Journal articles: 'Oxime Chemistry'

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Dhuguru, Jyothi, Eugene Zviagin, and Rachid Skouta. "FDA-Approved Oximes and Their Significance in Medicinal Chemistry." Pharmaceuticals 15, no. 1 (January 4, 2022): 66. http://dx.doi.org/10.3390/ph15010066.

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Despite the scientific advancements, organophosphate (OP) poisoning continues to be a major threat to humans, accounting for nearly one million poisoning cases every year leading to at least 20,000 deaths worldwide. Oximes represent the most important class in medicinal chemistry, renowned for their widespread applications as OP antidotes, drugs and intermediates for the synthesis of several pharmacological derivatives. Common oxime based reactivators or nerve antidotes include pralidoxime, obidoxime, HI-6, trimedoxime and methoxime, among which pralidoxime is the only FDA-approved drug. Cephalosporins are β-lactam based antibiotics and serve as widely acclaimed tools in fighting bacterial infections. Oxime based cephalosporins have emerged as an important class of drugs with improved efficacy and a broad spectrum of anti-microbial activity against Gram-positive and Gram-negative pathogens. Among the several oxime based derivatives, cefuroxime, ceftizoxime, cefpodoxime and cefmenoxime are the FDA approved oxime-based antibiotics. Given the pharmacological significance of oximes, in the present paper, we put together all the FDA-approved oximes and discuss their mechanism of action, pharmacokinetics and synthesis.

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Ahmed, Sarbast M., Faiq H. S. Hussain, and Paolo Quadrelli. "9-Anthraldehyde oxime: a synthetic tool for variable applications." Monatshefte für Chemie - Chemical Monthly 151, no. 11 (November 2020): 1643–58. http://dx.doi.org/10.1007/s00706-020-02695-2.

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Abstract Oximes are one of the most important and prolific functional groups in organic chemistry; among them, 9-anthraldehyde oxime represents a valuable example both from the preparative side and the synthetic applications. There are many strategies to prepare 9-anthraldehyde oxime from different functional groups that were summarized in the present review, focusing on the most recent and innovative. The main synthetic applications of 9-anthraldehyde oxime are presented and thoroughly discussed, focusing on the most recent and innovative synthetic strategies. Graphic abstract

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Diedrichs, Nicole, Ralf Krelaus, Ina Gedrath, and Bernhard Westermann. "Kinetic resolution of oxime esters with lipases synthesis of enantiomerically enriched building blocks with quaternary carbon centers and formal total synthesis of perhydro histrionicotoxin." Canadian Journal of Chemistry 80, no. 6 (June 1, 2002): 686–91. http://dx.doi.org/10.1139/v02-097.

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Enantiomerically enriched oximes bearing stereogenic quaternary carbon centers can be obtained by lipase-catalyzed kinetic resolution of oxime esters. Substrate specificity, solvent effects, and the use of different lipases are discussed. Kinetic resolution of butyrylated oximes by lipase PS in the presence of n-butanol gave the best ee-values of both the saponified oxime and the residual oxime ester. Subsequent stereospecific Beckmann rearrangement of an enantiomerically enriched oxime provided lactams, which could be employed for the synthesis of optically active perhydro histrionicotoxin.Key words: oxime, lipase, kinetic resolution, Beckmann rearrangement, perhydro histrionicotoxin.

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Low, John Nicolson, James Lewis Wardell, Cristiane Franca Da Costa, Marcus Vicinius Nora Souza, and Ligia Rebelo Gomes. "Structural study of three heteroaryl oximes, heteroaryl-N=OH: Compounds forming strong C3 molecular chains." European Journal of Chemistry 9, no. 3 (September 30, 2018): 151–60. http://dx.doi.org/10.5155/eurjchem.9.3.151-160.1734.

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In order to further investigate the structural chemistry of oximes and to further establish the main structural arrangements adopted, we have determined the crystal structure of and carried out Hirshfeld surface calculations on three heteroaryl oximes, namely (Z)-thiophene-2-carbaldehyde oxime (1), (Z)-1H-pyrrole-2 carbaldehyde oxime (2) and (Z)-5-nitrofuran-2-carbaldehyde oxime (3). As confirmed by both techniques, the major intermolecular interactions in each compound are classical N—H···O hydrogen bonds, which link the molecules into C3 chains. Such an arrangement has been previous reported as an important aggregation mode for oximes. Secondary interactions, C—H···π and C—H···O interactions, in compounds 1 and 2, and interactions involving the nitro group oxygen atoms in compound 3 link the chains into three dimensional arrays.

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Kubicki, Maciej, Teresa Borowiak, and Wiesław Z. Antkowiak. "Hydrogen Bonds in "Carboxyoximes": the Case of Bomane Derivatives." Zeitschrift für Naturforschung B 55, no. 8 (August 1, 2000): 677–84. http://dx.doi.org/10.1515/znb-2000-0802.

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Abstract The tendency of forming mixed carboxyl-to-oxime hydrogen bonds was tested on the series of bornane derivatives: one with the acid function only (bornane-2-endo-carboxylic acid), one with the oxime function (2,2′-diethylthiobomane-3-oxime), and one with both oxime and carboxylic functions (bornane-2-oxime-3-endo-carboxylic acid). The crystal structures of these compounds were determined by means of X-ray diffraction. In bornane-2-endo-carboxylic acid and 2,2′-diethylthiobornane-3-oxime 'homogenic' hydrogen bonds were found, and these hydrogen bonds close eight-and six-membered rings, respectively. By contrast, in bornane-2-oxime-3-endo-carboxylic acid 'heterogenic' hydrogen bonds between carboxylic and oxime bonds were found. This carboxylic-oxime, or 'carboxyoxime' system is almost always present in compounds which have both oxime and carboxylic groups; therefore it can be regarded as an element of supramolecular structures (synthon). The presence of such synthons can break the tendency of carboxylic acids and oximes towards crystallizing in centrosymmetric structures.

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Gulla, Mahendra, Lars Bierer, Stefan Schmidt, Leo Redcliffe, and Volker Jäger. "Bromocyclization of Unsaturated Oximes. Synthesis of Five-Membered Cyclic Nitrones (Pyrroline N-Oxides)." Zeitschrift für Naturforschung B 61, no. 4 (April 1, 2006): 471–85. http://dx.doi.org/10.1515/znb-2006-0414.

