao-Jing,Lu, Xi,Wang, Guan,Li, Lei,Jiang, Wei-Tao,Wang, Yu-Dong,Xiao, Bin,Fu, Yao
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supporting information
p. 9714 - 9719
(2016/08/11)
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- Oxidation of primary amines to oximes with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO3/Al2O3 as catalysts
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The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O2/N2 = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO3/Al2O3 gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6.
- Suzuki, Ken,Watanabe, Tomonari,Murahashi, Shun-Ichi
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p. 2301 - 2310
(2013/04/24)
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- Structure correlation study of the beckmann rearrangement: X-ray structural analysis and 13C-13C 1-bond coupling constant study of a range of cyclohexanone oxime derivatives
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The X-ray structures of a range of oxime derivatives (1 and 4), of cyclohexanone and 4-tert-butylcyclohexanone, where the electron demand of the oxygenated substituent on the oxime nitrogen (OR) is systematically varied were determined. It was established
- Yeoh, Shin Dee,Harris, Benjamin L.,Simons, Tristan J.,White, Jonathan M.
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body text
p. 905 - 917
(2012/09/22)
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- A simple synthesis of oximes
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The conversion of alicyclic and aliphatic carbonyl compounds as well as aromatic aldehydes into the corresponding oximes (up to quantitative yields) was achieved by simply grinding these reactants, hydroxylamine hydrochloride and sodium hydroxide without solvent. However, this procedure was unsuccessful in the case of aromatic ketones. In this case it was necessary to add silica gel as a catalyst. Springer-Verlag 2006.
- Damljanovic, Ivan,Vukicevic, Mirjana,Vukicevic, Rastko D.
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p. 301 - 305
(2007/10/03)
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- Chlorination of oximes with aqueous H2O2/HCl system: Facile synthesis of gem-chloronitroso- and gem-chloronitroalkanes, gem-chloronitroso- and gem-chloronitrocycloalkanes
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Chlorination of cyclic and linear ketone oximes with aqueous H 2O2/HCl in a two-phase dichloromethane-water system selectively affords gem-chloronitroso compounds in yields of up to 94%. One-pot oxidation of the resulting gem-chloronitroso compounds with peracetic acid, prepared in situ, gives gem-chloronitroalkanes and cycloalkanes in yields of up to 82%. The advantages of the method are that it is facile and environmentally benign and does not require gaseous chlorine. Georg Thieme Verlag Stuttgart.
- Terent'ev, Alexander O.,Krylov, Igor B.,Ogibin, Yuri N.,Nikishin, Gennady I.
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p. 3819 - 3824
(2008/02/09)
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- Axial/equatorial populations in α-hetero-substituted cyclohexanone oximes and O-methyl oximes
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Axial equatorial populations were determined for (E)-2-X-cyclohexanone oximes and O-methyl oxime ethers in chloroform by the Eliel method [X = F, Cl, Br, OCH3, N(CH3)2, SCH3]. A novel approach is presented, whic
- Ribeiro, Douglas S.,Olivato, Paulo R.,Rittner, Roberto
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p. 627 - 638
(2007/10/03)
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- Stereoselective hydride reductions of cyclic N-diphenylphosphinyl imines. Highly diastereoselective syntheses of protected primary amines
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Reduction of N-diphenylphosphinyl imines of variously substituted cyclohexanones, cyclopentanones, and bicyclic ketones with lithium tri-sec-butylborohydride provides highly diastereoselective procedures for the syntheses of N-diphenylphosphinyl amines which represent protected primary amines that can be unmasked by mild acidic cleavage. Attack of cyclohexyl derivatives occurs almost exclusively via equatorial approach to yield axial amine derivatives while cyclopentyl and bicyclic imines are attacked from the less sterically encumbered faces.
- Hutchins,Adams,Rutledge
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p. 7396 - 7405
(2007/10/03)
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- REACTION D'OXIMATION DES CETONES V. MECANISME ET EFFETS DE STRUCTURE DANS LA REACTION DE DESHYDRATATION ACIDO-CATALYSEE DES CARBINOLAMINES
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The equilibrium constants of formation and the rate constants of dehydratation of carbinolamines resulting from the addition of hydroxylamine to 19 ketones, - 5 aliphatic, 5 aromatic and 9 cyclanic -, have been measured at 25 deg C in water/methanol 60/40 v/v.We show that the acid catalyzed process predominates in the range of pH 6 to 7 for acetophenones or pH 7 to 8.5 for saturated ketones.The rate constants ratios and Hammett ρ constant of the reaction suggest an sp3 (early) transition state.The changes in rate constant are discussed in terms of torsional and non-bonding steric effects.For several hindered ketones, e.g. 3,3,5,5-tetramethylcyclohexanone, we show the existence of a steric hindrance to the approach of the catalyst; in that case the result is a strong decrease of the rate of the dehydratation.
