Synthesis and structure of amino esters of menthol

The conditions for the acylation of (–)-menthol with monochloroacetyl chloride have been studied. Amino esters of (–)-menthol have been obtained by the nucleophilic replacement of the chlorine in (–)-menthol monochloroacetate by residues of secondary amines. Their properties and their mass, IR, and¹³C NMR spectra are described.Institute of Physical Organic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 728–733, November–December, 1981.     

Synthetic analogs of natural flavolignans VII. Synthesis of 1,3-benzodioxane analogs of dehydrosilybin

Structural analogs of dehydrosilbyn have been obtained from 1,3-benzodioxane derivatives of chalcones. Their structures have been confirmed by their PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 623–625, September–October, 1994.     

Nonempirical calculations of potential-energy surfaces for nucleophilic addition of H− and F− to an acetylene molecule

The minimal energy paths for the nucleophilic addition of a hydride ion (H^–) and a fluoride ion (F^–) to a molecule of acetylene (A) have been calculated with the use of 3–21++G and 3–21+G double basis sets in the framework of the Hartree-Fock-Roothaan method. The values of the total energies of the reactants, transition states, and products have been refined by means of calculations with more complete basis sets [6–31++G// 3–21++G and 6–31++G*//3–21++G for reaction (1); 6–31+G*//3–21+G and 6–31++G**//3–21+G for reaction (2)] and by taking into account the correlation energy for reaction (1) in the framework of the SCEP/6–31++*//3–21++G method. It has been established that the activation energy of reaction (2) is 15.94 kJ/mole lower than that for reaction (1), that reaction (1) is exothermic, and that the enthalpy change accompanying reaction (2) is close to zero. The character of the distribution of the electron density along the minimal energy paths of both reactions has been analyzed, and the differences appearing as a result of the replacement of the soft nucleophile H^– by the harder nucleophile F^– have been ascertained. The results of the calculations have been compared with the results available in the literature for reaction (1).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 149–155, March–April, 1989.     

Synthetic and modified isoflavonoids XVIII. Synthesis of 7-isopropoxy-substituted analogs of pseudobaptigenin

7-Isopropoxy derivatives of isoflavones have been synthesized from 1,3-benzodioxole, 1,4-benzodioxane, and 1,4-benzodioxepane analogs of pseudobaptigenin. Their structures have been confirmed by PMR.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 365–369, May–June, 1997.     

Distribution studies of metal ions on stannic arsenate in butanol-HNO3 systems: Quantitative separation of Ni−Fe,Ni−Cu,Cd−Hg and Pb−Hg

Summary This paper deals with systematic distribution studies of metal ions on stannic arsenate in butanol-HNO₃ systems. K_d values of metal ions have been determined by the batch process in solvent systems containing varying proportions of butanol and 50% HNO₃. Quantitative binary separations of Ni–Fe, Ni–Cu, Cd–Hg and Pb–Hg have been obtained on the basis of information from the studies.     

Spectroscopic characterization of environmentally relevant C10-chloroterpenes from a photochemically modified toxaphene standard

Twenty-five pure environmentally relevant toxaphene components have been isolated from photochemically modified technical toxaphene by means of a combination of column chromatography on silica gel and preparative high resolution liquid chromatography. These compounds are 6 chlorinated camphenes (1–3, 5, 7, and 11) and 19 chlorinated bornanes (4, 6, 8–10, 12–16, 18–24, 26, and 27 according to Table 1). Two further chlorobornanes (17 and 25) have been isolated from a highly chlorinated mixture obtained by the excess chlorination of 2-exo,10-dichlorobornane. The structural elucidation of the isolated compounds has been carried out with spectroscopical methods.     

Synthetic and modified isoflavonoids. VII. Synthesis of benzodioxocane analogs of pseudobaptigenin

Benzodioxocane analogs of pseudobaptigenin have been synthesized, and their structures have been shown by chemical transformations and PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 223–226, March–April, 1994.     

Synthesis of aryl fluorides by decomposition of aryldiazonium hexafluorogermanates

Conclusions Seven aryldiazonium hexafluorogermanates have been synthesized, and the corresponding aryl fluorides have been prepared from them in 60–75% yield, by thermal decomposition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2750–2752, December, 1967.     