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The cyclization of a ribose-derived pentenose oxime with various halogen electrophiles showed bromine to be the most effective reagent, leading to 80% of L-lyxo/D-ribo-pyrroline N-oxides in an 84:16 diastereomeric ratio. In order to explore the scope of this facile process, several other γ,δ - unsaturated oximes were submitted to this reaction. Depending on the substitution pattern, 23 - 87%, yields of pyrroline N-oxides of were registered. With α-allyl-β -ketoester oximes the alkoxycarbonyl group proved a similar (ethoxy) or even better (t-butoxy) trapping nucleophile, leading preferentially to the corresponding bromolactone oxime. - With 2,2-dimethyl-3-butene aldoxime, the corresponding 3-bromopyrroline N-oxide was formed, due to a formal, unusual N-endo cyclization to the chain terminus. This was exploited for a new access to six-membered nitrones from a γ,δ -pentene aldoxime, with addition of Br/OH to the C=C of the 4-pentenal first, and oximation/cyclization following then

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Yamamoto, Hitoshi, Toshikage Asakura, Yuichi Nishimae, Akira Matsumoto, Junichi Tanabe, Jean-Luc Birbaum, Peter Murer, Tobias Hinterman, and Masaki Ohwa. "Oxime Sulfonate Chemistry for Advanced Microlithography." Journal of Photopolymer Science and Technology 20, no. 5 (2007): 637–42. http://dx.doi.org/10.2494/photopolymer.20.637.

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8

Grover, Gregory N., Jonathan Lam, Thi H. Nguyen, Tatiana Segura, and Heather D. Maynard. "Biocompatible Hydrogels by Oxime Click Chemistry." Biomacromolecules 13, no. 10 (September 12, 2012): 3013–17. http://dx.doi.org/10.1021/bm301346e.

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9

Canário, Catarina, Mariana Matias, Vanessa Brito, Adriana O. Santos, Amílcar Falcão, Samuel Silvestre, and Gilberto Alves. "New Estrone Oxime Derivatives: Synthesis, Cytotoxic Evaluation and Docking Studies." Molecules 26, no. 9 (May 4, 2021): 2687. http://dx.doi.org/10.3390/molecules26092687.

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The interest in the introduction of the oxime group in molecules aiming to improve their biological effects is increasing. This work aimed to develop new steroidal oximes of the estrane series with potential antitumor interest. For this, several oximes were synthesized by reaction of hydroxylamine with the 17-ketone of estrone derivatives. Then, their cytotoxicity was evaluated in six cell lines. An estrogenicity assay, a cell cycle distribution analysis and a fluorescence microscopy study with Hoechst 3358 staining were performed with the most promising compound. In addition, molecular docking studies against estrogen receptor α, steroid sulfatase, 17β-hydroxysteroid dehydrogenase type 1 and β-tubulin were also accomplished. The 2-nitroestrone oxime showed higher cytotoxicity than the parent compound on MCF-7 cancer cells. Furthermore, the oximes bearing halogen groups in A-ring evidenced selectivity for HepaRG cells. Remarkably, the Δ9,11-estrone oxime was the most cytotoxic and arrested LNCaP cells in the G2/M phase. Fluorescence microscopy studies showed the presence of condensed DNA typical of prophase and condensed and fragmented nuclei characteristic of apoptosis. However, this oxime promoted the proliferation of T47-D cells. Interestingly, molecular docking studies estimated a strong interaction between Δ9,11-estrone oxime and estrogen receptor α and β-tubulin, which may account for the described effects.

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10

Plater, M. John, William TA Harrison, and Ross Killah. "Potential photoacid generators based on oxime sulfonates." Journal of Chemical Research 43, no. 1-2 (January 2019): 26–33. http://dx.doi.org/10.1177/1747519819831829.

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The bis-oxime of acenaphthenequinone and the mono-oxime of benzil have been sulfonated by reaction with 4-methylbenzenesulfonyl chloride and propylsulfonyl chloride. The four sulfonated oximes were characterised by X-ray single-crystal structure determinations. Some photochemical decompositions were studied using a 6-W 254-nm immersion well lamp in dichloromethane. The 4-methylbenzenesulfonate bis-oxime of acenaphthenequinone and the 4-methylbenzenesulfonate mono-oxime of benzil both give 4-methylbenzenesulfonic acid upon irradiation but not 4-methylbenzenesulfinic acid. Fragmentation pathways are discussed. The possible use of these compounds as photoacid generators in polymer resists and the role of secondary reactions to liberate acid is discussed.

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11

Bermejo, Elena, Alfonso Castiñeiras, and Douglas X. West. "Structural Study of an N(4)-Substituted Thiosemicarbazone Prepared from 1-Phenyl-1,2-propanedione-2-oxime, and of a Related Nickel(II) Complex." Zeitschrift für Naturforschung B 56, no. 4-5 (May 1, 2001): 369–74. http://dx.doi.org/10.1515/znb-2001-4-508.

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Abstract 1-Phenyl-1,2-propanedione-2-oxime reacts with 3-piperidylthiosemicarbazide and 3-hexamethyleneiminylthiosemicarbazide to give the respective 1-phenyl-1,2-propanedione-1-thiosemicarbazone-2-oximes, HPopip and HPohexim. The crystal structure of HPopip shows the oxime and thiosemicarbazone moieties in a conformation single-trans respect to carbon-carbon. A six-coordinate nickel(II) complex, [Ni(Pohexim)2], has two monoanionic (through loss of a proton from the thiosemicarbazone function) oxime-thiosemicarbazone ligands coordinated in a meridonal arrangement via the oxime nitrogen, the thiosemicarbazone imine nitrogen and the thiolato sulfur atoms. The bond distances to nickel are shorter than found for other six-coordinate complexes with monoanionic tridentate thiosemicarbazone ligands.

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12

Arthur-Santiago, Margarita A., Rosa María Oliart-Ros, María G. Sánchez-Otero, and Gerardo Valerio-Alfaro. "Mechanochemo-enzymatic Synthesis of Aromatic Aldehyde Oxime Esters." Natural Product Communications 13, no. 7 (July 2018): 1934578X1801300. http://dx.doi.org/10.1177/1934578x1801300723.

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The synthesis of aromatic aldehyde oxime esters (considered fragrances, antifungal and antimicrobial compounds) was achieved by two reactions which combine the advantage of green chemistry and biocatalysis. In the first step, the mechanochemical oxime synthesis by means of grindstone milling of six solid aromatic aldehydes and hydroxylamine hydrochloride in the presence of FlorisilR, as the best support, yielded the aromatic aldehyde oximes 1–6 with high purity and good yields. In the second step the lipase catalyzed acetylation reaction at 40°C for three days of those oximes with vinyl and isopropenyl acetates as acyl donor substrates and ethyl acetate as the solvent, yielded the aromatic aldehyde oxime esters. With Candida antarctica lipase (Novozyme 435), the conversions of oximes 1–6 into their esters were ≥ 99% according to the 1H NMR results and it was the best biocatalyst compared with others such as Candida rugosa (CRL), porcine pancreas lipase and the recombinant lipase LipMatCCR11 from the thermophilic strain Geobacillus thermoleovorans CCR11 cloned and expressed in Escherichia coli BL21 (DE3), all of which showed lower yields.

