- Acid promoted dimerization of β-amino-α,β-unsaturated amides affording bis(functionalized) pyrrolinones
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Polysubstituted pyrrolinones were synthesized by the dimerization of 3-amino-2-butenamides via treatment with 0.5 equiv p-TsOH under mild reaction conditions, including oxidation and 1,2-migration of the methyl group. This method is practically advantageo
- Hirai, Sho,Asahara, Haruyasu,Nishiwaki, Nagatoshi
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- Zinc carbenoid-mediated chain extension of β-keto amides
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The reaction of β-keto amides with ethyl(iodomethyl)zinc provides access to a wide variety of γ-keto amides, including primary, secondary, and tertiary amides. Although the reaction of α-substituted β-keto amides are in many cases unsatisfactory, the method can be applied to a broad spectrum of substrates that possess imide and olefinic functionality.
- Hilgenkamp, Ramona,Zercher, Charles K
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p. 8793 - 8800
(2007/10/03)
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- Syntheses of 5-(alkylaminocarbonyl)-4,6-dimethyl-2-pyridones from N- alkyl-3-oxobutanamides
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1-Alkyl-5-(alkylaminocarbonyl)-4,6-dimethyl-2-pyridones were obtained in high yields from the self-condensation of N-alkyl-3-oxobutanamides in the presence of p-toluenesulfonic acid as a catalyst at 100-110°C for 11-24 hours without solvent.
- Furukawa, Isao,Fujisawa, Hironori,Kawazome, Mitsuru,Nakai, Yasuto,Ohta, Tetsuo
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p. 1715 - 1717
(2007/10/03)
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- Synthesis of heterocyclic systems with carbohydrate fragment: 2. Stereoselective synthesis of tetrahydropyridones by reaction of levoglucosenone with amides of α-methylene-active acids
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The reactions of levoglucosenone with amides of several α-nitrocarboxylic acids and acetoacetic acid result in tetrahydropyridones fused with a carbohydrate fragment. In the case of acetoacetic acid amides, mixtures of keto and enol tautomers were obtained. The stereochemistry of cyclization is discussed in detail.
- Samet,Kislyi,Chernyshova,Reznikov,Ugrak,Semenov
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p. 393 - 398
(2007/10/03)
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- Lipase-catalyzed aminolysis and ammonolysis of β-ketoesters. Synthesis of optically active β-ketoamides.
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Aminolysis and ammonolysis reactions of β-ketoesters catalyzed by Candida antarctica lipase are very efficient methods for the preparation of β- ketoamides. When racemic amines are used in these processes, the corresponding optically active β-ketoamides are obtained with moderate-high enantiomeric excesses.
- Garcia,Rebolledo,Gotor
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p. 6935 - 6940
(2007/10/02)
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- Reactions of β-Ketoamides. Part 1. Kinetics of Enolisation of Acetoacetamide in Water and of Acetoacetamide and Acetoacetanilide in Ethanol-Water
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Kinetic results are reported for the rates of enolisation (ke) of acetoacetamide in water and for acetoacetamide and acetoacetanilide in ethanol-water (70:30 v/v) as measured by their rates of halogenation.The effects of nickel(II), zinc(II) and acetate on the rates of enolisation are also described.Unlike β-diketones, the enolisation of β-ketoamides is acid catalysed.The rates of ketonisation (kf) of the two β-ketoamides have been also investigated using stopped-flow spectrophotometry.The keto:enol ratios have been derived using the experimentally measured ke and kf values.
- Hynes, Michael J.,Clarke, Eve M.
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p. 901 - 904
(2007/10/02)
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- Chemoenzymatic aminolysis and ammonolysis of β-ketoesters
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Candida antarctica lipase efficiently catalyses the preparation of β-ketoamides from β-ketoesters with primary aliphatic amines and ammonia.