- Lamaty, G.,Roque, J. P.,Natat, A.,Silou, T.
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p. 2667 - 2676
(2007/10/02)
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- The Photochemistry of α,β-Unsaturated Nitro Compounds and Nitronic Acids. Concerning Deconjugation and α,β-Unsaturated Ketone Formation
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The photochemistry of cyclohexylidenenitromethane (6), 3-ethyl-2-nitropent-2-ene (7), (Z)-α-methyl-α'-nitrostilbene (12), (E)-3-methyl-1-nitro-1-phenylbut-1-ene (15) and 4,4-dimethyl-3-nitro-5α-cholest-2-ene (27) has been examined to determine the structural features required for deconjugation to the β,γ-unsaturated isomer.The mechanism of the light-induced formation of the corresponding α,β-unsaturated ketone, which may accompany deconjugation, has also been examined.Support for a scheme involving γ-hydrogen abstraction to give an unsaturated nitronic acid, followed by N-hydroxyoxaziridine formation and collapse to the ketone, is provided in the photochemistry of the stable nitronic acids, 4-t-butyl-aci-nitrocyclohexane (17) and 9-aci-nitrofluorene (18).Syntheses of the nitro olefins (6), (7), (12), (15) and (27), and the nitronic acid (17) are also reported.
- Grant, Richard D.,Pinhey, John T.,Rizzardo, Ezio,Smith, Geoffrey C.
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p. 1505 - 1519
(2007/10/02)
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- Stereoselective Reductions of Substituted Cyclohexyl and Cyclopentyl Carbon-Nitrogen ? Systems with Hydride Reagents
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Reductions of 3- and 4-substituted cyclohexyl imines, iminium salts, and enamines (via iminium ions) with various hydride reagents reveal that while small reagents (NaBH4, NaBH3CN) favor axial approach as observed with the corresponding ketones, even moderately bulky reagents (i.e., acetoxyboranes) attack preferentially from the equatorial side.This is in direct contrast to the results observed for the same reagents with the corresponding ketones and is interpreted as implying that additional steric interactions induced by the nitrogen substituents encumber axial attack by substituted hydride reagents and force approach from the equatorial direction.The very bulky tri-sec-butylborohydride anion affords highly stereodiscriminating equatorial attack.Reductions of 2-alkylcyclohexyl and 2-alkylcyclopentyl imines and enamines also proceed with high stereoselectivity to give cis-2-alkyl cyclic amines with both hindered and unhindered reagents.This is interpreted to be the result of (1) augmented steric interactions between nitrogen substituents and equatorial 2-alkyl groups (1,3-allylic strain) which induces conformational changes to favor the axial 2-alkyl conformer and (2) hindrance toward equatorial approach by reagents induced by axial alkyl substituents.The result is that equatorial approach is favored with equatorial 2-alkyl conformers and preferential axial approach with axial 2-alkyl conformers, leading to stereoselective production of cis-2-alkylamines. trans-2-n-Propyl-4-tert-butylcyclohexanone is reduced by LiBH(sec-Bu)3 preferentially from the axial direction in contrast to the usual highly selective equatorial attack observed with other cyclohexanones.
- Hutchins, Robert O.,Su, Wei-Yang,Sivakumar, Ramachandran,Cistone, Frank,Stercho, Yuriy P.
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p. 3412 - 3422
(2007/10/02)
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- NITROXYDES 94: DECOMPOSITION THERMIQUE D'UN RADICAL OXAZOLIDINE-OXYLE.
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Pyrolysis of spiro 1 leads to spiro 2, 4-t-butyl cyclohexanone and 4-t-butyl cyclohexanoxime.Kinetic studies show that the reaction proceeds through an autocatalytic process.
- Michon, Josette,Rassat, Andre
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p. 1949 - 1952
(2007/10/02)
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