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13

Çil, Erol, Mustafa Arslan, and Ahmet Orhan Görgülü. "Synthesis and characterization of alkyl- and acyl-substituted oximephosphazenes." Canadian Journal of Chemistry 83, no. 12 (December 1, 2005): 2039–45. http://dx.doi.org/10.1139/v05-223.

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Two oximecyclophosphazenes were prepared from the hexakis(4-formylphenoxy)cyclotriphosphazene (2) and hexakis(4-acetylphenoxy)cyclotriphosphazene (8). The reactions of these oximes with ethyl bromide, allyl bromide, propanoyl chloride, and acriloyl chloride were studied. Hexasubstituted compounds were obtained from the reactions of hexakis{4-[(hydroxyimino)methyl]phenoxy}cyclotriphosphazene (3) with ethyl bromide (4), allyl bromide (5), and propanoyl chloride (6), however, the oxime groups on 3 rearranged to nitrile (7) in the reaction of 3 with acriloyl chloride. Hexasubstituted compounds were also obtained from the reactions of hexakis{4-[(1)-N-hydroxyethaneimidoyl]phenoxy}cyclotriphosphazene (9) with allyl bromide (11) and propanoyl chloride (12). Tetra- and penta-substituted products were obtained from the reactions of 9 with ethyl bromide (10) and acriloyl chloride (13), respectively. All products were generally obtained in high yields. The structures of the compounds were defined by elemental analysis, IR, 1H, 13C, and 31P NMR spectroscopy. Key words: hexachlorocyclotriphosphazene, phosphazene, oxime, oxime derivatives, oximephosphazenes.

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14

Foretić, Blaženka, Vladimir Damjanović, Robert Vianello, and Igor Picek. "Novel Insights into the Thioesterolytic Activity of N-Substituted Pyridinium-4-oximes." Molecules 25, no. 10 (May 21, 2020): 2385. http://dx.doi.org/10.3390/molecules25102385.

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The pyridinium oximes are known esterolytic agents, usually classified in the literature as catalysts, which mimic the catalytic mode of hydrolases. Herein, we combined kinetic and computational studies of the pyridinium-4-oxime-mediated acetylthiocholine (AcSCh+) hydrolysis to provide novel insights into their potential catalytic activity. The N-methyl- and N-benzylpyridinium-4-oximes have been tested as oximolytic agents toward the AcSCh+, while the newly synthesized O-acetyl-N-methylpyridinium-4-oxime iodide was employed for studying the consecutive hydrolytic reaction. The relevance of the AcSCh+ hydrolysis as a competitive reaction to AcSCh+ oximolysis was also investigated. The reactions were independently studied spectrophotometrically and rate constants, koxime, kw and kOH, were evaluated over a convenient pH-range at I = 0.1 M and 25 °C. The catalytic action of pyridinium-4-oximes comprises two successive stages, acetylation (oximolysis) and deacetylation stage (pyridinium-4-oxime-ester hydrolysis), the latter being crucial for understanding the whole catalytic cycle. The complete mechanism is presented by the free energy reaction profiles obtained with (CPCM)/M06–2X/6–311++G(2df,2pd)//(CPCM)/M06–2X/6–31+G(d) computational model. The comparison of the observed rates of AcSCh+ oximolytic cleavage and both competitive AcSCh+ and consecutive pyridinium-4-oxime-ester hydrolytic cleavage revealed that the pyridinium-4-oximes cannot be classified as non-enzyme catalyst of the AcSCh+ hydrolysis but as the very effective esterolytic agents.

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15

Oh, Ilwhan, and Rich I. Masel. "Electrochemical Organophosphate Sensor Based on Oxime Chemistry." Electrochemical and Solid-State Letters 10, no. 2 (2007): J19. http://dx.doi.org/10.1149/1.2400206.

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Song, J. H., S. M. Bae, E. J. Lee, J. H. Cho, and D. I. Jung. "Formation of Benzodiazepines and Pyrazinylquinoxalines from Aromatic and Heteroaromatic Ketones via Deoximation." Asian Journal of Chemistry 32, no. 7 (2020): 1676–80. http://dx.doi.org/10.14233/ajchem.2020.22639.

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The report stated that the treatment of o-phenylenediamine with acetone dicarboxylic acid, acetone and acetophenone afforded 2,4,4-trimethyl-3H-5-hydro-1,5-benzodiazepine. However, direct reactions of o-phenylenediamine with oximes (acetone oxime, acetophenone oxime, and benzophenone oxime) as ketone equivalents did not occur. In the course of present investigations, it is found that dichloroamine-T can be an efficient reagent for the conversion of oximes into the corresponding carbonyl compounds. As a part of a research program related to the synthetic study of pharmacologically interesting benzodiazepine compounds, herein the synthesis of 1H-1,5-benzodiazepine derivatives from heteroaromatic ketones and acetone equivalents obtained using dichloroamine-T. On the other hand, when diamine (1,2-phenylene diamine or 1,2-naphthalene diamine) with heterocyclic ketone (acetyl pyridine or acetyl pyrazines) in the presenece of conc. HCl and SiO2 was refluxed, quinoxaline derivatives as yellow crystalline solids were isolated in high yields

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Collins, Joe, Zeyun Xiao, Andrea Espinosa-Gomez, Brett P. Fors, and Luke A. Connal. "Extremely rapid and versatile synthesis of high molecular weight step growth polymers via oxime click chemistry." Polymer Chemistry 7, no. 14 (2016): 2581–88. http://dx.doi.org/10.1039/c6py00372a.

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18

de Lijser, HJ Peter, Jason S. Kim, Suzanne M. McGrorty, and Erin M. Ulloa. "Substituent effects in oxime radical cations. 1. Photosensitized reactions of acetophenone oximes." Canadian Journal of Chemistry 81, no. 6 (June 1, 2003): 575–85. http://dx.doi.org/10.1139/v03-052.

