Hydroxylamines bromine oxidation

Fluoro-2,2-dinitroethylamine is oxidized by m-chloroperoxybenzoic acid 10 the corresponding hydroxylamine, which, on further oxidation by a second equivalent of the peroxyadd or bromine, gives an oxime [85] (equation 77)... 

A somewhat unusual sequence to generate azepanones 80 involved the intramolecular addition of hydroxylamines to alkynes 76 to form cyclic nitrones 77. A vinyl magnesium bromide addition at low temperatures and a reduction with TiCls followed by N-Boc protection led to the azepane 78. Double bond bromination and subsequent RUO4 oxidation gave the lactam 79. Several further steps allowed the generation of the lactam structure 80 proposed for d,/-aca-cialactam, but the spectral data of the synthetic material differed from that of the natural product (Scheme 16)] [23 a, b]. 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

Following a similar approach, the first bis(triorganosilyl) diazene 402 that is stable at room temperature could be obtained.410 Thus, the reaction of (/-Bu2MeSi)HNNH(SiMe/-Bu2) 403, an analog of 399, with 2 equiv. of BuLi has provided (/-Bu2MeSi)LiNNLi(SiMe/-Bu2) 404, whose oxidation with bromine has led to the formation of the diazene /-Bu2MeSiNNSiMe/-Bu2 402 (Scheme 58). Recently, the stepwise synthesis of cyclic and open-chain silyl hydro-xylamines has been reported by Klingebiel < / /.411 14 For hypervalent silyl hydroxylamines, see Section 6.8. 

Intramolecular addition of hydroxylamines and hydroxamic acids to the non-activated double bonds is possible through oxidative cyclization. Reaction of O-Acyl fi,y-unsaturated hydroxamates (e.g. 56, equation 38) with bromine provides 3,4-substituted iV-hydroxy -lactams such as 57 with high diastereoselectivity. Analogous reaction of O-benzyl hydroxylamine 58 (equation 39) with iodine results in five-membered cyclization with 2 1 ratio of diastereomers. ... 

Elemental composition H 9.15%, N 42.41%, O 48.44%. Hydroxylamine may be measured by coulometric titration to a potentiometric end point using a coulometric titration cell. A standard solution of bromine may be used as oxidizer in the redox reaction. (Skoog, D. A., D. M. West, and F. J. HoUer. 1992. Fundamentals of Analytical Chemistry, 6th ed. pp. 467, Orlando Saunders College Publishing)... 

Elemental composition H 4.92%, N 17.06%, O 58.49%, S 19.59%. The concentration of hydroxylamine sulfate in aqueous solution may be measured by coulometric titration against a standard solution of oxidizing agent, such as bromine (See Hydroxylamine). Sulfate anion may be measured by ion chromatography. 

Fluoro-2.2-dinitroethyl)aniine is not affected by hydrogen peroxide in aqueous or methanolic solution, even in the presence of transition metal catalysts.218 On the other hand, it is oxidized by 3-chloroperoxybenzoic acid to the corresponding hydroxylamine 8, which on further oxidation by a second equivalent of the peroxy acid or bromine gives an oxime (vide infra).118... 

A -(2-Fluoro-2,2-dinitroethyl)hydroxylamine (1) is oxidized by 3-chloroperoxybenzoic acid or bromine to afford oxime 2.218 This compound is unstable and over the course of several weeks at ambient temperature it rearranges quantitatively to amide 3.218 Further oxidation of the oxime 2 with nitric acid or aqueous chromic acid gives a product mixture, from which bis(fluorodinitromethyl)furoxane 4 is isolated.218... 

Enmein was converted to 20-hydroxykaur-6-en-15a-pyranylether (382), which was oxidized with chromium trioxide in pyridine to afford the aldehyde 383. The latter was converted with hydroxylamine to the oxime 384. The nitrone 385 was prepared by treatment of 384 with bromine azide. Photolysis of 385 gave the desired compound 381 in 46% yield. This intermediate possesses several useful functionalities (e.g., carbinolamine ether linkage), which may be of interest for synthesis of C20-diterpenoid alkaloids after minor changes in this scheme. 

Oxidation of 2,3-dimethylbutane-2,3-bis-hydroxylamines with bromine or sodium periodate in aqueous solution at room temperature yielded 3,3,4,4-tetramethyl-A1-l,2-diazetine-l,2-dioxide <1972JA5077, 1975JOC1409> which can be reduced to diazetidine. 

Yelinova et al. reported the oxidation of iV-[2-hydroximino-2-methyl-l-(2-pyridyl)propyl-2]hydroxylamine 239 using sodium hypobromide, generated from bromine and sodium hydroxide in cold condition (0°C), to furnish 3-bromo-3,4-dihydro-4,4-dimethyl-3-(2-pyridyl)-l,2-diazet-l,2-dioxide 240 in 26% yield (Equation 30) <2003MI395>. These oxides were evaluated for their NO donor activities in biological systems. During the last decade, not many new syntheses of diazetidines have been reported. 

Aliphatic nitroso compounds can be prepared from IV-alkylhydioxylamines oxidation widi bromine, chlorine or sodium hypochlorite in weakly acidic solution, reaction with potassium dichromate in acetic or sulfuric acid, and by oxidation widi yellow mercury(II) oxide in suspension in an organic solvent. Silver carbonate on Celite has also been used to prepare aliphatic nitroso compounds, such as ni-trosocyclohexane, in high yield from the corresponding hydroxylamines." Aqueous sodium periodate and tetraalkylanunonium periodates, which are soluble in organic solvents, are the reagents most commonly used for the oxidation of hydroxamic acids and IV-acylhydroxylamines to acylnitroso compounds... 

Sodium hypobromite, NaOBr, is prepared in situ from bromine and aqueous sodium hydroxide under cooling. Its almost exclusive application is the degradation of methyl ketones to acids with one less carbon [635, 735, 736, 737]. Such degradation is achieved not only with methyl ketones but also with other alkyl ketones [103, 160], Other oxidations, such as the conversion of hydroxylamines into nitroso compounds, are rare [738]. 

Thallium forms the monovalent thallium(I) and trivalent thallium(III) ions, the former being of greater analytical importance. Thallium(III) ions are less frequently encountered in solutions, as they tend to hydrolyse in aqueous media, forming thallium(III) hydroxide precipitate. Thallium(I) ions can be oxidized to thallium(III) ions in acid media with permanganate and hexacyanoferrate(III) ions as well as with lead dioxide, chlorine gas, bromine water or aqua regia (but not with concentrated nitric acid). The reduction of thallium(III) ions to thallium(I) is easily effected by tin(II) chloride, sulphurous acid, iron(II) ions, hydroxylamine or ascorbic acid. 

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