- Oxygen surface groups of activated carbon steer the chemoselective hydrogenation of substituted nitroarenes over nickel nanoparticles
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Oxygen surface groups of activated carbon, produced by nitric acid treatment, are not only able to prevent Ni particles from sintering but are also able to preferentially interact with the nitro group of substituted nitroarenes. The resulting Ni/ACOX catalyst is highly active and chemoselective for hydrogenation of nitroarenes to produce functionalized anilines and oximes.
- Ren, Yujing,Wei, Haisheng,Yin, Guangzhao,Zhang, Leilei,Wang, Aiqin,Zhang, Tao
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- ASPARAGINE DERIVATIVES AND METHODS OF USE THEREOF
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The present invention relates to compounds of formulas (A) and (I), pharmaceutically acceptable salts thereof, and solvates of any of them, pharmaceutical compositions comprising them, methods of preparation thereof, intermediate compounds useful for the preparation thereof, and methods of treatment or prophylaxis of diseases, in particular cancer, such as colorectal cancer, using these. (A) (I)
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- Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
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An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20?000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18?600 and 19?200 h-1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10?000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated.
- Chen, Yang,Liu, Changmeng,Xu, Dong,Xu, Jiaxi,Yang, Zhanhui
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p. 6050 - 6058
(2021/08/23)
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- Copper-Catalyzed Aza-Sonogashira Cross-Coupling To Form Ynimines: Development and Application to the Synthesis of Heterocycles
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Nitrogen-substituted alkynes, such as ynamines and ynamides, are versatile synthetic building blocks. Ynimines bearing additional nucleophilic and electrophilic centers relative to ynamines and ynamides are expected to have high synthetic potential. However, their chemical reactivity remains unexplored owing mainly to the lack of synthetic accessibility. We report herein a versatile copper-catalyzed synthesis of ynimines from readily available O-acetyl ketoximes and terminal alkynes. A wide range of O-acetyl ketoximes derived from diaryl ketones, aryl alkyl ketones and dialkyl ketones underwent cross-coupling with a diverse set of terminal alkynes to afford the ynimines in good to excellent yields. An unprecedented [5+1] heteroannulation reaction exploiting the reactivity of the ynimine generated in situ was subsequently developed for the synthesis of medicinally important heterocycles, including isoquinolines, azaindoles, azabenzofurans, azabenzothiophenes and carbolines.
- Lavernhe, Rémi,Torres-Ochoa, Rubén O.,Wang, Qian,Zhu, Jieping
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supporting information
p. 24028 - 24033
(2021/10/07)
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- Modular 2,3-diaryl-2: H -azirine synthesis from ketoxime acetates via Cs2CO3-mediated cyclization
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A modular 2H-azirine synthesis from ketoxime acetates via Cs2CO3-mediated cyclization has been developed. The reaction utilizes easily available starting materials and provides a general synthetic route to 2,3-diaryl-2H-azirines in good to excellent yields under mild conditions, which is complementary to the conventional approaches for the synthesis of 2H-azirines. A gram-scale reaction was performed to demonstrate the scale-up applicability of this synthetic method. Importantly, 2H-azirines can be efficiently converted to various azaheterocycles.
- Zhao, Mi-Na,Zhang, Wei,Wang, Xu-Cai,Zhang, Ying,Yang, De-Suo,Guan, Zheng-Hui
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supporting information
p. 4333 - 4337
(2018/06/21)
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- Cathodic hydrodimerization of nitroolefins
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Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C-C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a β,β-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.
- Wessling, Michael,Sch?fer, Hans J.
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supporting information
p. 1163 - 1174
(2015/08/18)
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- ZnO Nanotube as reusable catalyst in the efficient and selective oximation reaction of carbonyl groups under solvent free conditions
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A convenient and efficient procedure for the selective protection of carbonyl groups in the presence of ZnO nanotube, as reusable eco-friendly catalyst under solvent free conditions is described. The salient features of this methodology are cheaper process, easy availability of the catalyst, versatility, and the catalyst can be recovered after completion of the reaction and can be recycled without affecting the catalytic property.
