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Hydroxylamines 0-alkyl

Thus the structure of the oxazirane must formally involve elimination of water from one molecule each of the carbonyl compound and of an alkyl hydroxylamine. (In the synthesis of oxazirane from N-methylhydroxylamine-O-sulfonic acid and benzaldehyde, this method... [Pg.90]

Here a typical property of three-membered rings wdth two hetero atoms is shown and this property is also found in the diaziridines. Only with the oxaziranes which are substituted by aryl groups in the 3-position does the hydrolysis by acids occur according to Eq. (14) with formation of an aromatic aldehyde and alkyl hydroxylamine. [Pg.93]

The acid-catalyzed hydrolysis of 3-aryloxaziranes is a useful process for the syntheses of alkyl hydroxylamines. Emmons prepared, e.g., tert-butylhydroxylamine in 82% yield and ferOoctyl-hydroxylamine in 86% yield Horner and Jurgens - obtained c clo-hexylhydroxylaminc in 70% yield. [Pg.93]

The reaction is thought to occur by nucleophilic addition of the N-alkyl-hydroxylamine to the keto acid as if forming an oxime (Section 19.8), followed by decarboxylation and elimination of wrater. Show the mechanism. [Pg.1056]

Die Reduktion von Hydroxylaminen mit Hydriden lauft analog der Reaktion von Nitro-so-Verbindungen bzw. Oximen. N-Alkyl-hydroxylamine werden durch Lithiumanalanat in der Regel zu prim. Aminen umgesetzt8, doch konnen auch Umlagerungen zum sek. Amin ablaufen9. [Pg.480]

In the mechanism study of /V-benzyl-/V -alkyl hydroxylamines, regarding oxidation with HgO and p-benzoquinone, it has been proposed on the basis of intra- and intermolecular kinetic isotope effects that, initially, there takes place a one-electron transfer from a nitrogen atom to the oxidant, with a subsequent proton abstraction (106—108). [Pg.143]

Table 2.5 Formation of optically active functionalized fS-hydroxy-nitroncs 95 by reaction of aldehydes 93 with activated carbonyl compounds 94 and substituted N -alkyl hydroxylamine hydrochloride in the presence of L-proline as the catalyst... Table 2.5 Formation of optically active functionalized fS-hydroxy-nitroncs 95 by reaction of aldehydes 93 with activated carbonyl compounds 94 and substituted N -alkyl hydroxylamine hydrochloride in the presence of L-proline as the catalyst...
Alkylation of nitrones and formation of a-alkylated hydroxylamines proceeds upon treatment with trialkylboranes (578). [Pg.250]

Photoexcited nitrobenzene may be used for benzylic hydroxylation (at C-9) of 17/3-acetoxy-3-methoxyoestra-l,3,5(10)-triene. The photochemistry of the 17/3-nitro-steroid (217) is markedly solvent dependent, the major products being in ether the 17-desnitro-compound (218), in propan-2-ol the hydroxylamine (219), and in EtOH-NaOEt the hydroxamic acid (220) and the cyclopropane (221). The hydroxamic acid (220) is probably formed through the oxaziridine (Scheme 7). Although there are analogies to this in the photochemistry of nitrones and oximes, the photoreduction of a nitroalkane in propan-2-ol to an alkyl-hydroxylamine appears to have no precedent. Further studies of photochemistry of conjugated... [Pg.257]

The field of reductive preparations for the formation of nitroso compounds has not yet been adequately explored. For example, only indirect evidence exists that the electrolytic reduction of f-nitroalkanes to tertiary alkyl-hydroxylamines proceeds by way of nitroso compounds. [Pg.201]

It is natural to presuppose that the reduction of nitro compounds should lead to the nitroso compounds, at least as an intermediate stage. Until quite recently, no reductive processes for the formation of nitrosoalkanes were known [3], More recently, some indirect evidence is said to show that, on electrolytic reduction of tertiary aliphatic nitro compounds, the final t-alkyl-hydroxylamines are produced by the intermediate formation of nitroso compounds which were not isolated [99]. [Pg.217]

Dihydroisoxazoles with a substituent at nitrogen are most conveniently prepared by 1,3-dipolar cycloaddition of nitrones to alkenes or alkynes. Nitrones are usually prepared in situ from carbonyl compounds and /V-(alkyl)hydroxylamines (Figure 15.10). [Pg.418]

Primary amines are oxidized to the corresponding oximes. The sequence of reactions closely parallels the sequence observed with other mono oxygen donors, i.e., oxidation to alkyl hydroxylamines (V) followed by oxidation to alkylnitroso compounds (VI) which, via a prototropic shift, rearrange to the oximes (VII) ... [Pg.315]

N-Nitroso-N-alkylhydroxyl-amine, N-Alkyl-hydroxylamine Anwesenheit von H-Donator NO y-NH-OH 106, 119) H... [Pg.136]

