N-alkyl Nitrones Research Articles

N-Alkyl nitrones as substrates for access to N-aryl isoxazolidines via a catalyst-free one-pot three-component reaction with nitroso compounds and olefins

N-Alkyl nitrones are used as starting materials to construct N-aryl isoxazolidines, instead of N-alkyl isoxazolidines or N–H 1,3-oxazinanes via a catalyst-free one-pot three-component reaction with nitrosoarenes and olefins.

Efficient method for the synthesis of 1,2,3-triazole functionalized isoxazolidine derivatives by 1,3-dipolar cycloaddition of nitrones with terminal olefins

ABSTRACT1-Phenyl-1,2,3-triazole-4-carbaldehyde 1 was treated with different N-alkyl hydroxylamine hydrochlorides 2 using NaHCO3 to obtain 1,2,3-triazole substituted N-alkyl nitrones 3a–c. The nitrones 3a–c were further reacted with different substituted olefins and furnished 2-alkyl-3-(1-phenyl-1H-1,2,3-triazol-4-yl)-5-(substituted)isoxazolidine derivatives 4a–p in high yields via 1,3-dipolar cycloaddition reaction.

Synthesis, structure, theoretical and experimental in vitro antioxidant/pharmacological properties of α-aryl, N-alkyl nitrones, as potential agents for the treatment of cerebral ischemia

The synthesis, structure, theoretical and experimental in vitro antioxidant properties using the DPPH, ORAC, and benzoic acid, as well as preliminary in vitro pharmacological activities of (Z)-α-aryl and heteroaryl N-alkyl-nitrones 6-15, 18, 19, 21, and 23, is reported. In the in vitro antioxidant activity, for the DPPH radical test, only nitrones bearing free phenol groups gave the best RSA (%) values, nitrones 13 and 14 showing the highest values in this assay. In the ORAC analysis, the most potent radical scavenger was nitrone indole 21, followed by the N-benzyl benzene-type nitrones 10 and 15. Interestingly enough, the archetypal nitrone 7 (PBN) gave a low RSA value (1.4%) in the DPPH test, or was inactive in the ORAC assay. Concerning the ability to scavenge the hydroxyl radical, all the nitrones studied proved active in this experiment, showing high values in the 94-97% range, the most potent being nitrone 14. The theoretical calculations for the prediction of the antioxidant power, and the potential of ionization confirm that nitrones 9 and 10 are among the best compounds in electron transfer processes, a result that is also in good agreement with the experimental values in the DPPH assay. The calculated energy values for the reaction of ROS (hydroxyl, peroxyl) with the nitrones predict that the most favourable adduct-spin will take place between nitrones 9, 10, and 21, a fact that would be in agreement with their experimentally observed scavenger ability. The in vitro pharmacological analysis showed that the neuroprotective profile of the target molecules was in general low, with values ranging from 0% to 18.7%, in human neuroblastoma cells stressed with a mixture of rotenone/oligomycin-A, being nitrones 18, and 6-8 the most potent, as they show values in the range 24-18.4%.

1H– 15N HMBC as a valuable tool for the identification and characterization of nitrones

1H– 15N HMBC has been evaluated as an efficient and high-speed method to determine 15N chemical shifts for nitrones, which can be used to identify aromatic nitrones and to extract structural information by comparison with reference data. Substituent effects have been measured on C and N aryl groups separately, showing up the influence of electronic effects on C-aryl groups rather than N-aryl groups on the 15N chemical shifts. Steric effects are remarkable in the case of C-aryl- N-alkyl nitrones. Depending on N or C substitution, chemical shift changes in such an additive way that it is possible to predict chemical shifts for unknown nitrones.

Palladium(II)-catalyzed 1,3-dipolar cycloaddition of nitrones with enol ethers

The 1,3-dipolar cycloadditions of enol ethers as electron-rich olefins with C-phenyl- N-alkyl nitrones proceeded smoothly in the presence of easy handling palladium(II) catalysts under mild conditions to give isoxazolidines in good yield.