- Kiasat, Ali Reza,Javaherian, Mohammad,Daei, Mina,Farbod, Mansoor
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p. 875 - 880
(2015/11/24)
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- Visible-light-induced formal [3+2] cycloaddition for pyrrole synthesis under metal-free conditions
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A photocatalytic formal [3+2] cycloaddition of 2H-azirines with alkynes has been achieved under irradiation by visible light in the presence of organic dye photocatalysts. This transformation provides efficient access to highly functionalized pyrroles in good yields and has been applied to the synthesis of drug analogues. A primary trial of photocascade catalysis merging energy transfer and redox neutral reactions was shown to be successful. Photo(chemistry) op: A photocatalytic formal [3+2] cycloaddition of 2H-azirines with alkynes has been established under the irradiation of visible light in the presence of an organic dye. This transformation provides efficient access to highly functionalized pyrroles in good yields and has been applied to the formal synthesis of an inhibitor for HMG-CoA reductase.
- Xuan, Jun,Xia, Xu-Dong,Zeng, Ting-Ting,Feng, Zhu-Jia,Chen, Jia-Rong,Lu, Liang-Qiu,Xiao, Wen-Jing
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supporting information
p. 5653 - 5656
(2014/06/10)
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- A Site-Saturated Mutagenesis Study of Pentaerythritol Tetranitrate Reductase Reveals that Residues 181 and 184 Influence Ligand Binding, Stereochemistry and Reactivity
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We have conducted a site-specific saturation mutagenesis study of H181 and H184 of flavoprotein pentaerythritol tetranitrate reductase (PETN reductase) to probe the role of these residues in substrate binding and catalysis with a variety of α,β-unsaturated alkenes. Single mutations at these residues were sufficient to dramatically increase the enantiopurity of products formed by reduction of 2-phenyl-1-nitropropene. In addition, many mutants exhibited a switch in reactivity to predominantly catalyse nitro reduction, as opposed to C=C reduction. These mutants showed an enhancement in a minor side reaction and formed 2-phenylpropanal oxime from 2-phenyl-1-nitropropene. The multiple binding conformations of hydroxy substituted nitro-olefins in PETN reductase were examined by using both structural and catalytic techniques. These compounds were found to bind in both active and inhibitory complexes; this highlights the plasticity of the active site and the ability of the H181/H184 couple to coordinate with multiple functional groups. These properties demonstrate the potential to use PETN reductase as a scaffold in the development of industrially useful biocatalysts. Divergent evolution: A site-saturation study of PETN reductase was performed at conserved substrate binding residues H181 and H184. These residues were shown to dramatically alter the ratio of alkene versus nitro-group reduction in favour of oxime by-product formation, as summarised in the picture.
- Toogood, Helen S.,Fryszkowska, Anna,Hulley, Martyn,Sakuma, Michiyo,Mansell, David,Stephens, Gill M.,Gardiner, John M.,Scrutton, Nigel S.
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scheme or table
p. 738 - 749
(2012/02/01)
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- Dynamic path bifurcation in the Beckmann reaction: Support from kinetic analyses
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The reactions of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles when the migrating groups have reasonable stability as cations. The reactions of oxime sulfonates of 1-substituted-phenyl-2-propanone derivatives (7-X) and related substrates (8-X, 9a-X) in aqueous CH3CN gave both rearrangement products (amides) and fragmentation products (alcohols), the ratio of which depends on the system; the reactions of 7-X gave amides predominantly, whereas 9a-X yielded alcohols as the major product. The logk-logk plots between the systems gave excellent linear correlations with slopes of near unity. The results support the occurrence of path bifurcation after the rate-determining TS of the Beckmann rearrangement/fragmentation reaction, which has previously been proposed on the basis of molecular dynamics simulations. It was concluded that path-bifurcation phenomenon could be more common than thought and that a reactivity-selectivity argument based on the traditional TS theory may not always be applicable even to a well-known textbook organic reaction.
