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A novel approach for the synthesis of enamine derivatives of N-protected 3-acyltetramic acids is described. The synthetic procedure relies on α-C-acylation of β-enamino amides with N-protected α-amino acids and subsequent cyclisation of the obtained intermediates in refluxing TFA. The tetramic derivatives are obtained with very good enantiopurity (e.r. ≥95:5). Ring-enlarged analogues (piperidine-2,4-diones) can also be obtained from β-amino acids. 相似文献
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《Tetrahedron: Asymmetry》2000,11(5):1239-1248
For the first time, enzymatic resolution of α-azido acid amides has been successfully demonstrated with high yields and enantiomeric excess. In one case dynamic kinetic resolution was achieved leading to more than 50% yield of the enantiomerically pure azido acid. Chiral HPLC was also used to separate racemic α-azido acids and the separation process was automated. Two routes to enantiopure α-azido acid building blocks for solid-phase peptide synthesis have, therefore, been established. 相似文献
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Reaction of γ-dicarboxylic acids amides and imides with trifluoromethanesulfonamide and formaldehyde
M. Yu. Moskalik V. I. Meshcheryakov B. A. Shainyan 《Russian Journal of Organic Chemistry》2009,45(11):1644-1650
Three-component condensation of trifluoromethanesulfonamide with paraformaldehyde and succinamide depending on the reaction
conditions led alongside bis(trifluoromethanesulfonamido)methane to the formation of a substitution product, bis[(trifluoromethylsulfonyl)aminomethyl]succinamide,
or to a cyclization product, N-[trifluoromethylsulfonyl)aminomethyl]succinimide. The attempt to obtain the latter by the reaction of the trifluoromethanesulfonamide
sodium salt CF3SO2NHNa with N-chloromethylsuccinimide unexpectedly resulted in N,N-bis(succinimidomethyl)-trifluoromethanesulfonamide. Analogously the reaction of CF3SO2NHNa with N-chloromethyl-phthalimide gave N,N-bis(phthalimidomethyl)trifluoromethanesulfonamide. The reaction of CF3SO2NHNa with succinimide and phthalimide in water and alcohol solution resulted in the ring opening and further transformation
of the formed monosubstituted N-(trifluoromethylsulfonyl)amides of succinic and phthalic acids. 相似文献
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V. M. Lyubchanskaya L. S. Sarkisova L. M. Alekseeva V. G. Granik 《Chemistry of Heterocyclic Compounds》1992,28(3):299-303
The process of condensation of p-benzoquinone with the secondary cyclic enamines 2-(2-nitromethylene)pyrrolidine, -piperidine, and -hexahydroazepine is very much dependent on the size of the saturated ring in these compounds. With increasing ring size, the content of derivatives of 5-hydroxybenzofuran decreases, and the quantity of derivatives of 5-hydroxyindole increases; with the seven-membered enamine, a substituted 6-hydroxyindole is also formed. For enamines of the pyrrolidine and piperidine series, 1,4-bis-2-(2-nitromethylene)pyrrolidono- or piperidinohydroquinones are also recovered.For Communication 71, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 357–362, March, 1992. 相似文献
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Summary -(-Ethylhexoxy)-vinylphosphonic dichloride, diethyl, dipropyl, dibutyl, di-isobutyl, di-isoamyl, dihexyl, di-2-ethylhexyl, di-(methoxyethyl) and di(ethoxyethyl) esters of -(-ethylhexoxy)-vinylphosphonic acid, tetramethyldiamide, tetraethyldiamide and dipiperidide -(-ethylhexoxy)-vinylphosphonic acid were prepared and characterized. 相似文献
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Depending on the N-heterocyclic carbene catalyst utilized, α-unbranched aldehydes selectively provided amides, esters, or carboxylic acids through oxidation by NCS. The α-unbranched aldehyde underwent these reactions chemoselectively in the presence of an aromatic or α-branched aldehyde. 相似文献
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Fang YQ Bio MM Hansen KB Potter MS Clausen A 《Journal of the American Chemical Society》2010,132(44):15525-15527
A general inversion-stereospecific, N-selective alkylation of substituted 2-pyridones (and analogues), amides, and carbamates using chiral α-chloro- or bromocarboxylic acids in the presence of KOt-Bu (or KHMDS) and Mg(Ot-Bu)(2) is reported. The resulting α-chiral carboxylic acid products were isolated by crystallization in good chemical yields and in high ee (>90% ee). Mechanistic evidence suggests that the reaction proceeds through 2-pyridone O-coordinated Mg carboxylate intermediates, which afford the product through an intramolecular S(N)2 alkylation. 相似文献
