Secondary-ion mass spectra of pennogenin glycosides

LSIMS mass spectra of pennogenin glycosides have been studied; the most characteristic ions are (M+H–H₂O)⁺ (with glycerol as the liquid matrix) and (M+Na)⁺ (with glycerol +NaCl as matrix). In both cases the peaks of ions formed as the result of the successive elimination of the carbohydrate units, the breakdown of the bonds of the terminal pyranoses, the cleavage of the bonds of the rings D and E, and the peaks of the ions Agl⁺ and (Agl–H₂O)⁺ were observed.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. All-Union Scientific-Research Institute for Agricultural Biotechnology, All-Union Academy of Agricultural Sciences, Moscow. Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 523–525, July–August, 1991.     

2H-imidazole-N-oxides as spin traps

The capacity of 2H-imidazole-1-oxides, which contain an aldonitrone group, for spin capture was investigated. The parameters of spin adducts with^.OH,^.CH₃, and^.CH₂OH radicals are reported.Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences. Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1064–1068, May, 1992.     

Structural and dynamic investigations of aqueous clusters of Na+ and K+

Using computer modeling, we have studied Na⁺–24H₂O and K⁺–24H₂O clusters. We propose ion-water interaction potentials. We obtain structural, energy, and dynamic characteristics of the studied clusters. We show different mechanisms for exchange of water molecules surrounding the Na⁺ and K⁺ ions: single-particle in the case of Na⁺, and close to K⁺, along with single-particle exchange, a large percentage of multiparticle cooperative exchange of water molecules. This difference is explained by the different degrees of orientation of the water molecules surrounding these ions, by the presence of a unified deformed network of H bonds in the K⁺ cluster and its absence in the Na⁺ cluster. We propose a negative hydration mechanism for the K⁺ ion.Institute of General and Inorganic Chemistry, Russian Academy of Sciences. Institute of Physical Chemistry, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 96–104, March–April, 1993.     

Coumarins of Fraxinus mandschurica and F. potamophila

Summary The leaves ofFraxinus mandschurica Rupr. and the bark ofF. potamophila Herd. have yielded esculetin, fraxinol, and a new coumarin C₁₀H₈O₅, mp 228–230°C which we have called isofraxetin. On the basis of NMR and UV spectroscopy it has been established that isofraxetin is 5,7-dihydroxy-7-methoxycoumarin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Institute of Chemistry, Academy of Sciences of the Turkmen SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 493–497, July–August, 1973.     

Features of the mass spectra of C18-diterpene alkaloids

Fragmentation under electron impact of eleven C₁₈-diterpene alkaloids with an oxygen function at C-4 has been investigated. The contributions of various modes of forming the (M - CH₃)⁺ ions have been determined. The mechanism of the appearance of the fragments (M - CH₃)⁺ and (M - OCH₃)⁺ at the expense of the methoxy groups at C-14 and C-16 has been considered. The characteristic nature of the parameters of the metastable peaks in the transitions to these daughter ions has been shown. Minor directions of the fragmentation of 3,4-epoxy- and 4-hydroxy bases have been characterized.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 95–106, January–February, 1989.     

Laser activation of ethylene and formaldehyde quenching

A novel method is described for oxidizing ethylene with molecular oxygen to give formaldehyde under normal conditions in the presence of the beam from a continuous wave low-power CO₂ laser (943 cm^–1), which is in resonance with the ethylene vibrational mode p(CH₂) = 949 cm^–1; the method involves activating the CH₂-CH₂ bonds to failure with the formation of biradicals and then quenching the formaldehyde, which is out of equilibrium as regards temperature.Institute for General and Inorganic Chemistry, Academy of Sciences of The Ukrainian SSR, Kiev. Translated from Teoreticheskaya i Eksperimental'naya Khimiya, No. 2, pp. 220–223, March–April, 1991. Original article submitted April 19, 1990.     