- Yamamoto, Yutaro,Hasegawa, Hiroto,Yamataka, Hiroshi
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experimental part
p. 4652 - 4660
(2011/07/29)
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- The flavoprotein-catalyzed reduction of aliphatic nitro-compounds represents a biocatalytic equivalent to the Nef-reaction
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The bioreduction of aliphatic sec-nitro compounds catalyzed by purified flavoproteins from the old-yellow-enzyme family unexpectedly furnished the corresponding carbonyl compounds instead of the expected amines and thus represents a biocatalytic equivalent to the Nef-reaction. The pathway was shown to proceed via initial reduction of the nitro-group to yield the nitroso-derivative, which spontaneously tautomerized to yield the more stable oxime, which was enzymatically reduced in a second step to furnish a hydrolytically unstable imine-species, which spontaneously hydrolyzed to finally give a carbonyl compound and ammonia.
- Durchschein, Katharina,Ferreira-Da Silva, Bianca,Wallner, Silvia,MacHeroux, Peter,Kroutil, Wolfgang,Glueck, Silvia Maria,Faber, Kurt
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supporting information; experimental part
p. 616 - 619
(2010/09/05)
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- Ketonitrones via cope-type hydroamination of allenes
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The synthesis of ketonitrones from W-alkylhydroxylamines and monosubstituted allenes is accomplished via a Cope-type hydroamination reaction in moderate to good yields. Allenes also undergo a similar reaction with aqueous hydroxylamine to give oximes in e
- Moran, Joseph,Pfeiffer, Jennifer Y.,Gorelsky, Serge I.,Beauchemin, Andre M.
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supporting information; experimental part
p. 1895 - 1898
(2009/09/08)
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- Intermolecular Cope-type hydroamination of alkenes and alkynes using hydroxylamines
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The development of the Cope-type hydroamination as a method for the metal- and acid-free intermolecular hydroamination of hydroxylamines with alkenes and alkynes is described. Aqueous hydroxylamine reacts efficiently with alkynes in a Markovnikov fashion to give oximes and with strained alkenes to give N-alkylhydroxylamines, while unstrained alkenes are more challenging. N-Alkylhydroxy-lamines also display similar reactivity with strained alkenes and give modest to good yields with vinylarenes. Electron-rich vinylarenes lead to branched products while electron-deficient vinylarenes give linear products. A beneficial additive effect is observed with sodium cyanoborohydride, the extent of which is dependent on the structure of the hydroxylamine. The reaction conditions are found to be compatible with common protecting groups, free OH and NH bonds, as well as bromoarenes. Both experimental and theoretical results suggest the proton transfer step of the N-oxide intermediate is of vital importance in the intermolecular reactions of alkenes. Details are disclosed concerning optimization, reaction scope, limitations, and theoretical analysis by DFT, which includes a detailed molecular orbital description for the concerted hydroamination process and an exhaustive set of calculated potential energy surfaces for the reactions of various alkenes, alkynes, and hydroxylamines.
- Moran, Joseph,Gorelsky, Serge I.,Dimitrijevic, Elena,Lebrun, Marie-Eve,Bedard, Anne-Catherine,Seguin, Catherine,Beauchemin, Andre M.
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supporting information; scheme or table
p. 17893 - 17906
(2009/07/18)
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- Intermolecular cope-type hydroamination of alkenes and alkynes
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(Chemical Equation Presented) Keep it simple! Intermolecular hydroamination can be achieved simply upon heating alkynes and alkenes with aqueous hydroxylamine. Alkynes react to afford oximes in good to excellent yields, and the formation of Markovnikov products is favored. A mechanism involving Cope-type hydroamination followed by bimolecular proton transfer is suggested and supported by DFT studies.
- Beauchemin, Andre M.,Moran, Joseph,Lebrun, Marie-Eve,Seguin, Catherine,Dimitrijevic, Elena,Zhang, Lili,Gorelsky, Serge I.
