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81.
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83.
I. V. Vystorop N. P. Konovalova Yu. V. Nelyubina V. N. Varfolomeev B. S. Fedorov T. E. Sashenkova E. N. Berseneva K. A. Lyssenko R. G. Kostyanovsky 《Russian Chemical Bulletin》2010,59(1):127-135
The reactions of glycine hydroxamic and DL-alanine hydroxamic acids with triacetonamine are chemoselective and afford 1-hydroxy-7,7,9,9-tetramethyl-1,4,8-triazaspiro[4.5]decan-2-one
(3) and (±)-1-hydroxy-3,7,7,9,9-pentamethyl-1,4,8-triazaspiro[4.5]decan-2-one (4), respectively. The X-ray diffraction study showed that compound 3 crystallizes as a solvate with MeCN (1: 1). As shown by ESR measurements, spiro hydroxamic acids 3 and 4 are NO donors in in vitro biological systems. The NO-donor activity of compounds 3 and 4 was found to be substantially higher in the presence of DMSO. Homologue 4 is a stronger NO donor than 3. Compound 4 also exhibits high antimetastatic activity (81%) on the B16-melanoma model. 相似文献
84.
Lenev DA Lyssenko KA Golovanov DG Buss V Kostyanovsky RG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(24):6412-6418
We have shown through racemization kinetics studies that the enantiomerization barriers of the bis‐ortho‐methyl substituted Tröger bases 2 and 3 in acidic media are raised by 30 kJ mol?1 relative to the parent compound 1 , that is 130.4(4) and 131.6(4) kJ mol?1, respectively (105 °C, pH 1, ethylene glycol). The enantiomerization barrier of para‐methoxy‐para‐nitro substituted Tröger base 4 was determined by dynamic capillary electrophoresis to 96.3(2) kJ mol?1 (25 °C, pH 2.2, H2O), which is lower by 5 kJ mol?1 relative to 1 . The influence of deutero‐substitution on the racemization rates was also studied. The influence of steric and electronic factors on the enantiomerization barrier was investigated by quantum‐mechanical (DFT) calculations. It is shown that enantiomerization takes place in two steps: ring‐opening and further interconversion of the monocyclic intermediate. For the interconversion to occur a transition state has to be passed which is sensitive to steric effects. Ortho‐substitution by methyl groups significantly increases the energy of this state. Thus, compounds 2 and 3 are the simplest Tröger bases which are configurationally stable in acidic media. 相似文献
85.
Denis A. Lenev Konstantin A. Lyssenko Oleg R. Malyshev Remir G. Kostyanovsky 《Tetrahedron letters》2006,47(3):319-321
Bis-ortho-methyl-bis-meta-bromo Tröger base (TB) 2 and bis-ortho-methyl TB 3 were prepared in enantiopure form. The absolute configuration for (5S,11S)-(−)-2 was determined by X-ray diffraction. The sign of the longest wavelength band in the electronic CD spectrum is negative for both (5S,11S)-(−)-2 and (5S,11S)-(−)-3, as well as for the parent para-methyl TB (5S,11S)-(+)-1, which is in agreement with TD DFT B3LYP/6-31G(d,p) calculations. 相似文献
86.
87.
88.
R. G. Kostyanovsky A. P. Pleshkova V. N. Voznesensky Yu. I. Elnatanov 《Journal of mass spectrometry : JMS》1976,11(3):237-257
Further investigations have given new data confirming differences in fragmentation under electrol impact of compounds of trivalent nitrogen and other group V elements. These data have been obtained by comparision of the fragmentation of the amines, phosphines, arsines, benzyl derivatives, geminal systems and acyl derivatives. Mass spectra of tetraethyl derivatives of the group IV elements and acetyl triethyl germane have also been taken and compared with the previous ones. 相似文献
89.
Trapp O Schurig V Kostyanovsky RG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(4):951-957
For the first time the nitrogen inversion barriers in 3,3-unsubstituted trans-diaziridines, such as 1,2-di-tert-butyldiaziridine (1) and 1,2-di-n-butyldiaziridine (2) were determined. Enantioselective stopped-flow multidimensional gas chromatography was used to investigate the enantiomerization barrier of 1 between 126.2 and 171.0 degrees C (DeltaG ++ gas (150.7 degrees C) = 135.8+/-0.2 kJ mol(-1), DeltaH++ gas = 116.1+/-2.5 kJ mol(-1), DeltaS ++ gas == -46+/-2 J K(-1) mol(-1)). The separation of the enantiomers has been achieved in presence of the chiral stationary phase (CSP) Chirasil-beta-Dex with a high separation factor (alpha = 1.44 at 80 degrees C). In a complementary approach, the enantiomerization barriers of 1,2-di-tert-butyldiaziridine (1), 1,2-di-n-butyldiaziridine (2), 1-n-butyl-3,3-dimethyldiaziridine (3), and 1,2,3,3-tetramethyldiaziridine (4) were determined for comparison by enantioselective dynamic chromatography (DGC) and computer simulation of the dynamic elution profiles. The enantiomerization barrier of 2 was shown to be the highest among the nonsterically hindered diaziridines studied so far, whereas 1 exhibited the highest value found for strained nitrogen-containing rings, that is, aziridines, diaziridines and oxaziridines. 相似文献
90.
R. G. Kostyanovsky V. I. Markov I. M. Gella Kh. Khafizov V. G. Plekhanov 《Journal of mass spectrometry : JMS》1972,6(6):661-673
The mass spectra of azetidine, 2-methylazetidine, 2-phenylazetidine, methylene-bis-azetidines, their N-halo- and N-tosyl derivatives, 2-phenylazetine as well as N,N-dimethylmethane sulphonamide, N,N-dimethyl and N,N-diethyl- p-toluene sulphonamides have been investigated. The fragmentation of azetidine derivatives via the open form of the molecular ion is discussed. 相似文献