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1.
M. N. Elinson S. K. Fedukovich Z. A. Starikova A. N. Vereshchagin P. A. Belyakov S. V. Gorbunov G. I. Nikishin 《Russian Chemical Bulletin》2006,55(1):106-111
Electrolysis of 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylic acid esters in alcohols in an undivided cell in the
presence of NaBr or NaOAc afforded 6-substituted (1R,5R, 6R)*-4,4-dialkoxy-5-cyano-2-oxo-3-azabicyclo[3.1.0]hexane-1-carboxylic acid esters in 80–95% yields.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 102–107, January, 2006. 相似文献
2.
The interaction of Me3SiOTf and (C6F5)3SiOTf with enamines generating α-silyl-substituted iminium ions is investigated. A trimethylsilyl iminium cation is formed as a long-lived species observable by NMR spectroscopy, whilst the tris(pentafluorophenyl)silyl analogue is very labile and prone to the loss of a proton. On the basis of the latter phenomenon, a method for the synthesis of β-silyl enamines is proposed. 相似文献
3.
A. V. Belyakov A. V. Golubinskii L. V. Vilkov V. I. Shiryaev E. M. Styopina E. A. Kovalyova V. S. Nikitin 《Russian Chemical Bulletin》1993,42(2):346-349
The molecular structure of gaseous Br2Sn(CH2SiMe2)2O was studied by electron diffraction. The six-membered ring has a chair conformation whereas the entire molecule possessesC
s
symmetry. The existence of a boat conformer cannot be completely excluded. The results of theoretical calculations for a twisted-boat conformation are at variance with the experimental data. Steric strain caused by mutual repulsion of the two axial methyl groups is reduced to the tilt of the Me2Si fragments in opposite directions. This results in an increase (up to 26°C) in the angle formed by the bisector of the CM-Si-CM angle with the CcSiO plane. The main geometrical parameters are as follows:r
g (Å): Si-O 1.708(20); Si-CM 1.862(20); Si-Cc 1.882(9); Sn-C 2.108(26); Sn-Br 2.456(3); C-H 1.099(30); (degr.): C-Sn-C 105(2); Br-Sn-Br 107.9(1.2); Si-O-Si 129.6(3); CM-Si-CM 112; Si-C-H 113 (fixed value in accordance with experiment); Cc-Si-O 107(2); Sn-C-Si 109(2); torsion angles: (Si-C) 52(2); (Si-O) 62(1); (Cc-Sn) 54(1). The average amplitudes were fixed at the values calculated from the force field. Structural parameters of molecules with similar structures were analyzed and compared.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 384–387, February, 1993. 相似文献
4.
5.
Ten unsymmetrically substituted arylamino-1,3,5-triazines were synthesized and studied by dynamic NMR spectroscopy. The free energies of the hindered rotation ΔG≠?are in 59–77 kJ mol? 1 range. Using difference-mode NOE NMR experiments, the structures of the major and minor rotation isomers were proved. The DFT B3LYP/6-31G* calculations were performed. The difference between the calculated rotation barriers and the experimental values obtained by line shape analysis is less than 7.6 kJ mol?1. The height of the rotation barrier varies in a 18 kJ mol?1 range depending on the substituents in the triazine ring. 相似文献
6.
I. Iovel L. Golomba S. Belyakov J. Popelis E. Lukevics 《Chemistry of Heterocyclic Compounds》2003,39(11):1443-1453
The reactions of 4-nitrocinnamaldehyde with trifluoromethylanilines in the presence of molecular sieves were studied, and a series of new aromatic and heterocyclic aldimines were synthesized. The molecular and crystal structure of some of them were determined by X-ray crystallographic analysis. 相似文献
7.
Alexander D Dilman Pavel A Belyakov Vladimir A Tartakovsky 《Tetrahedron letters》2004,45(19):3741-3744
Silyl enol ethers bearing three pentafluorophenyl groups at the silicon atom are described. These compounds undergo uncatalyzed aldol reactions with aliphatic, α,β-unsaturated, and aromatic aldehydes. The observed reactivity is analyzed in terms of the Lewis acidity of the silyl fragment. 相似文献
8.
A.V. Belyakov L.S. Khaikin L.V. Vilkov E.T. Bogoradovsku V.S. Zavgorodnii 《Journal of Molecular Structure》1981
The geometrical parameters of the tetraphenyltin molecule have been determined by gas phase electron diffraction at about 310°. The S4 and “open” D2d molecular models with the tetrahedral bond configuration at tin were chosen for the structure analysis. The former gave the better fit. The thermal average bond lengths (rg, in Å) are as follows: The benzene ring geometry appears to be almost unaffected by bonding to tin. However, tin causes an increase in the endocyclic valence angle at the ipso-carbon atom to 121.0(0.9)° rather than a decrease of that angle as might be expected, tin being a σ-electron donor. The ring plane and the plane containing the bond and S4 axis make an angle, ?, of 34.1(2.1)°. The bond length in tetraphenyltin is longer than not only the bond in tetravinyltin (rg = 2.117(4) Å) but also the bond in tetramethyltin (rg = 2.144(7) A). 相似文献
9.
L.S. Khaikin A.V. Belyakov L.V. Vilkov E.T. Bogoradovskii V.S. Zavgorodnii 《Journal of Molecular Structure》1980
The geometrical parameters of tetraethynyltin and triethynyltin iodide have been determined by gas-phase electron diffraction. Triethynyltin iodide was present as an admixture in both the tetraethynyltin samples studied. Because the samples differed significantly in percentage of the iodide (17.4 ± 4.0 and 47.1 ± 3.5 mol %, in samples A and B, respectively), it was possible to determine the structures of both molecules to a sufficient degree of accuracy.The rα, structures were solved by the least-squares treatment of the molecular intensities, using mean amplitudes and shrinkage corrections calculated from the force fields of a number of tin derivatives.The Td-symmetry model of Sn(CCH)4 was refined to give the following parameters: Sn-C, 2.068(5); CC, 1.228(8); CH, 1.079(51). The structural parameters for ISn(CCH)3 (on the basis of the C3v model with linear Sn-CC-H fragments) are as follows: Sn-I, 2.646(4); Sn-C, 2.062(17); CC, 1.226(6); ∠ISnC 108.0(2.8). (The thermal average bond distances, rg, are given in Å, and the valence angle, rα, in degrees; the values in paren- theses are three times the standard deviations, 3σ.)The Sn-C bonds in Sn(CCH)4, and ISn(CCH)3 are shorter than the corresponding bonds in the monoethynyltin derivatives, Me3SnCCH and Me3SnCCSnMe3. The SnI bond in ISn(CCH)3 is noticeably shorter than those in stannane iodide and trimethylstannane iodide. 相似文献
10.
A. V. Eremeev R. Nurdinov F. D. Polyak R. M. Zolotoyabko A. F. Mishnev S. V. Belyakov Ya. Ya. Bleidelis 《Chemistry of Heterocyclic Compounds》1986,22(9):1039-1044
1-Aza-3-oxa-7-thiabicyclo[3.4.0]nonan-2-one was obtained by reduction of 3,4-dimethoxycarbonyltetrahydro-1,4-thiazine. The reduction of this product with lithium aluminum hydride led to 3-hydroxymethyl-4-methyltetrahydro-1,4-thiazine. The molecular and crystal structures of 1-aza-3-oxa-7-thiabicyclo[3.4.0]nonan-2-one were investigated by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1280–1285, September, 1986. 相似文献