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N-((S)-1-Phenylethyl)halofluoroethanamides have been investigated as precursors to N-protected α-fluoro-α-amino amides by nucleophilic displacement of halide with nitrogen nucleophiles such as potassium phthalimide, sodium succinimide, sodium glutarimide, trimethylamine and sodium azide. With single diastereoisomers of the iodofluoroethanamide, clean inversion of configuration occurs at room temperature, but subsequent epimerisation may occur as a result of the liberated iodide. The α-fluoro-α-amino amides made underwent a wide variety of reactions depending on conditions, but in many cases the carbon-fluorine bond was compromised. However, reacting trimethylamine and N-((S)-1-phenylethyl)iodofluoroethanamide gave the corresponding α-fluorobetaine amide, and subsequent acidic hydrolysis led to α-fluorobetaine as the first example of an ‘unprotected’ α-fluoroamino acid. 相似文献
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A novel and efficient protocol for the synthesis of α,β-unsaturated amides has been developed using catalytic amount of Cu(OAc)2 and TBHP as an available oxidant. Oxidative coupling of various unsaturated carboxylic acids with N,N-disubstituted formamides was examined to furnish the desired products in good yields. 相似文献
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Xukai Guan Dong An Guofeng Liu Heng Zhang Jigang Gao Tianyun Zhou Guangliang Zhang Suoqin Zhang 《Tetrahedron letters》2018,59(25):2418-2421
Chiral imidodiphosphoric acids were employed as catalysts for the enantioselective α-chlorination of β-keto esters and amides using NCS as the chlorine source, providing a series of optically active products with good to high enantioselectivities (74–95% ee) and excellent yields (92–99%). This represents the first report of the Brønsted acid catalyzed enantioselective α-chlorination of cyclic β-keto derivatives. 相似文献
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《中国科学:化学(英文版)》2017,(11)
Amide, as a ubiquitous functional group, is essential in various aspects of chemistry and biology. Although the history of studying amide is rich and fruitful, the synthetic application of amide is very limited due to the inertness of amide C–N bond. Recently,significant advances have been achieved towards the nickel-mediated C–N activation of amides. This approach allows a facile generation of acyl-nickel intermediates, and a number of unique transformations have been designed and realized based on the amide C–N bond activation. Focused on the catalytic transformation, this review summarizes and categorizes the recent advances on the synthetic applications of Ni-mediated C–N bond activation of amides. 相似文献
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The fact that amides and esters form less stable enolates than ketones might be seen as evidence that electrostatic stabilization is unimportant in these anions. However, ab initio molecular orbital calculations show that electrostatic stabilization does in fact lie beneath the competing resonance effect that causes the decrease in acidity. The electrostatic contribution is revealed by examining torsionally twisted amide and ester structures in which the pi resonance interactions are largely inhibited. These twisted amides and esters have greater enolate acidity than the corresponding ketones. Qualitatively similar behavior is observed with respect to protonation, such that twisted amides and esters are generally less basic than the reference ketones, in striking contrast to their behavior in the normal geometries. 相似文献
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An efficient sodium bicarbonate promoted aerobic oxidation reaction to prepare N-monosubstituted α-keto amides in the presence of n-tetrabutylammonium hydrogensulfate (TBAHS) was described. This reaction provides a very simple and convenient synthetic route to N-monosubstituted α-keto amides from easily available aryl- or heteroarylacetamides in good to high yields without using toxic reagents and harsh conditions. 相似文献
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R. Nurdinov E. E. Liepin'sh I. Ya. Kalvin'sh 《Chemistry of Heterocyclic Compounds》1993,29(11):1347-1351
By the interaction of L-proline, L-thioproline, pipecolic acid, tetrahydro-1,4-thiazine-3-carboxylic acid, and diastereomeric esters of tetrahydro-1,4-thiazine-3,5-dicarboxylic acid with methyl chloroformate, methyl propiolate, and acetylenecarboxylic acid, we have obtained N-alkoxycarbonyl and N-alkoxycarbonylalkenyl derivatives of -iminocarboxylic acids. By the reaction of N-methoxycarbonyltetrahydro-1,4-thiazine-3-carboxylic acid with hydrazine hydrate, we have obtained 8-amino-7,9-dioxo-4-thia-1,8-diazabicyclo[4.3.0]nonane.For communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1561–1566, November, 1993. 相似文献
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