The reduction of nitroparaffins to amines has been realized with a great variety of reducing agents. Under reducing conditions somewhat milder than those required to produce the amines, the intermediate alkyl hydroxylamines and oximes are produced.20... [Pg.296]

The reduction of aliphatic nitro-hydrocarbons in dilute alcoholic sulphuric-acid solution has been accomplished by Pierron.2 The /5-alkyl-hydroxylamines are obtained at platinum anodes and at a temperature of 15°-20° ... [Pg.56]

Selective reductions. Borch et af. have recenlly reported a study of the reduction of various organic functional groups with sodium cyanoborohydride. Under neutral conditions, carbonyl groups are reduced to a negligible extent, but reduction is rapid at pH 3 4. Ketoximes are reduced smoothly at pH 4 to the corresponding alkyl-hydroxylamines. Reduction of aldoximes results mainly in the dialkylhydroxylaminc. [Pg.450]

A similar rate expression has also been established for N-methyl hydroxylamines, and is known in the nitrosation of aromatic amines. With O-alkyl hydroxylamines the expression has the more usual form... [Pg.299]

The following reaction mechanism was ruled out by the authors cited [4 + 2] cycloaddition of the diene with the nitrone to give tertiary amine oxide, 7-21, which then thermally rearranges to the product. (Thermal rearrangement of a tertiary amine oxide to an alkylated hydroxylamine is called a Meisenheimer rearrangement.)... [Pg.425]

Oximes.—Oximes of some saturated ketones are reduced by aqueous alkaline sodium borohydride under reflux to give the corresponding alcohols. Selective reduction of a 3,17-dioxime is possible, at C(3). a -Oximino-ketones afford diols. Diborane, in contrast, reduces oximes to give alkyl hydroxylamines a recent variant using sodium borohydride on silica gel in benzene gave the... [Pg.280]

Both O-alkyl hydroxylamines and, especially, arylhydrazines, are slightly oxidized compounds. The presence of any oxidizers in the reaction mixtures must be excluded. Nevertheless, in real practice, these mixtures very often contain some by-products (e.g., ArNH2, ArOH, ArH, etc.). Usually, there are no problems to reveal their chromatographic peaks, because aU of them have lower retention parameters than those for the initial reagents and, moreover, all target derivatives. The condensation reaction of the considered type can be characterized by statistically processed differences of retention indices of products and initial substrates. This mode of additive scheme permits us to estimate these analytical parameters for any new derivatives on standard nonpolar polydimethyl siloxanes. For the simplest reaction scheme, Ah— —>Bh—, AMW = MW(B) -MW(A) and ARl, = RI(B) RI(A) ... [Pg.502]

AU considered condensation reactions have some anomalies for the a,j8-unsaturated carbonyl compounds. Most reagents with active hydrogen atoms can react not only with carbonyl groups but also with polarized conjugated double bonds C = C. As a result of this regularity, three products, instead of the estimated one target derivative, are formed in the reactions of a,)8-unsaturated carbonyl compounds with O-alkyl hydroxylamines ... [Pg.502]

A number of syntheses of (V-hydroxy-a-amino acids and derivatives thereof have been reported. a-Bromocarboxylic acids or their r-butyl esters can be treated with hydroxylamine or 0-alkylated hydroxylamines to give the corresponding hydroxylamine derivatives. yV-Benzyloxy-t-alanine has been obtained by reaction of (/ )-a-bromopropionic acid with O-benzylhydroxylamine. But due to bromide exchange the optical yield was low. Anchimeric assistance of a suitable attached thio group can bring... [Pg.113]

Aldoxime lassen sich nicht zu N-Alkyl-hydroxylaminen zu hydrieren, vielmehr erhalt man z. B. mit Platin in alkoholischer Salzsaure unter Verbrauch von 1,5 Mol Wasserstoff 1,1-Dialkyl-hydroxylamine1. Diese entstehen wahrscheinlich durch Hydrierung in-termediar auftretender Nitrone (s. S. 253 f.), die sich leicht aus N-Alkyl-hydroxylamin und durch Hydrolyse entstandenem Aldehyd bilden ... [Pg.251]


See other pages where Hydroxylamines 0-alkyl is mentioned: [Pg.69]    [Pg.175]    [Pg.21]    [Pg.375]    [Pg.160]    [Pg.175]    [Pg.666]    [Pg.62]    [Pg.356]    [Pg.69]    [Pg.217]    [Pg.36]    [Pg.75]    [Pg.34]    [Pg.191]    [Pg.567]    [Pg.69]    [Pg.496]    [Pg.191]    [Pg.250]   
See also in sourсe #XX -- [ Pg.56 ]




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Hydroxylamines O-alkyl

Hydroxylamines alkylation

Hydroxylamines alkylation

N-Alkylation hydroxylamines

O-Alkylation hydroxylamines

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