Electronic structure and vibrational spectrum of acetylthiocarbamide

An approximate quantum chemical optimization of the geometric parameters of the acetylthiocarbamide molecule CH₃CONHCSNH₂ was carried out using the MNDO/H approximation. Bond lengths, bond angles, enthalpy of formation, total energy, ionization potential, and dipole moment were estimated, and the effective charges on the atoms and the bond orders were calculated. An analysis of the normal vibrations of the acetylthiocarbamide molecule and its deuteroanalog CH₃CONDCSND₂ was carried out. The force fields have been estimated. The frequencies, potential energy distribution among the vibrational coordinates, and the frequencies for the partially and completely deuterated acetylthiocarbamide molecules have been calculated.A. A. Baikov Institute of Metallurgy, Russian Academy of Sciences. A. A. Sechenov Moscow Academy of Medicine. N. S. Kurnakov Institute of General and Inorganic Chemistry. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 58–65, March–April, 1993.     

Fragmentation of some 1,2-epoxyguaianolides

The mass spectra of four guaianolides with epoxy groups of C₁–C₂ have been studied. A mechanism is proposed for the formation of the main ions. The origin of the secondary fragments has been confirmed by measurements of elementary compositions.Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 796–800, November–December, 1980.     

New glycosides from the holothurian Cucumaria japonica

Four new compounds have been isolated from the fraction of weakly polar triterpene glycosides of the holothurianCucumaria japonica: cucumariosides A₁-2 (I), A₀-1 (II), A₀-2 (III), and A₀-3 (IV). The structures of these substances have been established by chemical and physical methods.Deceased.Pacific Ocean Institute of Bioorganic Chemistry, Far-Eastern Scientific Center, Russian Academy of Sciences, Vladivostok. Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 242–248, March–April, 1993.     

Mass spectrometry of pennogenin glycosides

The electron-impact mass spectra of five unesterified pennogenin glycosides, which contain the M⁺ or (M - H₂O)⁺ peaks, have been obtained. The characteristic features of the fragmentation of these compounds have been studied. In addition to ions characterizing the successive elimination of carbohydrate units, fragments have been detected which show the breakdown of the terminal pyranose ring. Five new directions of the fragmentation of the spirostanol skeleton due to the presence of an OH group at C-17 have been found.Institute of the Chemistry of Plant Substance, Academy of Sciences of the Uzbek SSR, Tashkent. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Science Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 337–341, May–June, 1986.     

Trisulfated glycosides from the holothurianCucumaria japonica

Three new triterpene glycosides have been isolated from an alcoholic extract of the Pacific Ocean commercial holothurian Cucumaria japonica: cucumariosides A _T 1 (I), A _T 2 (II), and A _T 3 (III). The structures of these glycosides have been established by chemical and physical methods.Deceased.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbekistan Republic, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 369–374, May–June, 1993.     

Vibrational spectra and conformations of chloromethyldimethyl- and tris(chloromethyl)phosphine oxides

A study was carried out on the IR spectra of (CH₃)₂P(O)CH₂Cl and (CH₂Cl)₂PO. The frequencies and forms of the normal modes were calculated. The molecular mechanics method was used to calculate the energy of the various conformations of these molecules. (CH₃)₂P(O)CH₂Cl in the liquid and solution is a mixture of trans and gauche conformations, while (CH₂Cl)₃PO is a mixture of trans,gauche,gauche, trans,gauche,gauche, and gauche,gauche,gauche conformations.S. M. Kirov Kazan Chemical Engineering Institute and A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 6, pp. 38–46, November–December, 1989.     

Reaction of diazoalkanes with unsaturated compounds. 11. Relative reactivity of olefins on catalytic cyclopropanation with diazomethane and palladium catalysts

The relative reactivity of unsaturated compounds on catalytic cyclopropanation with diazomethane in the presence of catalysts based on Pd²⁺ [Pd(OAc)₂, Pd(acac)₂, (PPh₃)₂·PdCl₂] has been studied using competing reactions. An interconnection was shown between the relative reactivity of the olefins and the coordinating activity of the C=C bond depending on its strain and spatial environment.For previous communication, see [1].Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, 450054 Ufa; N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2353–2361, October, 1992.     