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A variety of ortho-, meta-, and para-substituted (-H, -F, -Cl, -CF3, -CN (meta and para only), -CH3, -OCH3, and -NO2) acetophenone oximes were synthesized and studied using laser flash photolysis (LFP) and steady-state photolysis experiments in acetonitrile with chloranil as the photosensitizer. In addition, semi-empirical (AM1) calculations were performed on the neutral species, the radical cations, and the corresponding iminoxyl radicals. The data was analyzed in terms of the electrochemical peak potentials of the oximes, the quenching rates of triplet chloranil (LFP), the calculated ionization potentials, and the measured conversions of the oximes in the steady-state photolysis experiments. Photolysis of the oximes in the presence of chloranil results in the formation of the chloranil radical anion, which reacts rapidly with the oxime radical cation to form the semiquinone radical and an iminoxyl radical. Evidence for the formation of the chloranil radical anion and the semiquinone radical was obtained from LFP studies. The measured quenching rates from the LFP studies represent the rates of electron transfer from the oximes to triplet chloranil. This data was correlated to various radical and polar substituent constants. The Hammett studies suggest that steric, polar, and radical effects are important for ortho-substituted acetophenone oximes, polar effects are important for para-substituted oximes, and radical stabilization is more important than polar effects for the meta-substituted substrates. The calculated ionization potentials of the oximes show an excellent correlation with the measured quenching rates supporting the electron transfer pathway. On the basis of calculated charge densities, we conclude that the measured substituent effects are transition state effects rather than ground state effects. At this point all of the available data suggests that the conversion of the oximes is controlled by two energetically opposing reactions, namely oxidation of the neutral oxime, which is favorable for oximes with electron-donating substituents, and deprotonation of the oxime radical cation, which is favorable for oximes with electron-withdrawing substituents. The overall result is a reaction with little selectivity as far as substituent effects are concerned.Key words: oxime, radical cation, iminoxyl radical, electron transfer, substituent effect.

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Li, Huimin, Lihao Liao, and Xiaodan Zhao. "Organoselenium-Catalyzed Aza-Wacker Reactions: Efficient Access to Isoquinolinium Imides and an Isoquinoline N-Oxide." Synlett 30, no. 14 (June 28, 2019): 1688–92. http://dx.doi.org/10.1055/s-0039-1690103.

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An efficient approach for the organoselenium-catalyzed aza-Wacker reaction of olefinic hydrazones and an oxime to form isoquinolinium imides and an isoquinoline N-oxide is developed. This transformation involves a direct intramolecular C–H amination using hydrazones and an oxime as imine-type nitrogen sources. This work not only provides a new approach for the construction of isoquinoline derivatives, but also expands the scope of nitrogen sources in electrophilic selenium catalysis.

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20

A S, Manjunatha, Anu Sukhdev, Putta Swamy, and Shashi Dhara T S. "Exploration of Ruthenium (III) Chloride catalysis on oxidative conversion of aryloximes to arylaldehydes with bromamine-B: A kinetic and mechanistic approach." Journal of University of Shanghai for Science and Technology 23, no. 05 (May 17, 2021): 240–61. http://dx.doi.org/10.51201/jusst/21/05142.

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Conversion of aryloximes to corresponding arylaldehydes is an important oxidative transformation in synthetic chemistry. In the course of this research, optimum conditions for the facile oxidation of benzaldehyde oxime and p-substituted benzaldehyde oximes viz., p-hydroxybenzaldehyde oxime, p-methoxy benzaldehyde oxime, p-bromobenzaldehyde oxime and p-nitrobenzaldehyde oxime (aryloximes) with bromamine–B (BAB) catalyzed by ruthenium (III) chloride (RuCl3) in perchloric acid (HClO4) medium have been kinetically investigated at 303 K. All the five aryloximes follow identical kinetics with a first-order dependence of rate on [BAB]o, fractional-order each on [aryloximes]o and [RuCl3], and an inverse fractional-order on [H+]. Activation parameters have been evaluated. Oxidation products were characterized by spectral analysis. Under the identical set of experimental conditions, the kinetics of catalyzed reactions has been compared with uncatalyzed reactions and found that the catalyzed reactions are 4–6 folds faster. Isokinetic temperature is found to be 338 K. The catalytic constants (Kc) have been calculated at different temperatures and the values of activation parameters with respect to the catalyst have been evaluated. Spectroscopic evidence for the formation of 1:1 complex between BAB and RuCl3 has been obtained. The observed results have been explained by a plausible mechanism and the related rate law has been deduced. The present method offers many advantages including high conversion, short reaction times and the involvement of non-toxic reagents.

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Andrýs, Rudolf, Aneta Klusoňová, Miroslav Lísa, and Jana Žd'árová Karasová. "Encapsulation of oxime acetylcholinesterase reactivators: influence of physiological conditions on the stability of oxime-cucurbit[7]uril complexes." New Journal of Chemistry 44, no. 34 (2020): 14367–72. http://dx.doi.org/10.1039/d0nj03102j.

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The influence of physiological conditions on the host–guest chemistry of oxime acetylcholinesterase reactivators with cucurbit[7]urile was investigated to increase their effectiveness for the treatment of organophosphate intoxication.

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Krylov, Igor B., Stanislav A. Paveliev, Alexander S. Budnikov, and Alexander O. Terent’ev. "Oxime radicals: generation, properties and application in organic synthesis." Beilstein Journal of Organic Chemistry 16 (June 5, 2020): 1234–76. http://dx.doi.org/10.3762/bjoc.16.107.

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N-Oxyl radicals (compounds with an N–O• fragment) represent one of the richest families of stable and persistent organic radicals with applications ranging from catalysis of selective oxidation processes and mechanistic studies to production of polymers, energy storage, magnetic materials design and spectroscopic studies of biological objects. Compared to other N-oxyl radicals, oxime radicals (or iminoxyl radicals) have been underestimated for a long time as useful intermediates for organic synthesis, despite the fact that their precursors, oximes, are extremely widespread and easily available organic compounds. Furthermore, oxime radicals are structurally exceptional. In these radicals, the N–O• fragment is connected to an organic moiety by a double bond, whereas all other classes of N-oxyl radicals contain an R2N–O• fragment with two single C–N bonds. Although oxime radicals have been known since 1964, their broad synthetic potential was not recognized until the last decade, when numerous selective reactions of oxidative cyclization, functionalization, and coupling mediated by iminoxyl radicals were discovered. This review is focused on the synthetic methods based on iminoxyl radicals developed in the last ten years and also contains some selected data on previous works regarding generation, structure, stability, and spectral properties of these N-oxyl radicals. The reactions of oxime radicals are classified into intermolecular (oxidation by oxime radicals, oxidative C–O coupling) and intramolecular. The majority of works are devoted to intramolecular reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage.

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23

Palacios, Javier, Adrián Paredes, Marcelo A. Catalán, Chukwuemeka R. Nwokocha, and Fredi Cifuentes. "Novel Oxime Synthesized from a Natural Product of Senecio nutans SCh. Bip. (Asteraceae) Enhances Vascular Relaxation in Rats by an Endothelium-Independent Mechanism." Molecules 27, no. 10 (May 22, 2022): 3333. http://dx.doi.org/10.3390/molecules27103333.