- Garcia, Maria Jesus,Rebolledo, Francisca,Gotor, Vicente
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p. 6141 - 6142
(2007/10/02)
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- Acidity and tautomerism of β-keto esters and amides in aqueous solution
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The pH-rate profiles for the keto-enol tautomerization of 17 β-keto esters and amides (RCOCH2COX: R = methyl; phenyl; 2-, 3-, and 4-pyridyl; 3(and 4)-(N-methylpyridinio); X = OCH3, OC2H5, NH2, or N(CH3)2) have been measured by stopped-flow spectrophotometry in aqueous solution (ionic strength 0.1, 25 °C) over the range pH = 2-12. Analysis of these profiles gives the microscopic rate constants for ketonization and enolization of each of these species in these aqueous solutions. Analysis of the pH dependence of the buffer catalysis for the general-acid-catalyzed protonation of these enolate conjugate bases allowed the evaluation of paE for the deprotonation of each enol species. In combination with pKaeq, these data in turn allow the calculation of the acidities of the keto tautomers (pKaK) and the equilibrium constants for enolization (KE = [enol]/[keto] ). In all cases, both the keto and enol tautomers of the amides are more acidic than the corresponding ester derivatives. The equilibrium enol/keto ratios (KE) were found to decrease in the order: 2-pyridyl > 4-pyridyl > 3-pyridyl > 4-(N-methylpyridinio) > 3-(N-methylpyridinio) > methyl ≈ phenyl for both β-keto esters and amides. A simple linear correlation between pKaE and pKaKwas observed for these series of β-keto esters and amides. Bronsted plots of second-order rate constants for deprotonation of the keto tautomer as a function of keto tautomer acidity were found to be linear, with a values in the range 0.37-0.54 for hydroxide ion, acetate ion, and several amine bases. However, the "water-catalyzed" reaction is unusual with Br?nsted α = -0.17. This α value is only readily explicable in terms of a combined general acid + general base catalysis involving two water molecules for the equilibration of the keto tautomer and the neutral enol species.
- Bunting, John W.,Kanter, James P.
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p. 11705 - 11715
(2007/10/02)
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- Inhibitors of the advanced glycosylation of proteins and methods of use therefor
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The present invention relates to compositions and methods for inhibiting nonenzymatic cross-linking (protein aging). Accordingly, a composition is disclosed which comprises an agent capable of inhibiting the formation of advanced glycosylation endproducts of target proteins by reacting with a carbonyl moiety of an early glycosylation product of such target proteins resulting from their initial glycosylation. The method comprises contacting the target protein with the composition. Both industrial and therapeutic applications for the invention are envisioned, as food spoilage and animal protein aging can be treated.
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- Inhibitors of the advanced glycosylation of proteins and methods of use therefor
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The present invention relates to compositions and methods for inhibiting nonenzymatic cross-linking (protein aging). Accordingly, a composition is disclosed which comprises an agent capable of inhibiting the formation of advanced glycosylation endproducts of target proteins by reacting with the carbonyl moiety of the early glycosylation product of such target proteins formed by their initial glycosylatin. The method comprises contacting the target protein with the composition. Both industrial and therapeutic applications for the invention are envisioned, as food spoilage and animal protein aging can be treated.
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- HYDROLYSE BASIQUE ET DECARBOXYLATION D'ESTERS ALLOPHANIQUES EN MILIEU MIXTE ACETONITRILE-EAU: CATALYSE BIFONCTIONNELLE PAR UNE ENTITE FORMEE ENTRE BASE ET SOLVANT
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Base catalysed hydrolysis of allophanic esters-models of carboxybiotine- in acetonitrile/water mixture, shows a sharp increase in rate constant in the range of 0.1-0.3 M in water, with a maximum which is interpreted as a balance between two desolvation terms, one concerning the nucleophile, the other the anionic transition state.Moreover, in acetonitrile/water mixtures at low water content (2.10-2 M), a fast hydrolysis (kexpca.0.5 s-1 at 20 deg C) of allophanic esters (carboxy-biotin models) is observed due to catalysis by the enolate of acetamide.This speciesalso catalyses the decarboxylation step, likely behaving as a bifunctional catalyst.
- Monnier, E.,Klaebe, A,Perie, J. J.
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p. 3067 - 3070
(2007/10/02)
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