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S. V. Shorshnev S. E. Esipov A. I. Chernyshev 《Chemistry of Heterocyclic Compounds》1988,24(11):1271-1277
On the basis of an analysis of the changes in the chemical shifts of the signals in the1H and13C NMR spectra on the pyrimidotriazinedione and trifluoric acid concentrations in CDCl3 it was established that the protonation of rheumycin and fervenulin takes place at the N(2) atom, whereas the protonation of isofervenulin takes place competitively at the N(1), N(2), and O(6) atoms. The equilibrium constants of the investigated protonation processes were measured.A study of the chemical peculiarities of the behavior of Ia, b in aqueous acidic media (H2O-HCl, D2O-DCl) was described in [6].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1532–1538, November, 1988. 相似文献
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I. S. Poddubnyi L. I. Belen'kii M. I. Struchkova M. M. Krayushkin 《Chemistry of Heterocyclic Compounds》1994,30(6):729-737
The1H and13C NMR spectra of 2, 5-disubstituted 1,3,4-oxadiazoles with aliphatic, aromatic, and hetero-aromatic substituents have been described and interpreted. The electronic effect of the 1,3,4-oxadiazole group as a benzene ring substituent was evaluated using13C NMR spectroscopy.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 834–842, June, 1994. Original article submitted April 8, 1994. 相似文献
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The stereochemistry of various pairs of isomeric 2-cyclohexen-1-ylidenecyanoacetates was assigned using 1H NMR spectroscopy. The isomers with the γ-methylene or the γ-vinyl protons cis to the carbalkoxy group were found to have the signals of these protons at approximately 0.3 ppm and 1 ppm, respectively, downfield relative to their geometrical isomers or the corresponding 2-cyclohexen-1-ylidenemalononitriles. The observation regarding the γ-vinyl proton proved useful for the assignment of configuration to cyclohex-enylidenecyanoacetates derived form cholest-4-en-3-one. The large and constant downfield shift (c. 1 ppm) of the γ-vinyl proton when cis to the ester group results from the rigid cyclohexenylidenecyanoacetate system, in which the vinylic proton can approach more closely to the magnetically anisotropic ester carbonyl group. 相似文献
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A. V. Afonin L. A. Es'kova V. K. Voronov E. S. Domnina L. V. Baikalova E. V. Petrova 《Chemistry of Heterocyclic Compounds》1988,24(4):410-412
Analysis of 1H and 13C NMR spectral parameters for 1-vinylbenzazoles has shown that the vinyl group has a predominantly trans orientation with respect to the condensed benzene ring. Additional evidence is given for a long range effect of the nitrogen lone pair electrons on the one bond 13C-1H and 1H-1H spin-spin couplings and on the 1H chemical shifts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 499–501, April, 1988. 相似文献
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A series of thirteen 15N-enriched N-aryl imines derived from benzaldehydes and acetophenones have been prepared and examined by 13C and 1H NMR. Preferred conformations of the C-arvl and N-aryl rings have been deduced from 13C chemical shifts and 13C-15N couplings. Evidence for steric inhibition of resonance in O-alkylated materials is presented. Relative signs of 1J(CN) and 2J(CCN) have been determined in some compounds. An E: Z interconversion barrier of 21.6 kcal mol?1 has been obtained from 1H NMR coalescence data. 相似文献
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A. V. Afonin B. V. Trzhtsinskaya E. V. Apakina 《Chemistry of Heterocyclic Compounds》1991,27(3):296-299
Quantitative evaluations of the percentages of rotational isomers in 1-vinyl-1,2,4-triazoles were obtained. The population of the s-cis(N(2)) form in 1-vinyl-1,2,4-triazole is greater by a factor of two than in the s-trans form.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 365–368, March, 1991. 相似文献
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Benzotriazole nitro derivatives were prepared by nitration of the corresponding benzotriazoles and by methylation or cyclization of appropriate nitro‐1,2‐phenylenediamines. Structures and tautomerism of the nitrobenzotriazoles were studied by multinuclear 1H, 13C, 15N, and 2D NMR spectroscopy and quantum chemistry. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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V. A. Denisenko V. L. Novikov A. V. Kamernitskii G. B. Elyakov 《Russian Chemical Bulletin》1977,26(6):1317-1319
Conclusions The combined use of the1H and13C NMR spectra makes it possible to unequivocally assign 1-methyl-4-octalin-l,2-dicarboxylic acids and their derivatives to the proper steric series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1429–1431, June, 1977. 相似文献
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Conclusions The 3-0- and 4-0-trityl ethers of the acetates of methyl -L- arid methyl -L-arabinopyranosides were synthesized. The glycosylation of the ethers with the aid of 3,4-di-0-acetyl-1,2-0-(1-exo-cyano)ethylidene--L-arabinopyranose and the subsequent deacetylation of the synthesized products yielded the disaccharides: methyl 4-0-(-L-arabinopyranosyl)-,methyl 4-0-(-L-arabinopyranosyl)-, and methyl 3-0-(-L-arabinopyranosyl)--L-arabinopyranoside; and methyl 4-0-(-L-arabinopyranosyl)-, methyl 4-0-(-L-arabinopyranosyl)-, methyl 3-0-(-L-arabinopyranosyl)-, and methyl 3-0-(-L-arabinopyranosyl)--L-arabinopyranoside.The assignment of the signals in the PMR and13C NMR spectra of the synthesized arabinopyranosyl biosides was carried out, allowing the determination of the type and configuration of the glycosidic bond by means of which the arabinopyranose residues are linked in the oligo- and polysaccharide chains.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 200–209, January, 1986. 相似文献
