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[reaction: see text] An efficient and stereospecific approach to the synthesis of structurally constrained aza-, oxa-, and thiabicyclo[3.1.0]hexane heterocycles has been achieved through application of the intramolecular cyclopropanation reaction of diazoacetates. The various constrained heterocycles (X = N, O, or S) are conveniently prepared from a common diol intermediate accessible from readily available cinnamyl alcohols. Application of the methodology to the synthesis of conformationally constrained oxazolidinone antibacterials is also discussed. 相似文献
14.
A. D. Gordeev I. A. Kyuntsel V. A. Mokeeva G. B. Soifer V. V. Shchepin 《Journal of Structural Chemistry》1994,35(2):195-200
Temperature dependences of35Cl NQR frequencies and spin-lattice relaxation times were measured for the CCl3 groups of compounds CCl3CH=CHR and CCl3CH=CR2 with R=COCH3 and COOCH3. The activation energies of CCl3 reorientations reflect the significant contribution of intermolecular steric interactions to the value of the potential barrier
hindering these reorientations. In the CCl3CH=CHCOCH3 crystal, the reorientations of the CCl3 group are hindered more than those of the molecule as a whole.
Perm State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 2, pp. 54–60, March–April, 1994.
Translated by L. Smolina 相似文献
15.
Apparent two-dimensional behavior of TiO2 nanotubes revealed by light absorption and luminescence 总被引:1,自引:0,他引:1
Bavykin DV Gordeev SN Moskalenko AV Lapkin AA Walsh FC 《The journal of physical chemistry. B》2005,109(18):8565-8569
Optical absorption and photoluminescence (PL) properties of colloidal TiO(2) nanotubes, produced by the alkali hydrothermal method, were studied at room temperature in the range 300-700 nm. Nanotubes having an internal diameter in the range 2.5-5 nm have very similar optical properties, in contrast to the expected behavior for quasi-1-D systems. This is explained by the complete thermal smearing of all 1-D effects, due to the large effective mass of charge carriers in TiO(2), resulting in an apparent 2-D behavior of TiO(2) nanotubes. 相似文献
16.
Sh. A. Samsoniya D. O. Kadzhrishvili E. N. Gordeev V. E. Zhigachev L. N. Kurkovskaya N. N. Suvorov 《Chemistry of Heterocyclic Compounds》1982,18(4):382-385
Ethyl pyruvate 1-acetyl-5-indolinylhydrazone was obtained by diazotization of 1-acetyl-5-aminoindoline with subsequent reduction of the diazonium salt and condensation of the hydrazine with ethyl pyruvate. A mixture of hydrogenated derivatives of linear and angular pyrroloindoles is formed as a result of cyclization of the hydrazone in polyphosphoric acid esters. Subsequent hydrolysis, decarboxylation, and dehydrogenation lead to 1H,5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo-[3,2-e]indole.See [1] for Communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 504–507, April, 1982. 相似文献
17.
β-Aminopropionohydroxamic acid reacts with aliphatic aldehydes or ketones to give 2-substituted 1-hydroxytetrahydropyrimidin-6-ones,
while its reaction with aromatic carbonyl compounds leads to either the same products or Schiff's bases, which can exist in
tautomeric equilibrium in solution.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 691–694, April, 1998. 相似文献
18.
Daniil A. Boiko Evgeniy O. Pentsak Vera A. Cherepanova Evgeniy G. Gordeev Valentine P. Ananikov 《Chemical science》2021,12(21):7428
Smoothness/defectiveness of the carbon material surface is a key issue for many applications, spanning from electronics to reinforced materials, adsorbents and catalysis. Several surface defects cannot be observed with conventional analytic techniques, thus requiring the development of a new imaging approach. Here, we evaluate a convenient method for mapping such “hidden” defects on the surface of carbon materials using 1–5 nm metal nanoparticles as markers. A direct relationship between the presence of defects and the ordering of nanoparticles was studied experimentally and modeled using quantum chemistry calculations and Monte Carlo simulations. An automated pipeline for analyzing microscopic images is described: the degree of smoothness of experimental images was determined by a classification neural network, and then the images were searched for specific types of defects using a segmentation neural network. An informative set of features was generated from both networks: high-dimensional embeddings of image patches and statics of defect distribution.Defectiveness of carbon material surface is a key issue for many applications. Pd-nanoparticle SEM imaging was used to highlight “hidden” defects and analyzed by neural networks to solve order/disorder classification and defect segmentation tasks. 相似文献
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The quadrupole resonance spectra and the quadrupole spin-lattice relaxation times of the35Cl nuclei are correlated with the molecular structures of the two chlorine-containing diazadienes CCl3CCl=NCCl=NC6H5 and CCl3CCl=NCCl=NCCl2CCl3. The monotropic polymorphism found in the case of the second crystal is discussed.Perm State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 84–87, March–April, 1993. 相似文献