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Senecio nutans Sch. Bip. and its constituents are reported to have antihypertensive effects. We isolated metabolite–1, a natural compound from S. nutans (4-hydroxy-3-(isopenten-2-yl)-acetophenone), and synthesized novel oxime – 1 (4-hydroxy-3-(isopenten-2-yl)-acetophenoxime) to evaluate their effect on vascular reactivity. Compounds were purified (metabolite–1) or synthetized (oxime–1) and characterized using IR and NMR spectroscopy and Heteronuclear Multiple Quantum Coherence (HMQC). Using pharmacological agents such as phenylephrine (PE) and KCl (enhancing contraction), acetylcholine (ACh), L-NAME (nitric oxide (NO) and endothelial function), Bay K8644-induced CaV1.2 channel (calcium channel modulator), and isolated aortic rings in an organ bath setup, the possible mechanisms of vascular action were determined. Pre-incubation of aortic rings with 10−5 M oxime–1 significantly (p < 0.001) decreased the contractile response to 30 mM KCl. EC50 to KCl significantly (p < 0.01) increased in the presence of oxime–1 (37.72 ± 2.10 mM) compared to that obtained under control conditions (22.37 ± 1.40 mM). Oxime–1 significantly reduced (p < 0.001) the contractile response to different concentrations of PE (10−7 to 10−5 M) by a mechanism that decreases Cav1.2-mediated Ca2+ influx from the extracellular space and reduces Ca2+ release from intracellular stores. At a submaximal concentration (10−5 M), oxime–1 caused a significant relaxation in rat aorta even without vascular endothelium or after pre-incubate the tissue with L-NAME. Oxime–1 decreases the contractile response to PE by blunting the release of Ca2+ from intracellular stores and blocking of Ca2+ influx by channels. Metabolite–1 reduces the contractile response to KCl, apparently by reducing the plasma membrane depolarization and Ca2+ influx from the extracellular space. These acetophenone derivates from S. nutans (metabolite–1 and oxime–1) cause vasorelaxation through pathways involving an increase of the endothelial NO generation or a higher bioavailability, further highlighting that structural modification of naturally occurring metabolites can enhance their intended pharmacological functions.

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Tudosie, Mihail S., Bogdan Patrinich, Andreea R. Negrea, and Cristina A. Secară. "New synthesized oximes active in nerve agents’ hazards." Romanian Journal of Military Medicine 120, no. 2 (August 2, 2017): 47–53. http://dx.doi.org/10.55453/rjmm.2017.120.2.7.

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Object: The aim of the study is to select the most active new imidazolium-quinuclidinumoxime, from some similar chemical compounds synthesized in our chemistry department, with sufficient efficacy to decrease the acute toxicity of neurotoxic organophosphates known as nerve agents. Method: The experimental study consist in vivo testing the antidotal efficacy of obidoxime and of selected imidazolium oximes synthesized in our chemistry department. Each oxime was included, by equimolar replacing the obidoxime, in an antidotal formula, which also contains atropine. The above mentioned formula containing atropine and obidoxime was used as reference. The protective ratio, defined as the ratio between the lethal median dose of the poisoned and treated study group and the median lethal dose (LD50) of the poisoned and untreated study groups was one of the used parameters in order to select a new active chemical structure in counteracting the neurotoxic organophosphorus compounds acute toxicity. Another studied parameter was the erythrocyte acetylcholinesterase value measured in whole blood 24 hours after exposure. Results: The protective ratio against an organophosphorus compound were the follow: obidoxime chloride: 2; 1,3- dimethyl-2-hydroxyethyl-imidazolyliodide: 1,75;3-oxime-[3-(2-hidroxyimino-methyl-1-imidazolyl-)- 2oxapropyl]quinuclidin-dichl-oride: 2,5; 1-methyl-quinuclidin-3-iodide: 1,5. The erythrocyte acetycholinesterase main values were the following: the unpoisoned and untreated study group:3,45 ±0,13mmol/dl; the poisoned and untreated study group: 0,89 ±0,09 mmol/dl; the poisoned and 3- oxime-[3-(2-hidroxyimino-methyl-1-imidazolyl-)-2oxapropyl]quinuclidindichloride treated study group:2,89 ±0,11 mmol/dl; the poisoned and obidoxime treated study group: 2,53±0,15 mmol/dl. Conclusions: 3-oxime-[3-(2-hidroxyimino-methyl-1-imidazolyl-)-2oxapropyl] quinuclidindichloride synthesized in our chemistry department, has shown a better protective ratio and a more prolonged surviving time than the reference (obidoxime). It has shown the best AChE reactivation of all the synthetized compounds. This compound can be a cheap and good option for replacing obidoxime in the antidotal formula active in nerve agent exposure.

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Surowiak, Alicja K., Stanisław Lochyński, and Daniel J. Strub. "Unsubstituted Oximes as Potential Therapeutic Agents." Symmetry 12, no. 4 (April 5, 2020): 575. http://dx.doi.org/10.3390/sym12040575.

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Oximes, which are highly bioactive molecules, have versatile uses in the medical sector and have been indicated to possess biological activity. Certain oximes exist in nature in plants and animals, but they are also obtained by chemical synthesis. Oximes are known for their anti-inflammatory, antimicrobial, antioxidant and anticancer activities. Moreover, they are therapeutic agents against organophosphate (OP) poisoning. Two oximes are already commonly used in therapy. Due to these abilities, new oxime compounds have been synthesized, and their biological activity has been verified. Often, modification of carbonyl compounds into oximes leads to increased activity. Nevertheless, in some cases, oxime activity is connected to the activity of the substrate. Recent works have revealed that new oxime compounds can demonstrate such functions and thus are considered to be potential drugs for pathogenic diseases, as adjuvant therapy in various types of cancer and inflammation and as potential next-generation drugs against OP poisoning.

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Surowiak, Alicja K., Stanisław Lochyński, and Daniel J. Strub. "Correction: Surowiak, A.K.; Lochyński, S.; Strub, D.J. Unsubstituted Oximes as Potential Therapeutic Agents. Symmetry 2020, 12, 575." Symmetry 12, no. 6 (June 12, 2020): 1006. http://dx.doi.org/10.3390/sym12061006.

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Oximes, which are highly bioactive molecules, have versatile uses in the medical sector and have been indicated to possess biological activity. Certain oximes exist in nature in plants and animals, but they are also obtained by chemical synthesis. Oximes are known for their anti-inflammatory, antimicrobial, antioxidant and anticancer activities. Moreover, they are therapeutic agents against organophosphate (OP) poisoning. Two oximes are already commonly used in therapy. Due to these abilities, new oxime compounds have been synthesized, and their biological activity has been verified. Often, modification of carbonyl compounds into oximes leads to increased activity. Nevertheless, in some cases, oxime activity is connected to the activity of the substrate. Recent works have revealed that new oxime compounds can demonstrate such functions and thus are considered to be potential drugs for pathogenic diseases, as adjuvant therapy in various types of cancer and inflammation and as potential next-generation drugs against OP poisoning.

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27

Renaudet, Olivier, and Jean-Louis Reymond. "Iterative Oxime Bond Chemistry Leads to Protease Inhibitors." Organic Letters 5, no. 24 (November 2003): 4693–96. http://dx.doi.org/10.1021/ol035867r.