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Alexander Búcsi Janka Karlovská Michal Chovan Ferdinand Devínsky Daniela Uhríková 《Chemical Papers》2014,68(6):842-846
The pK a values of N-alkyl-N,N-dimethylamine-N-oxides were determined from the pH dependences of chemical shifts in 1H NMR and 13C NMR spectra. The dependences were measured at concentrations below and above the critical micelle concentration of the amine oxides. Above the critical micelle concentration, the plots of the peak positions vs. pH were either sigmoid (the groups close to the nitrogen) or “peak type” (farther groups). The sigmoidal behaviour was a direct result of the acid-base reaction; on the other hand, the “peak type” behaviour was probably an indirect consequence of the pH variation, mediated with the change in micelle size. 相似文献
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V. A. Denisenko V. L. Novikov V. V. Isakov A. V. Kamernitskii G. B. Elyakov 《Russian Chemical Bulletin》1976,25(8):1782-1784
Conclusions The combined use of the1H and13C NMR spectra makes it possible to unequivocally assign the 1,4,5-trimethyl-4-cyclohexene-1,2-dicarboxylic acids and their derivatives to a given steric series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1892–1894, August, 1976. 相似文献
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The 13C and 1H NMR spectra of a series of methiodides of mono- and di-C-methyl derivatives of 1-methyl-4-phenyl-4-piperidinols are reported and chemical shift data analysed in terms of configurations and conformations of isomeric sets. Results demondtrate the value of quaternary salt NMR data as an aid to configurational assignment, and the evaluation of non-bonded interactions governing conformational equilibria in piperidine derivatives. 相似文献
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V. P. Lezina S. G. Rozenberg O. M. Glozman L. A. Zhmurenko L. M. Meshcheryakova V. A. Zagorevskii 《Chemistry of Heterocyclic Compounds》1990,26(2):172-178
The 1H and 13C NMR spectra of the E and Z isomers of 2-, 3-, and 4-benzoylpyridine oximes and their ethers were analyzed thoroughly, and the 1H-13C spin-spin coupling constants (SSCC) were determined. It was established that the magnitude of the effect for the quaternary carbon atoms in the E and Z isomers depends on the site of substitution in the pyridine ring. It was assumed that the intermolecular hydrogen bond is stronger in the E form than in the Z form. The existence of the Z isomer of 2-benzoylpyridine oxime in deuterochloroform with an intramolecular hydrogen bond was proved.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 203–208, February, 1990. 相似文献
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《Tetrahedron》1987,43(8):1943-1948
The cis-1,3-disubstituted tetrahydroisoquinolines 2 can be obtained in a highly diastereoselective fashion through Pictet-Spengler cyclization of the 1,2-bis(3,4-dimethoxyphenyl)-ethylamine with aliphatic and aromatic aldehydes under acidic conditions. However, the epimeric trans-1,3-disubstituted tetrahydroisoquinolines 3 are also isolated as minor products. The stereochemistry of the tetrahydroisoquinolines was unambiguously assigned on the basis of the1H NMR data, and are supported by difference NOE measurements. 相似文献
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Lutnaes BF Luthe G Brinkman UA Johansen JE Krane J 《Magnetic resonance in chemistry : MRC》2005,43(7):588-594
Monofluorinated polycyclic aromatic hydrocarbons (F-PAHs) have attracted much attention in analytical, environmental, toxicological and mechanistic studies because of their physico-chemical properties, which are closely similar to those of the parent PAHs. Because of this, full NMR characterization has become of interest. Complete 1H, 13C and 19F NMR chemical shifts, and also 1J(H,C), (n)J(C,F), (n)J(H,F) and (n)J(H,H) coupling constants, have been assigned for the F-PAHs 1-fluoronaphthalene, 2-fluorofluorene, 5-fluoroacenaphthylene, 2-fluorophenanthrene, 3-fluorophenanthrene, 3-fluorofluoranthene, 1-fluoropyrene, 1-fluorochrysene, 2-fluorochrysene, 3-fluorochrysene and 9-fluorobenzo[k]fluoranthene. To allow comparison with the corresponding parent PAHs, the 1H and 13C chemical shifts of acenaphthylene, phenanthrene, fluoranthene, pyrene and benzo[k]fluoranthene were determined. Chemical shift increments and the effects on the coupling constants from the fluorine substitution are discussed. 相似文献
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Several pyridazin-3(2H)-one derivatives were synthesized starting from alkyl furans using oxidation with singlet oxygen to give 4-methoxy or 4-hydroxybutenolides, key intermediates of the synthetic strategy followed. For all pyridazinones reported, a complete assignment of the (1)H and (13)C NMR spectra using one- and two-dimensional NMR spectroscopic methods, which included NOE, DEPT, COSY, HSQC and HMBC experiments, was accomplished. Correlations between the chemical shifts of the heterocyclic ring atoms and substituents at N-2 and C-6 were analyzed. 相似文献
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The configuration and stable conformation of two dibenzylidene-L -iditol isomers formed upon benzalation of L -iditol, as well as that of a third isomer obtained by partial hydrolysis of the tribenzylidene derivative—the main product of the benzalation reaction—were determined by 1H and 13C NMR spectroscopy. 相似文献