Studien Zum Ablauf Der Substitution XII. Umlagerung Und Thermischer Zerfall Acylierter Hydroxylamine

Horner, L.; Steppan, Hartmut

doi:10.1002/jlac.19576060103

Cited by 41 publications

(10 citation statements)

References 42 publications

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“…In previous reports, rearrangement of N ‐aryl‐ N ‐acyl‐ O ‐acylhydroxylamines (e.g. 1 ) was performed at temperatures in the range 150–200 °C 7. Rationalising that decreasing the electron‐withdrawing ability of the nitrogen protecting group would facilitate rearrangement we examined the reaction of 8 – 12 at lower temperatures than those reported, the results of which are collected in Table 1.…”

Section: Resultsmentioning

confidence: 99%

“…In 1957 Horner described the synthesis and thermal rearrangement of N ‐aryl‐ N , O ‐diacylhydroxylamine 1 to provide protected 2‐aminophenol 4 (Scheme ) 7. Subsequent mechanistic studies have shown these reactions proceed via either a [3,3]‐sigmatropic rearrangement process or an ion‐pair mechanism depending upon the reaction conditions adopted 8.…”

Section: Introductionmentioning

confidence: 99%

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Rearrangement of Differentially Protected N‐Arylhydroxylamines

2008

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The rearrangement of a series of N,O‐difunctionalised N‐arylhydroxylamines to generate protected 2‐aminophenols has been investigated. N‐Boc‐N‐Aryl‐O‐acylhydroxylamines are stable, isolable compounds which rearrange smoothly at temperatures between 110 and 140 °C. The corresponding N‐Boc‐N‐aryl‐O‐sulfonylhydroxylamines were not isolated and rearrange to 1,2‐difunctionalised aminophenols at room temperature in excellent yield. Deprotection of either the N‐ or O‐substituents under standard conditions allows for further synthetic manipulation of either the aniline or phenol functionality.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rearrangement of Differentially Protected N‐Arylhydroxylamines

2008

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“…(1a), [20] N-hydroxy-N-(4-nitrophenyl)-acetamide (1b), [21] N-(4-cyanophenyl)-N-hydroxyacetamide (1c), [22] N-(4-acetylphenyl)-N-hydroxyacetamide (1d), [23] N-hydroxy-N-(4-hydroxyphenyl)acetamide (1e), [23,24] N-hydroxy-N-phenyl-4-methoxybenzamide (2b), [25,26] N-hydroxy-N-phenyl-4-nitrobenzamide (2c), [25,27] N-hydroxy-N-phenyl-1-naphthamide (3), [28,29] and N,NЈ-dihydroxy-N,NЈ-diphenylterephthalamide (5), [30] were prepared by acylation of the corresponding N-arylhydroxylamines with the corresponding acid chlorides according to the procedure described for AHA 1a in ref. [20] All crystalline compounds were identified by 1 H NMR, 13 C NMR, and by the melting points given in the literature.…”

Section: N-hydroxyacetanilidementioning

confidence: 99%

N-Arylhydroxamic Acids as Novel Oxidoreductase Substrates

Kulys¹,

Deussen²,

Krikstopaitis³

et al. 2001

Eur. J. Org. Chem.

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Keywords: Oxidoreductases / Redox chemistry / Electrochemistry / Ab initio calculations / StructureϪactivity relationships N-Arylhydroxamic acids (AHAs) are promising novel N−OH mediators for oxidoreductase catalysis. They are electrochemically active compounds with a redox potential of 0.31−0.41 V vs. SCE. Representative oxidoreductases, e.g. fungal peroxidase from Coprinus cinereus (rCiP), catalyze the oxidation of AHAs with apparent bimolecular constants (k ox ) of 7.1·10 3 to 1.5·10 7 m −1 s −1 at pH = 8.5 and 25°C. The limiting step in substrate oxidation was the reduction of compound II (Cpd II). The oxidation constants of N-hydroxyacetanilide (1a) and N-hydroxy-N-phenylbenzamide (2a), determined by a stopped-flow and steady-state method, were similar. The decrease in the reduction rate of Cpd II reduction rate decrease occurred at pK a = 8.5 for 1a and 7.7 for 2a. The nitroxyl radical of 1a, an intermediate in the oxidation, shows decreasing stability at alkaline pH. The structure−activity relationships (SARs) of these AHAs were analyzed within the

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“…Bei der Reaktion von N-Benzoylphenylhydroxylamin (88) mit p-Toluolsulfochlorid (TsCl) in Methanol bildete sich neben dem Sulfonsaureester 90 zur Hauptsache N-Benzoyl-panisidin (91) und nur wenig N-Benzoyl-o-anisidin (92) (Schema 16) [40] (vgl. auch [41] [42]). Zwischenprodukt dieser Reaktionen ist das Hydroxylamin-0-tosylat 89.…”

Section: Ch3+unclassified

Zur Photochemie von 1H‐ und 2H‐Indazolen in saurer Lösung

Georgarakis

Schmid

Hansen

1979

Helvetica Chimica Acta

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It is shown that I Hand 2H-indazoles (cf: Scheme2) on protonation ( 0 , l~ H2S04 in water or alcoholic solution) give analogous indazolium ions (see Fig. 1 and 2) which on irradiation undergo heterolytic cleavage of the N(l), N(2) bond whereby aromatic nitrenium ions in the singlet ground state are formed (cf: Scheme 13). If the para position of these nitrenium ions is not occupied by a substituent (e.g. a methyl group) they are readily trapped by nucleophiles present (e.g. water, alcohols, chloride ions) to yield the corresponding 5-substituted 2-amino-benzaldehydes or acetophenones (cf: Schemes 4-10). Photolysis of indazole (4) and 3-methyl-indazole (5) in 0,75 N H$O, in alcoholic solutions gives in addition minor amounts of the corresponding 3-substituted 2-amino-benzaldehydes and acetophenones, respectively (cf: Schemes 6 and 8 and Table 2). Phenylnitrenium ions carrying a methyl group in the para position give in aqueous sulfuric acid mainly the reduction products, i.e. 2-amino-5-methyl-benzaldehydes (cf: Schemes I 1 and 12 and Table 3). In methanolic sulfuric acid, in addition to the reduction products, 6-methoxy substituted benzaldehydes are found (cf: Schemes I 1 and 12 and Table 3) which are presumably formed by an addition-elimination mechanism (cf: Scheme 18). It is assumed that precursors of the reduction products are the corresponding nitrenium ions in the triplet ground state. Singlet-triplet conversion of the nitrenium ions may become efficient when addition of nucleophiles to the singlet nitrenium ions is reversible (cf: Scheme 22) thus, enhancing the probability of conversion or when conjugation in the singlet nitrenium ions is disturbed by steric effects (cJ Scheme 20) thus, destabilizing the singlet state relative to the triplet state.

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Studien Zum Ablauf Der Substitution XII. Umlagerung Und Thermischer Zerfall Acylierter Hydroxylamine

Cited by 41 publications

References 42 publications

Rearrangement of Differentially Protected N‐Arylhydroxylamines

Rearrangement of Differentially Protected N‐Arylhydroxylamines

N-Arylhydroxamic Acids as Novel Oxidoreductase Substrates

Zur Photochemie von 1H‐ und 2H‐Indazolen in saurer Lösung

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