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Sun, Baozhen, Shuang Liu, Mengru Zhang, Jinbo Zhao, and Qian Zhang. "Pd-Catalyzed carboannulation of γ,δ-alkenyl oximes: efficient access to 5-membered cyclic nitrones and dihydroazines." Organic Chemistry Frontiers 6, no. 3 (2019): 388–92. http://dx.doi.org/10.1039/c8qo01076e.

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Mehrez, Asma, Dalila Mtat, and Ridha Touati. "Microwave-Assisted Synthesis of Chiral Oxime Ethers." Letters in Organic Chemistry 16, no. 6 (April 23, 2019): 495–500. http://dx.doi.org/10.2174/1570178615666181106125853.

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An efficient and rapid synthesis of a new class of chiral oxime ethers has been achieved via two-step reaction in which the first step is the reaction of oximes 1a-f with ethyl bromoacetate in the presence of sodium hydride to give oxime ethers 2a-f which are subsequently, in the second step, reacted with different commercially available chiral amines under microwave irradiation conditions to give compounds 3a-l in good to excellent yields. Through this method, we have observed a decrease in reaction time and excellent yields than the previously described conventional method.

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30

Heravi, Majid M., Dariush Ajami, and Mohammad M. Mojtahedi. "Regeneration of Carbonyl Compounds from Oximes on Clayfen under Conventional Heating and Microwave Irradiation." Journal of Chemical Research 2000, no. 3 (March 2000): 126–27. http://dx.doi.org/10.3184/030823400103166652.

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31

Bolotin, Dmitrii S., Nadezhda A. Bokach, and Vadim Yu Kukushkin. "Coordination chemistry and metal-involving reactions of amidoximes: Relevance to the chemistry of oximes and oxime ligands." Coordination Chemistry Reviews 313 (April 2016): 62–93. http://dx.doi.org/10.1016/j.ccr.2015.10.005.

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32

Pícha, Jan, Radek Cibulka, František Hampl, František Liška, Patrik Pařík, and Oldřich Pytela. "Reactivity of p-Substituted Benzaldoximes in the Cleavage of p-Nitrophenyl Acetate: Kinetics and Mechanism." Collection of Czechoslovak Chemical Communications 69, no. 2 (2004): 397–413. http://dx.doi.org/10.1135/cccc20040397.

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Eleven p-substituted benzaldoximes (p-XC6H4CH=NOH, where X = H, CH3, CF3, F, Cl, Br, OCH3, N(CH3)2, COOCH3, CN, NO2) have been synthesized and their dissociation constants determined in 10% (v/v) aqueous dioxane at 35 °C. Under the same conditions, the pseudo-first order rate constants kobs of their reactions with p-nitrophenyl acetate (PNPA) were measured at pH values from 7.8 to 10.8 and at concentrations coxime ranging from 0 to 4.00 × 10-3 mol l-1. The kinetic model and mechanism of the said reaction was proposed by means of mathematical statistical modelling of the dependences of kobs on pH and coxime. The mechanism involves a pre-equilibrium (k-1/k1) in which PNPA forms a tetrahedral intermediate (THI) with the deprotonated form of oxime. In the given medium, THI is in equilibrium with the non-reactive conjugated acid THIH (dissociation constant Ka,THIH) which is stabilized by intramolecular hydrogen bond. Depending on pH, the rate-limiting step consists either in formation of THI from educts (pH < pKa,oxime) or in its spontaneous (k2) and oxime-catalyzed (k3, general acid catalysis) decomposition to products (pH > pKa,oxime). Evaluation of substituent effects on dissociation constants (Ka,oxime) of the oximes showed that there is no direct conjugation between the substituent and the reaction centre (the found reaction constant ρ(Ka,oxime) = 0.91). The transmission coefficient of the transfer of these effects through C=N-O grouping corresponds approximately to one bond. The reaction constants in the Hammett equation obtained from the regression model are: ρ(k-1Ka,THIH/k1) = 1.29, ρ(k2Ka,THIH) = 0.20 and ρ(k3Ka,THIH) = 0.67. These reaction constants have been discussed with the regard to the reaction mechanism suggested.

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33

Mukherjee, Soma, Abhijeet P. Bapat, Megan R. Hill, and Brent S. Sumerlin. "Oximes as reversible links in polymer chemistry: dynamic macromolecular stars." Polym. Chem. 5, no. 24 (2014): 6923–31. http://dx.doi.org/10.1039/c4py01282h.

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34

Bhattacharyya, Aditya, Subhomoy Das, Navya Chauhan, Pronay K. Biswas, and Manas K. Ghorai. "Facile Synthesis of Oxime Amino Ethers via Lewis Acid Catalyzed SN2-Type Ring Opening of Activated Aziridines with Aryl Aldehyde Oximes." Synlett 31, no. 07 (March 2, 2020): 708–12. http://dx.doi.org/10.1055/s-0039-1691596.

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A simple strategy to access a wide range of substituted oxime amino ethers in good to high yields via Lewis acid catalyzed SN2-type ring opening of activated aziridines with aryl aldehyde oximes is reported.

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35

Iesce, M. Rosaria, Flavio Cermola, and Antonio Guitto. "Carbonyl Oxide Chemistry. 6.1N-(Hydroperoxyalkyl)keto Nitrones and α-Oxime Ether Hydroperoxides via Disubstituted Carbonyl Oxides and Oximes†." Journal of Organic Chemistry 63, no. 25 (December 1998): 9528–32. http://dx.doi.org/10.1021/jo9806916.

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36

Wang, Shujiang, Ganesh N. Nawale, Oommen P. Oommen, Jöns Hilborn, and Oommen P. Varghese. "Influence of ions to modulate hydrazone and oxime reaction kinetics to obtain dynamically cross-linked hyaluronic acid hydrogels." Polymer Chemistry 10, no. 31 (2019): 4322–27. http://dx.doi.org/10.1039/c9py00862d.

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37

Möhrle, Hans, and Michael Gehlen. "Reaktionsbeteiligung Von Oximfunktionen Bei Der Dehydrierung Von 2-Phenylpiperidin-Derivaten." Zeitschrift für Naturforschung B 62, no. 6 (June 1, 2007): 841–53. http://dx.doi.org/10.1515/znb-2007-0614.