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p. 1410 - 1413
(2008/12/23)
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- Dioxime oxalates; new iminyl radical precursors for syntheses of N-heterocycles
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Symmetrical and unsymmetrical dioxime oxalates were prepared by treatment of oximes with oxalyl chloride. UV photolysis of these precursors was found to be an atom-efficient way of generating iminyl radicals. The process was most efficient for dioxime oxalates having aryl substituents attached to their C{double bond, long}N bonds. The method was useful for EPR spectroscopic study of iminyl and iminoxyl radicals. Photolyses in toluene solution, of dioxime oxalates containing alkenyl acceptor groups, yielded unsaturated iminyl radicals that ring closed to afford 3,4-dihydro-2H-pyrroles in good yields. Dioxime oxalates with biphenyl substituents also released iminyl radicals that ring closed onto the aromatic acceptor groups and, in acetonitrile solution, this approach provided a useful and atom-efficient method of making substituted phenanthridines.
- Portela-Cubillo, Fernando,Lymer, James,Scanlan, Eoin M.,Scott, Jackie S.,Walton, John C.
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supporting information; experimental part
p. 11908 - 11916
(2009/04/06)
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- A clean conversion of carbonyl compounds to oximes using silica gel supported hydroxylamine hydrochloride
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The efficient condensation of carbonyl compounds with hydroxylamine hydrochloride under solvent free conditions is described.
- Kiasat, Ali Reza,Kazemi, Foad,Nourbakhsh, Kazem
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p. 1193 - 1196
(2007/10/03)
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- Mono-deoxygenation of nitroalkanes, nitrones, and heterocyclic N-oxides by hexamethyldisilane through 1,2-elimination: Concept of 'counterattack reagent'
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Transformation of secondary nitroalkanes to ketoximes was achieved in 40-73% yields by treatment of the corresponding nitronate anions with hexamethyldisilane. In this new mono-deoxygenation process, hexamethyldisilane acted as a 'counterattack reagent'. The conversion of nitrones to imines was also achieved in 82-88% yields by use of trimethylsilyllithium. Similarly, heterocyclic N-oxides were converted to the corresponding N-heterocycles in 73-86% yields. These deoxygenation processes presumably involve a 1,2-elimination.
- Hwu, Jih Ru,Tseng, Wen Nan,Patel, Himatkumar V.,Wong, Fong Fuh,Horng, Den-Nan,Liaw, Ben Ruey,Lung Ching, Lin
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p. 2211 - 2218
(2007/10/03)
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- Action d'un Tetrafluoroborate d'Oxaziridinium sur les Amines et les Imines
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The Oxaziridinium salt 1 derived from dihydroisoquinolin is an oxygen transfer reagent to primary amines leading to nitrosoderivatives (if R = Alkyl) or nitro compounds (if R = Aryl), to tertiary amines leading to N-oxides, and to secondary amines and imines leading to the corresponding nitrone.
- Hanquet, Gilles,Lusinchi, Xavier
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p. 12185 - 12200
(2007/10/02)
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- Reduction of conjugated nitroalkenes with zinc borohydride. A mild method for converting monosubstituted nitroalkenes to nitroalkanes and disubstituted ones to oximes
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Mono-β-substituted conjugated nitroalkenes are readily reduced by zinc borohydride in 1,2-dimethoxyethane to the corresponding nitroalkanes, whereas the disubstituted ones furnish the corresponding oximes in excellent yields.
- Ranu,Chakraborty
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p. 5317 - 5322
(2007/10/02)
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- Cathodic Reduction of 1-Nitroalkenes to Oximes and Primary Amines
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1-Nitroalkenes are reduced in high yields at -0.3 to -0.5 V (vs.SCE) at a mercury or graphite cathode to oximes.At higher cathodic reduction potentials (-1.1 V) primary amines are selectively obtained in fair yields.Nitroalkadienes are selectively reduced at the double bond conjugated with the nitro group to either the oxime or amine.Key Words: Electrochemistry / 1-Nitroalkenes, reduction of / Oximes / Amines
- Wessling, Michael,Schaefer, Hans J.