Chemical synthesis and enzymatic assembly of fragments of the DNA coding immunodominant epitopes of human immunodeficiency virus

More than twenty 13- to 55-membered oligo(poly)nucleotides have been synthesized by the H-phosphonate solid-phase method in the manual variant using an original procedure. From the oligonucleotides obtained, seven DNA duplexes coding immunodominant epitopes of HIV-1 proteins have been formed: 598–609 and 737–748 gp41, 91–115 and 105–115 gag, and 940–951 pol and a number of its mutants. The ligase assembly and polymerization of the DNA duplexes obtained has been carried out. The efficiency of ligation amounted to from 60 to 90%. The possibility of their directed polymerization was determined by the flanking of the duplexes by partially completed half-sites of restrictases BamHI and XhoI.Abbreviations adopted: HIV-1 — human immunodeficiency virus, type 1; (+)-chain — the coding chain — and (–)-chain the chain complementary to the coding chain of the DNA duplex; CPG — controlled-pore glass; PAAG — polyacrylamide gel; Py — pyridine.D. I. Ivanovskii Institute of Virology, USSR Academy of Medical Sciences, Moscow. V. A. Engel'gardt Institute of Molecular Biology, USSR Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 393–399, May–June, 1990.     

Stereochemistry of the products of the hydrogenation of leucomisin

4-H(4-Me)-3-hetarylcoumarins modified by 1,3-benzodioxolane and 1,4-benzodioxane residues have been synthesized. The structures of the compounds obtained have been confirmed by PMR.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 230–233, March–April, 1994.     

New sesquiterpene quinones from marine sponges of the order dictyoceratida

Isospongiaquinone and a new sesquiterpene quinone — dictyoceratidaquinone — have been isolated from a dictyoceratidan marine sponge. Ilimaquinone and the new aminoquinone, a sesquiterpenylamylaminohydroxyquinone, have been isolated from a spongeSpongia sp. Synthetic analogs of natural aminoquinones have been obtained by replacing the methoxy group in ilimaquinone and isospongiaquinone by an amine group.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 47–51, January–February, 1990.     

Synthetic and modified isoflavonoids XIX. Synthesis of 8-methyl-substituted analogs of pseudobaptigenin

New 8-methyl-substituted chromones with 1,4-benzodioxane and 1,5-benzodioxepane nuclei in position 3 have been synthesized. Their structures have been confirmed by chemical transformations and PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 370–374, May–June, 1997.     

Thermodynamic Properties of NaCl Solutions at Subzero Temperatures

Heat capacities at infinite dilution of NaCl (aq) for the temperature range 0 to –25°C and apparent molar volumes at infinite dilution for 0 to –15°C have been estimated from a synthesis of experimental data collected at subzero temperatures. The parameters of the Helgeson–Kirkham–Flowers (HKF) equation for Na⁺ (aq) have been obtained, from which the Gibbs energies of Na⁺ and Cl^– have been calculated. The estimated values of Pitzer-equation parameters for thermal and activity-coefficient properties have been adjusted for subzero temperatures. The experimental phase diagram for the NaCl–H₂O system could be reproduced with these data, demonstrating the low-temperature applicability of the HKF model to extrapolate thermodynamic properties of aqueous-solution species at infinite dilution.     

Apparent Molar Volumes of Sodium Methylbenzoates in N, N-Dimethyl Formamide–Water Mixtures at 298.15 K

Densities of sodium methylbenzoate (o-, m-, p-) have been measured in dimethyl formamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium methylbenzoates in DMF–H₂O mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H₂O mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.     

Synthetic analogs of natural flavolignans. V. A new synthesis of 6-halogeno-1,3-benzodioxane analogs of silandrin and hydnocarpin

6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra.KIEN Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Taras Shevchenko Kiev University, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 494–498, July–August, 1994.     

Synthetic analogs of natural flavolignans IX. Synthesis of 3-amino-substituted analogs of hydnocarpin

New 3-amino-substituted chromones with 1,3-benzodioxan and 1,4-benzodioxan nuclei in position 2 have been synthesized. The structures of the compounds obtained have been confirmed by their PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 178–181, March–April, 1999.     

Synthetic and modified isoflavonoids. XIII. Synthesis of analogues of fujikinin

Analogues of a natural isoflavone glycoside — fujikinin — have been synthesized. Their structures have been confirmed by their PMR spectra.Taras Shevenko Kiev University: KIEN, Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 347–351, May–June, 1994.     

Phytoecdysteroids of plants of the genusSilene XVI. 5α-sileneoside E FromSilene brahuica

Derivatives of derrusnin and also its benzodioxane and benzodioxepane analogs have been synthesized. The structures of the compounds obtained have been confirmed by spectral studies.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 226–230, March–April, 1994.     

Synthetic and modified isoflavonoids IV. Synthesis of benzodioxepane analogues of pseudobaptigenin

Benzodioxepane analogues of pseudobaptigenin have been synthesized and their structures have been established by chemical transformations, elementary analysis, and PMR spectroscopsy.Taras Shevchenko Kiev University KIEN. Karakalpak Branch, Uzbekistan Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 814–820, November–December, 1993.     

A study of the reaction of pentacyclic triterpenoids with concentrated sulfuric acid

Summary The conditions for the reaction of triterpenoids with concentrated sulfuric acid have been studied by the method of mathematical planning, and the optimum conditions for performing this reaction have been found.Pyatigorsk Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 294–296, May–June, 1971.