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Mercury(II)-induced dehydrogenation of α-(2-phenylpiperidin-1-yl)-acetophenone oximes 7 gives rise to two different iminium compounds which subsequently react with the neighbouring oxime group. With the mercury(II)-EDTA reagent, (E)-7 forms the cyclic nitrones 9 and 11a, b, whereas (Z)-7 is transformed into oxadiazines 12 and 13a, b. The pairs of diastereomers 11a, b and 13a, b result from the equilibrium involving an iminium oximate species. The introduction of electron donor or acceptor groups into the phenyl substituent in (E)-15 and (E)-16 does not influence significantly the direction of dehydrogenation. With mercury(II) acetate in dilute acetic acid no specifity of the oxime configuration is observed, and the nitrones and oxadiazines are produced together. This may be explained by a reaction with the acetate ion at the iminium oxime stage. NMR experiments in CDCl3 have shown that treatment of nitrone 2 and oxadiazine 3 with CF3COOD causes ring cleavage by prototropy and after longer reaction times generates the same imidazole 23

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38

Canaj, Angelos B., Lydia E. Nodaraki, Katarzyna Ślepokura, Milosz Siczek, Demetrios I. Tzimopoulos, Tadeusz Lis, and Constantinos J. Milios. "A family of polynuclear cobalt complexes upon employment of an indeno-quinoxaline based oxime ligand." RSC Adv. 4, no. 44 (2014): 23068–77. http://dx.doi.org/10.1039/c4ra01914h.

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Spahić, Zlatan, Tomica Hrenar, and Ines Primožič. "Polytopal Rearrangement Governing Stereochemistry of Bicyclic Oxime Ether Synthesis." International Journal of Molecular Sciences 23, no. 20 (October 15, 2022): 12331. http://dx.doi.org/10.3390/ijms232012331.

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In the present study, four O-substituted oximes of quinuclidin-3-one were synthesized using appropriate O-substituted hydroxylamine hydrochlorides. In order to perform these reactions in a solvent, a mixture of (E) and (Z) products was yielded. Using mechanochemical and microwave synthesis, we then obtained pure (E) oximes. In almost all cases, the conversion to oxime ethers was completed. Reactions were monitored by ATR spectroscopy and the ratios of (E) and (Z) oxime ethers were deduced from 1H NMR data. Several reactions were very rapid (1 min) with 100% conversion and stereospecificity. To investigate the reaction mechanisms, full conformational analyses of the reaction intermediates were performed and the lowest energy conformers were determined. These conformers differed in spatial arrangement around the nitrogen atom of the amino group and were in the correct orientation for reactions to occur. Calculated standard Gibbs energies of the formation were in agreement with the experimentally obtained ratios of (E) and (Z) isomers. This work shows alternatives to the classical synthesis of O-substituted oxime ether precursors and highlights the fast reaction rate and stereoselectivity of microwave synthesis as well as the “green” aspects of mechanochemistry.

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Sejbal, Jan, Jiří Klinot, and Alois Vystrčil. "Photolysis of 19β,28-epoxy-18α-oleanan-2β-ol nitrites: Functionalization of 10β- and 8β-methyl groups." Collection of Czechoslovak Chemical Communications 53, no. 1 (1988): 118–31. http://dx.doi.org/10.1135/cccc19880118.

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On photolysis, 19β,28-epoxy-18α-oleanan-2β-ol nitrite (I) undergoes functionalization of the 10β-methyl group (formation of oxime II) as well as of the rather distant 8β-methyl group (leading to oxime III). No products of attack at the 4β-methyl group have been found. The 2β-nitrolyloxy-3β-acetoxy derivative XX reacts similarly whereas its 2β-nitrosyloxy-3α-acetoxy isomer XIII is photolyzed to give diol XI. Oximes II and III were converted into two series of nitriles (a and b) with various functional groups on the ring A. Structure of all compounds was derived from their spectral data. Double radical transfer has been proposed for functionalization of the 8β-methyl group (position 26).

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41

Abele, Edgars, and Ramona Abele. "Oximes of Nucleosides and Related Compounds: Synthesis, Reactions and Biological Activity." Current Organic Synthesis 15, no. 5 (July 5, 2018): 650–65. http://dx.doi.org/10.2174/1570179415666180524112811.

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Background: Literature data on the synthesis and structure of oximes of nucleosides and related nitrogenous bases from pyrimidine and purine were reviewed. Synthesis of novel heterocyclic systems from nucleoside oximes related pyrimidine oximes was described. The biological activity of derivatives of nucleoside and nitrogenous base oximes was also reviewed. <p> Objective: The review focuses on the recent progress in the area of nucleoside oxime synthesis, reactions and biological activity. Conclusion: In summary, literature data on the synthesis and structure of oximes of nucleosides and related nitrogenous bases derived from pyrimidine, which play an important role in the biological processes, were reviewed. Synthesis of novel heterocyclic systems from nucleoside oximes related pyrimidine oximes was described. The biological activity of derivatives of nucleoside and nucleotide oximes was also reviewed. The studied class of compounds show a wide range of imino-amino and imino-nitroso tautomerism, which was investigated in the presented literature by 1H, 13C and 15N NMR spectroscopy methods. Also, according to the authors point of view, due to imino-amino and/or imino-nitroso tautomerism the nucleoside oximes show interesting activity. Most of the compounds exhibit biological activity characteristic of not only oxime derivatives, but also activity of hydroxylamines or nitroso compounds.

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42

Jagtap, S. B., N. N. Patil, B. P. Kapadnis, and B. A. Kulkarni. "Characterization and Antimicrobial Activity of Erbium(III) Complexes of C-3 Substituted 2-hydroxy-1,4-naphthalenedione-1-oxime Derivatives." Metal-Based Drugs 8, no. 3 (January 1, 2001): 159–64. http://dx.doi.org/10.1155/mbd.2001.159.

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Erbium(III) complexes of 2-hydroxy-l,4-naphthalenedione-1-oxime and its C-3 substituted derivatives are synthesized and characterized by elemental analysis, thermogravimetric analysis, infrared spectroscopy, magnetic susceptibility measurements 2-hydroxy-1,4-naphthalenedione-1-oxime derivatives are analysed using H1 and C13 NMR spectroscopy. The molecular composition of the synthesized complexes is found to be [ML3(H2O)2]. The antimicrobial activity of these complexes is determined by well diffusion method against the target microorganisms- Staphylococcus aureus, Xanthomonas campestris, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. The antimicrobial activities of 2- hydroxy-1,4-naphthalenedione-1-oximes and their complexes are compared. It is observed that 2-hydroxy-1,4-naphthalenedione-l-oximes exhibit higher antifungal activity as compared to antibacterial activity. These activities are reduced upon complexation of these oximes with Erbium.

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Sasaki, Kenji, Ying-Xue Zhang, Hiroshi Yamamoto, Setsuo Kashino, and Takashi Hirota. "Polycyclic N-Heterocyclic Compounds. Part 54. Ring-cleavages and Ring-closures of N-(Benzo[h]quinazolin-4-yl)amidine and its Amide Oxime Derivatives with Hydroxylamine." Journal of Chemical Research 23, no. 2 (February 1999): 92–93. http://dx.doi.org/10.1177/174751989902300213.