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p. 2303 - 2306
(2007/10/02)
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- Highly Selective Reduction of Conjugated Nitroalkenes with Zinc Borohydride in DME
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Zinc borohydride in 1,2-dimethoxyethane reduces α-substituted conjugated nitroalkenes to the corresponding oximes and non-α-substituted ones to the corresponding nitroalkanes in excellent yields.
- Ranu, Brindaban C.,Chakraborty, Rupak
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p. 3579 - 3582
(2007/10/02)
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- The Palladium Assisted Transfer Reduction of α,β-Unsaturated Nitroalkenes to Oximes Using Ammonium Formate
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α,β-Unsaturated nitroalkenes are readily reduced to the corresponding oximes in good yields using ammonium formate in the presence of palladium.The reactions occur rapidly at room temperature in a solvent system of methanol and tetrahydrofuran.
- Kabalka, George W.,Pace, R. David,Wadgaonkar, P.P.
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p. 2453 - 2458
(2007/10/02)
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- THE PALLADIUM ASSISTED TRANSFER REDUCTION OF α,β-UNSATURATED NITROALKENES USING SODIUM HYPOPHOSPHITE: A SYNTHESIS OF OXIMES
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α,β-Unsaturated nitroalkenes are readily reduced by sodium hypophosphite to the corresponding oximes in the presence of palladium.
- Varma, Rajender S.,Varma, Manju,Kabalka, George W.
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- Photochemical and Chemical Reduction of Nitroalkenes Using Viologens as an Electron Phase-Transfer Catalyst
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An amphiphilic electron acceptor, i.e., N,N'-dioctyl-4,4'-bipyridinium, was used as an electron carrier between water-oil two phase, in which nitroalkenes in organic phase were readily reduced to the corresponding oximes and/or carbonyl compounds.
- Tomioka, Hideo,Ueda, Koichi,Ohi, Hirofumi,Izawa, Yasuji
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p. 1359 - 1362
(2007/10/02)
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- A FACILE KETOXIME PREPARATION VIA THE REDUCTION OF Αa,β-UNSATURATED NITROALKENES USING SODIUM STANNITE
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α,β-Unsaturated nitroalkenes are readily reduced by sodium stannite to ketoximes at room temperature.
- Varma, Rajender S.,Varma, Manju,Kabalka, George W.
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p. 6013 - 6014
(2007/10/02)
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- REDUCTIVE CONVERSION OF NITRO ALKENES TO KETONES AND/OR OXIMES IN AN AQUEOUS HClO4-CH2Cl2-DIOXANE-(Pb) SYSTEM
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Electrochemical and chemical reduction of nitro alkenes in an aqueous HClO4-CH2Cl2-dioxane-(Pb) system afforded ketones and oximes in good yields, each of which can be obtained selectively by treating with either aqueous formaldehyde or hydroxylamine as a proper workup process, respectively.
- Torii, Sigeru,Tanaka, Hideo,Katoh, Tetsuo
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p. 607 - 610
(2007/10/02)
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- Alkylwanderungen bei Sextettumlagerungen
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The migration aptitude of alkyl groups in the Beckmann-, the Criegee-, and the isonitrile-nitrile rearrangements were investigated.The relative rearrangement rates of substituted benzyl groups are an expression of the charge on the migrating carbon at transition state.From the relative rates of migration of exo- and endo-2-norbornyl groups the geometrical changes at the migrating carbon is estimated.Finally, the different influence of α-branching in the migrating group is discussed for these and some other rearrangements.
- Langhals, Heinz,Range, Guenter,Wistuba, Eckehardt,Ruechardt, Christoph
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p. 3813 - 3830
(2007/10/02)
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- The structure of nitrones derived from amphetamines
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The nitrones obtained by mercuric oxide oxidation of N hydroxy N n propylamphetamine and N ethyl N hydroxyamphetamine were identified. The major in vitro metabolic product of fenfluramine is shown by a nuclear magnetic resonance study to be α methyl N [1 (m trifluoromethylbenzyl)ethyl]nitrone and not the isomer as claimed previously.
- Beckett,Coutts,Ogunbona
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p. 312 - 316
(2007/10/05)
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