Chromium and Tungsten Pentacarbonyl Groups as Reactivity and Selectivity Auxiliaries in [3 + 2] Cycloaddition of Alkynyl Fischer Carbene Complexes with N-Alkyl Nitrones

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChromium and Tungsten Pentacarbonyl Groups as Reactivity and Selectivity Auxiliaries in [3 + 2] Cycloaddition of Alkynyl Fischer Carbene Complexes with N-Alkyl NitronesKin Shing Chan, Ming Lok Yeung, Wai-kin Chan, Ru-Ji Wang, and Thomas C. W. MakCite this: J. Org. Chem. 1995, 60, 6, 1741–1747Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://doi.org/10.1021/jo00111a036RIGHTS & PERMISSIONSArticle Views944Altmetric-Citations65LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (903 KB) Get e-Alerts Get e-Alerts

Direct synthesis of isoxazolidinylphosphines by cycloaddition of nitrones to diphenylphosphinoethenes and x-ray structure of 7,7-dimethyl-1-oxo-1-phenyl-3-diphenylphosphinyl-hexahydro-1H-pyrrolo [1,2-c] [1,3,2] oxazaphosphorine

The 1,3-dipolar cycloaddition reaction of N-alkyl nitrones with diphenylvinylphosphines affords directly isoxazolidinylphosphines in satisfactory yields and in regio- and stereoselective manner. The parent diphenylvinylphosphine was found to favor the formation of 5-phosphinoisoxazolidines whereas diphenylpropenylphosphine gave instead the 4-phosphinoisoxazolidine regioisomer. However, in reactions utilizing on alkylarylvinylphosphine and/or N-arylnitrone, oxidation of the phosphine by the nitrone reagent was found to precede the cycloaddition. An attempted conversion of the bicyclic isoxazolidine derived from 2,2-dimethyl-dihydro-2H-pyrrole 1-oxide and diphenylvinylphosphine to the perhydropyrrolo[1,2-c] [1,3,2]oxaza-phosphorine ring system was accomplished through the use of the corresponding phosphine oxide derivative and provided a single diastereoisomer of the desired pyrrolooxazaphosphorinane characterized ultimately in the form of its dioxide hydrate by the X-ray diffraction technique.

Charge-transfer complexes of nitrones—IV. Molecular complexes of N-alkyl nitrones with π-acceptors

Charge-transfer complexes between C-phenyl-N-alkyl nitrones and tetracyanoethylene, 2,3-dichloro-5,6-dicyanobenzoquinone, 7,7,8,8-tetracyanoquinodimethane, tetrafluorocyclohexa-2,5-diene-1,4-dione and tetrachlorocyclohexa-2,5-diene-1,4-dione were studied spectrophotometrically in methylene chloride at 25°C. The spectroscopic data indicate that the complexes are weak in nature and the PhCH▪N → 0 group is responsible for the complexation with π-acceptors. Job's method shows that the stoichiometric ratio of the complexes is 1 : 1. The effect of temperature and solvents on the stability of the charge-transfer complexes is discussed.

Ketene. Part 21. Reactions of heterocumulenes with nitrones

Degradative and mass spectrometric evidence confirms the formation of the isoxazolidinones (2) from the reaction of cyano-t-butylketene with the N-alkyl nitrones (1), whilst the reaction with the N-phenyl nitrone (1d) gives the expected oxazolidinone (3b). Cyano-t-butylketene reacts with diphenyl nitrone to give the indolones (10a) and (10b). The reaction of phenyl isocyanate with diphenyl nitrone, and the N-alkyl nitrones (1a) and (1d) gives the normal 1,3-dipolar cycloadducts without rearrangement.Ethoxycarbonyl-t-butylketene reacts with the N-phenyl nitrone (1d) to give an oxazolidinone, but reaction with the N-alkyl nitrones (1) gives only fiuorenone azine. This ketene reacts with diphenyl nitrone to give the anil (15) and the dihydroindole (16).