- Intramolecular vinylation of carbanions using N-acyl benzomorpholines as masked vinylureas and vinylcarbamates
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Treatment of urea or carbamate derived benzomorpholines with lithium diisopropylamide generates N-vinyl ureas or N-vinyl carbamates by elimination of a phenoxide anion, cleaving the benzomorpholine ring. Simultaneous formation of a carbanion α to a stabilising aryl or nitrile group allows migration of the newly formed N-vinyl substituent to the carbanionic centre, in some cases with high enantiospecificity. Mild hydrolysis of the resulting urea or carbamate returns a C-vinylated amine, alcohol or hydantoin, in some cases with high enantiomeric purity. This ‘masked’ vinylation strategy avoids the need to use the reactive and volatile vinyl isocyanate as a starting material.
- Corbet, Brian P.,Matlock, Johnathan V.,Mas-Roselló, Josep,Clayden, Jonathan
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p. 634 - 642
(2017/05/24)
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- Design, synthesis and antioxidant properties of ovothiol-derived 4-mercaptoimidazoles
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Fourteen 4-mercaptoimidazoles derived from the naturally occurring family of antioxidants, the ovothiols, have been synthesized by cyclization of thioamides with trimethylsilyl trifluoromethane-sulfonate (triflate). These compounds have been assayed for their radical-scavenging activity.
- Zoete, Vincent,Bailly, Fabrice,Catteau, Jean-Pierre,Bernier, Jean-Luc
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p. 2983 - 2988
(2007/10/03)
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- α-Aminonitrile hydration in the presence of hydrogen peroxide in aqueous basic medium
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α-Aminonitriles are hydrated into α-aminoamides in the presence of hydrogen peroxide in sodic or ammoniacal basic medium. While the hydration mechanism is close to the mechanism described previously in the case of aromatic nitrites, we showed that, in weakly basic conditions, the amine function of α-aminonitrile is competitively oxidized via a peroxyimidic acid by an intramolecular process. In the case of 2-aminopropanenitrile, this reaction leads to pyruvamide oxime. Furthermore, the study of structurereactivity relationships in the hydration of aliphatic and aromatic monofunctional nitriles and α-aminonitriles showed that the reactivity of the substrates towards hydroperoxide onion, which mostly depends on inductive effects of the substituents, is sufficiently enhanced to allow hydration of tertiary α-aminonitriles with low steric hindrance and regioselective hydration of dissymmetric α-aminodinitriles. Eisevier,.
- Taillades, Jacques
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- Interaction α-aminoamide - compose carbonyle. Mecanisme de formation des imidazolidinones-4
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The reaction of α-N-methylaminopropionamide 1 with formaldehyde was studied in unbuffered aqueous solution.The reaction led to 1,5-dimethyl-4 imidazolidinone, 2a, in equilibrium with 3-hydroxymethyl 1,5-dimethyl 4-imidazolidinone, 3a, formed by addition of a second formaldehyde molecule.A kinetic study of the formation of 2a and 3a indicated that the addition of the amino group of 1 was a complete equilibrium.The reaction pathway involved the rate determining attack of the amide group of 1 on formaldehyde to form a hydroxymethyl amide intermediate, which was not isolated.The intramolecular assistance by the amino group, noted for this step, was interpreted as an attack of 1 in a zwitterionic form.Secondary amines catalyzed the formation of 2a and 3a by a pathway which involved the intermediate formation of iminium ions >N=CH2(1+).
- Pascal, R.,Lasperas, M.,Taillades, J.,Commeyras, A.,Perez-Rubalcaba, A.
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p. 329 - 337
(2007/10/02)
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- SYSTEMES DE STRECKER ET APPARENTES - XI FORMATION ET STABILITE DE L'α-CARBOXYAMINONITRILE. INTERMEDIAIRE ESSENTIEL DANS LA SYNTHESE DES HYDANTOINES SELON BUCHERER-BERGS
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The determination of the structure of the intermediate in the Bucherer-Bergs reaction (the transformation in aqueous solution of an aldehyde into the corresponding amino-acid via the hydantoin) showed that this reaction involved the formation of α-aminonitrile carbamate.The slow formation of the carbonic anhydride from the carbonate buffer limited the formation of that main intermediate which was in equilibrium with the α-aminonitrile.The variation of the stability of the carbamate vs pH is mainly determined by the concentration of CO2 dissolved in the mixture, but also by the equilibrated formation of products formed by the degradation of α-aminonitrile, i.e. the aminodinitrile and the cyanohydrin.
- Rousset, A.,Lasperas, M.,Taillades, J.,Commeyras, A.
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p. 2649 - 2661
(2007/10/02)
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