Voltamperometry of 1,4-dihydropyridine derivatives

Thirty-nine -substituted 1,4-dihydropyridine derivatives were subjected to electrochemical oxidation on a rotating platinum microelectrode in acetonitrile, and the E_p (E_1/2) values were measured. A satisfactory linear correlation between the E_p and Taft. ^* constants of the substituents in the position was observed. A linear correlation of the E_p values with the ⁰, - and ^– constants also exists.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1525–1529, November. 1975.     

Electronic structure and properties of heteropoly anions with the formula [PM12O40]n− [M=V(V), Mo(VI), W(VI)]

Institute of Catalysis, Academy of Sciences of the USSR. Central Institute of Physical Chemistry, Academy of Sciences of the German Democratic Republic. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 1, pp. 29–33, January–February, 1989.     

Synthesis of halogen substituted imidazo[4,5-e][1,4]diazepine-5,8-diones. Cyclic homologs of methylxanthines

Possible routes for synthesis of 2-haloimidazo[4,5-e][1,4]diazepines are discussed. Conditions for chlorination differ for homologs of caffeine, theophylline, and theobromine. For the caffeine homolog, both the 2-chloroand 2,6,6-trichloro products are obtained depending on the synthetic conditionsTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 955–958, July, 1992.     

A new steroid glycoside from the starfishPatiria pectinifera

From the glycoside fraction of the starfishPatiria pectinifera, after its desulfation, an artefactural glycoside has been obtained: 29(-L-arabinofuranosyloxy)-5-stigmastane-3,6,8,15,16-pentaol (I). The structure of (I) was shown by¹H and¹³C NMR spectra and mass spectra and by acetylation and high-temperature hydrogenation.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Institute of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 356–361, May–June, 1985.     

Synthesis of bacterial antigenic polysaccharides and their fragments V. Use of 1,2-o-isopropylidene-4,6-O-ethylidene-α-D-galactopyranose for the synthesis of oligosaccharides with 3-o-substituted galactopyranose residue

Conclusions Trisaccharide-D-glucopyranosyl-(14)--L-rhamnopyranosyl-(1 3)-D-galactose was synthesized by using, 2-O-isopropylidene-4,6-O-ethylidene--D-galactopyranose for producing 1 3-rhamnosylgalactose, linkage.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1609–1613, July, 1977.     

Synthesis and characterization of an Al(69)(3-) cluster with 51 naked Al atoms: analogies and differences to the previously characterized Al(77)(2-) cluster

A disproportionation process of a metastable AlCl solution with a simultaneous ligand exchange-Cl is substituted by N(SiMe(3))(2)-leads to a [Al(69)[N(SiMe(3))(2)](18)](3-) cluster compound that can be regarded as an intermediate on the way to bulk metal formation. The cluster was characterized by an X-ray crystal structural analysis. Regarding its structure and the packing within the crystal, this metalloid cluster with 4 times more Al atoms than ligands is compared to the [Al(77)N(SiMe(3))(2)](20)](2-) cluster that has been published four years ago. Although there is a similar packing density of the Al atoms in both clusters as well as in Al metal, the X-ray structural analysis shows significant differences in topology and distance proportions. The differences between these-at a first glance almost identical-Al clusters demonstrate that results of physical measuring, e.g., of nanostructured surfaces which carry supposedly identical cluster species, have to be interpreted with great caution.     

Synthesis and oxidation of 2,6-dimethyl-3, 5-di(phenoxycarbonyl)-1,4-dihydropyridines

A number of new aryl esters of acetoacetic acid were obtained in the reaction of phenols with diketene in the presence of triethylamine. Reaction of the esters thus obtained with hexamethylenetetramine gave, for the first time, aryl esters of 1,4-dihydropyridine-3,5-dicarboxylic acid, the oxidation of which with chloranil gave the corresponding pyridines.     

Correlation effects and interaction energy of π-electron shells in cumulene and acetylene molecules

By means of Hartree—Fock energy variance calculations it has been shown that the specific electroncorrelation energy in extended cumulene molecules is approximately 0.3 eV/electron and the specific energy of interaction between -electron shells is 0.1 eV/electron.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 6, pp. 514–517, November–December, 1993.