ChemInform Abstract: SYNTH. UND KETO‐ENOL‐GLEICHGEWICHT VON BETA‐KETOESTERN

Jacquier, Robert; Petrus, C.; Petrus, Francoise; Verducci, Jean

doi:10.1002/chin.197005131

Cited by 12 publications

(17 citation statements)

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“…Indeed, as discussed above, for ail a-unsaturated, asubstituted ester the production of isoxazolidin-3-one is not favoured. However, after treatment with N-methylhydroxylamine a peak was observed with a mass spectrum displaying the following m/z ions: M + = 171 (23) and 142(100), 125(11), 114(29), 100(4), 88(10), 70 (14), 55 ( 13) corresponding to the compound depicted in Scheme 12.…”

Section: Formation Of N-methyl-2-isoxazolidin-hne From T-enevalproylgmentioning

confidence: 96%

Study of reactions induced by hydroxylamine treatment of esters of organic acids and of 3-ketoacids: Application to the study of urines from patients under valproate therapy

Libert

Draye

Hoof

et al. 1991

Biol. Mass Spectrom.

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Hydroxylamine used at alkaline pH as oximating agent in the search for organic aciduria by gas chromatography/mass spectrometry (GC/MS) induces other chemical reactions. Esters are partially transformed in their corresponding hydroxamic acids. GC/MS characteristics of the trimethylsilylated derivatives of the hydroxamic acids arising from alpha-unsaturated esters are here reported. Their mass spectral fragmentation helps in the recognition of peaks arising from the glucuronides of 2-ene- and probably 2,3'-diene-valproic acid. By heating in the injection port of the gas chromatograph, part of some trimethylsilylated hydroxamic acids are transformed to the corresponding isocyanates by a Lossen-like rearrangement. In addition to the corresponding hydroxamic acids, hydroxylamine treatment of alpha-unsaturated esters forms 2-isoxazolidin-3-ones by intramolecular Michael addition. GC/MS characteristics of the trimethylsilylated derivatives of these compounds are reported. Submitted to hydroxylamine, 3-ketoacids forms 2-isoxazolin-5-ones by cyclization of the oximes after acidification. This explains the existence of two GC peaks observed from urine extracts of patients under valproate therapy, which correspond to two tautomers of 2-isoxazolin-5-one originating from the oximes of the 3-keto-valproic acid.

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Section: Formation Of N-methyl-2-isoxazolidin-hne From T-enevalproylgmentioning

confidence: 96%

Study of reactions induced by hydroxylamine treatment of esters of organic acids and of 3-ketoacids: Application to the study of urines from patients under valproate therapy

Libert

Draye

Hoof

et al. 1991

Biol. Mass Spectrom.

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“…2 ) Among them, the reaction of [3- hydroxylamine, which seemed to be the most plausible and practical one, generally gave 3-isoxazolin-5-one (8), accompanied with 3-hydroxyisoxazoles (3) as the minor product, as reported by Jacquier et al 7 ) (Fig. 1).…”

mentioning

confidence: 52%

Synthesis of 3-Hydroxyisoxazoles fromγ-Ketoesters and Hydroxylamine

Sato

Sugai

Tomita

1986

Agricultural and Biological Chemistry

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“…On a small scale the 1 H and 13 C NMR monitoring of a reaction of 34 in neat trimethyl orthoacetate ( 3 ) shows the quick conversion of 34 in both N ‐ and O ‐methyl derivatives 35 and 36 in a 55:45 ratio. It is noteworthy that the reaction of diazomethane with 34 gives an identical result 19 …”

Section: Resultsmentioning

confidence: 83%

Methyl Orthocarboxylates as Methylating Agents of Heterocycles

et al. 2002

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Methylation reactions occurring between trimethyl orthocarboxylates or N,N‐dimethylcarboxamide dimethyl acetals and various hydroxylated heterocycles, involving a lactam‐lactim tautomeric equilibrium, were investigated as an alternative to classic methylation methods. The corresponding O‐methylated or N‐methylated compounds were isolated in a number of instances and the reaction’s regioselectivity was shown to sometimes follow and sometimes differ from the corresponding outcome using standard methylation methods. In the course of this work, previously unreported effects were noticed. In one case the use of toluene as a reaction solvent led to much more N‐methylated material. In other instances, the influence of the reagent’s steric bulk and/or stability (orthoformate vs. orthoacetate or N,N‐dimethylformamide dimethyl acetal vs. its acetamide homologue) was also noticed. An unwanted formylation reaction could sometimes be avoided and, less often, an increase of O‐methylated material was observed. The previously unreported 1‐dimethoxymethylpyridin‐2(1H)‐one was characterized and its acid‐catalyzed rearrangement into, mostly, 1‐methylpyridin‐2(1H)‐one was studied. The new techniques described here (methanol trapping with 4 Å molecular sieves and Lewis acid‐catalyzed reaction) greatly increase the potential of trimethyl orthocarboxylates. These reagents can be considered as possible alternatives to the dimethyl formamide‐producing N,N‐dimethylformamide dimethyl acetal and may sometimes be attractive options compared to the usual carcinogenic and salt‐producing methylating agents. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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ChemInform Abstract: SYNTH. UND KETO‐ENOL‐GLEICHGEWICHT VON BETA‐KETOESTERN

Abstract: Die Ketoester (I) reagieren in Gegenwart von Na‐äthylat mit den Halogeniden (II) zu den tautomeren Estern (III) und (IV) (35‐78% Ausbeute), daneben entstehen in l‐6%iger Ausbeute die entsprechenden O‐Alkylderivate.

Cited by 12 publications

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Study of reactions induced by hydroxylamine treatment of esters of organic acids and of 3-ketoacids: Application to the study of urines from patients under valproate therapy

Study of reactions induced by hydroxylamine treatment of esters of organic acids and of 3-ketoacids: Application to the study of urines from patients under valproate therapy

Synthesis of 3-Hydroxyisoxazoles fromγ-Ketoesters and Hydroxylamine

Methyl Orthocarboxylates as Methylating Agents of Heterocycles

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