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The synthesis of abnormal cyclization products, 2-(3-alkyl(or aryl)[1,2,4]oxadiazol-5-yl)-3,4-dihydro-1-naphthylaminoformaldehyde oximes and their homologues, by the reaction of N-(benzo[ h]quinazolin-4-yl)amidine or its amide oxime derivatives with excess NH2OH · HCI are described.

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Higgins, Sean, David G. Morris, Kenneth W. Muir, and Karl S. Ryder. "The chiral oxime of 13H-dibenzo(a,i)fluoren-13-one." Canadian Journal of Chemistry 82, no. 11 (November 1, 2004): 1625–28. http://dx.doi.org/10.1139/v04-133.

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On the basis of single crystal diffraction analyses it is shown that conversion of 13H-dibenzo(a,i)fluoren-13-one into its oxime causes distortion of the aromatic framework because of steric crowding. The oxime is, in consequence, chiral.Key words: oxime, crystal structure, chirality.

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Linder, K. E., S. Unger, and A. D. Nunn. "CHEMISTRY AND BIODISTRIBUTION OF TIN-CAPPED Tc-OXIMES [(Tc(OXIME)3 (μ-OH)SnCl3]." Clinical Nuclear Medicine 13, no. 5 (May 1988): 395. http://dx.doi.org/10.1097/00003072-198805000-00051.

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46

Parker, B. F., S. Hohloch, J. R. Pankhurst, Z. Zhang, J. B. Love, J. Arnold, and L. Rao. "Interactions of vanadium(iv) with amidoxime ligands: redox reactivity." Dalton Transactions 47, no. 16 (2018): 5695–702. http://dx.doi.org/10.1039/c7dt04069e.

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Vanadium is the main competitor for uranium extraction from seawater, and V(iv) comprises a minor but important portion of this. V(iv) undergoes redox reactions with oximes and amidoxime ligands under seawater-relevant conditions, leading to V(v) complexes and loss of oxime functional groups.

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Anandhan, Ramasamy, Mandapati Bhargava Reddy, and Murugesan Sasikumar. "Development of novel triazole based dendrimer supported spiroborate chiral catalysts for the reduction of (E)-O-benzyl oxime: an enantioselective synthesis of (S)-dapoxetine." New Journal of Chemistry 43, no. 38 (2019): 15052–56. http://dx.doi.org/10.1039/c9nj03217g.

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A reusable dendrimer supported spiroborate catalysts 2 and 3 have been synthesized via a “click” chemistry and demonstrated as catalysts for the reduction of (E)-O-benzyl oxime 13 to synthesis of (S)-dapoxetine 14 with 94% ee and 46% overall yield.

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Singh, Surinderjit, M. PS Ishar, Gajendra Singh, and Rajinder Singh. "Efficient, microwave-assisted intramolecular 1,3-dipolar cycloadditions of oximes and N-methylnitrones derived from o-alkenylmethoxy-acetophenones." Canadian Journal of Chemistry 83, no. 3 (March 1, 2005): 260–65. http://dx.doi.org/10.1139/v05-049.

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Contrary to literature reports, the o-allyloxy- and crotyloxy-acetophenone-oximes (2a, 2b) are transformed to nitrones, which undergo regio- and stereoselective intramolecular 1,3-dipolar cycloadditions, both on microwave heating under solvent free conditions and refluxing in toluene, to afford novel cycloadducts (5a, 5b); the oxazepine-N-oxide (3a) reported to be formed in 98% yield was obtained only as a minor product (~10%). However, o-cinnamyloxy-acetophenone-oxime (2c) under similar conditions undergoes intramolecular N-alkylation to afford nitrone (3c). The reactions carried out under microwave irradiation are cleaner, require shorter reaction times, and have higher yields. Corresponding intramolecular 1,3-dipolar cycloadditions of N-methylnitrones (B), generated in situ from o-alkenylmethoxy-acetophenones (1a1c) and N-methylhydroxylamine under solvent-free microwave irradiation conditions, are completely regio- and stereoselective, require much shorter reaction times, and afford adducts (4a4c) in higher yields, as compared with their thermal counterparts.Key words: cycloadditions, nitrones, oximes, o-alkenylmethoxy-acetophenones, microwave, isoxazolidines.

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Baláž, Matej, Zuzana Kudličková, Mária Vilková, Ján Imrich, Ľudmila Balážová, and Nina Daneu. "Mechanochemical Synthesis and Isomerization of N-Substituted Indole-3-carboxaldehyde Oximes †." Molecules 24, no. 18 (September 14, 2019): 3347. http://dx.doi.org/10.3390/molecules24183347.

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Performing solution-phase oximation reactions with hydroxylamine hydrochloride (NH2OH·HCl) carries significant risk, especially in aqueous solutions. In the present study, four N-substituted indole-3-carboxaldehyde oximes were prepared from the corresponding aldehydes by solvent-free reaction with NH2OH·HCl and a base (NaOH or Na2CO3) using a mechanochemical approach, thus minimizing the possible risk. In all cases, the conversion to oximes was almost complete. The focus of this work is on 1-methoxyindole-3-carboxaldehyde oxime, a key intermediate in the production of indole phytoalexins with useful antimicrobial properties. Under optimized conditions, it was possible to reach almost 95% yield after 20 min of milling. Moreover, for the products containing electron-donating substituents (-CH3, -OCH3), the isomerization from the oxime anti to syn isomer under acidic conditions was discovered. For the 1-methoxy analog, the acidic isomerization of pure isomers in solution resulted in the formation of anti isomer, whereas the prevalence of syn isomer was observed in solid state. From NMR data the syn and anti structures of produced oximes were elucidated. This work shows an interesting and possibly scalable alternative to classical synthesis and underlines environmentally friendly and sustainable character of mechanochemistry.

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Hudák, Alexander, Adam Košturiak, Alexander Hanudeľ, and Pavol Meľuch. "Cathodic Reduction of Isatin-3-oxime." Collection of Czechoslovak Chemical Communications 58, no. 8 (1993): 1803–12. http://dx.doi.org/10.1135/cccc19931803.

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The molecule of isatin-3-oxime was studied polarografically over the region of pH 1 to 13. Cathodic reduction within the region of pH 1 to 10.5 gives rise to a single four-electron polarographic wave due to the reduction of the oxime group, whereas two polarographic waves are observed at pH 10.5 to 13: one is due to the reduction of the isatin-3-oxime anion, the other, more negative wave is associated with the reduction of the oxime group in the α-oxime isatinic acid anion, which is the product of hydrolytic cleavage of the isatin ring in the basic pH region. The experimental results give evidence that the substance can exist as seven ionic and molecular species in dependence on pH. The species have been confirmed polarographically, by IR and electronic spectroscopy, potentiometrically and by paper electrophoresis.

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Journal articles on the topic 'Oxime Chemistry'

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