Electrochemical and chemical oxidation of alcohols in a two-phase system using N-oxopiperidinium salt: Synthesis of 4-chlorobutanal,formylcyclopropanes, andm-phenoxybenzaldehyde

Oxidation of 4-chlorobutanol-1, cyclopropylcarbinols, andm-phenoxybenzyl alcohol with electrogenerated bromine, molecular bromine, and sodium hypochlorite using N-oxopiperidinium salt in the two-phase system CH ₂ Cl ₂ —water gave the corresponding carbonyl compounds with good yields.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 941–946, April, 1992.     

Synthesis and carbene decomposition of functionally substituted diazoacetic acid esters. 8. Cyanomethyl diazoacetate

Diazoacetic acid cyanomethyl ester (1) was synthesized, and its chemical conversions were investigated. Catalytic denitration of compound 1 with Rh₂-(OAc)₄ in CH₂Cl₂ at 25°C in the presence of alkenes, dienes-1,3, and alkynes-1 afforded the corresponding cyclopropane- and cyclopropenecarboxylic-3 acid esters in yields of 80–85% and was almost independent of the type of unsaturated acceptor. Competitive interaction methods showed that compound 1 has a high reactivity toward terminal alkenes and alkynes, which is comparable to that of methyl and propargyl diazoacetates.For previous communication, see [1].N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 357–362, February, 1992.     

Synthesis of regular polypeptides including lysine, proline, and alanine residues

Conclusions Polypeptides of the following sequences have been obtained: -Lys-Pro-,-Lys₂-Pro-, -Lys₃-Pro-,-Lys-Pro₂-, and -Lys-Ala-, with molecular weights of from 1000 to 14,000. It has been established that the use of pentachlorophenyl esters for polymerization in place of 2,4,5-trichlorophenyl esters leads to a considerable increase in the molecular weights of the polypeptides.Institute of Chemistry, Academy of Sciences of Tadzhik SSR. Institute of Molecular Biology, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 210–213, March–April, 1974.     

Secondary-ion mass spectrometry of lycotetraosides of the spirostan and furostan series

The secondary-ion mass spectra of seven steroid lycotetraosides have been obtained by the SIMS method. On the use of a glycerol matrix, all the compounds of the spirostan series, including those with an additional carbohydrate substituent a C-24, formed the (M+H)⁺ ions, while a lycotetraoside of the furostan series formed the (M–H₂O+H)⁺ ion. They subsequently decomposed by the alternative successive elimination of the terminal carbohydrate units of the lycotetraose. Substituents at C-25 and C-26 were ejected in the form of glucose molecules. Fragments of the aglycon and of the lycotetraoside moieties of the molecules were recorded. When NaCl was added to the same matrix, all the compounds gave preferentially the (M+Na)⁺ and (M+2Na–H)⁺ ions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. All-Union Scientific-Research Institute of Agricultural Biotechnology, Lenin All-Union Academy of Agricultural Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 53–58, January–February, 1991.     

Synthesis of polypeptides with the sequences-Gly-Gly-Ala-, -Gly-Gly-Lys(Tos)-, and-Gly-Gly-Glu(OCH3)- and the influence of triethylamine on the degree of their polycondensation

Conclusions The synthesis of polytripeptides with the sequences -Gly-Gly-Ala-,-Gly-Gly-Lys(Tos)-, and -Gly-Gly-Glu(OCH₃)-having molecular weights of 11,000, 39,000, and 3000, respectively, have been effected.Institute of Molecular Biology, Academy of Sciences of the USSR. Institute of Chemistry, Academy of Sciences of the TadzhSSR, V. I. Lenin Tadzhik State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 206–210, March–April, 1974.     

Spatial structures of the sesquiterpene germacrane lactones tanachin and tamirin

An x-ray investigation has been made of the sesquiterpene lactones tanachin and tamarin: diffractometer, CuK-radiation, 845 and 981 reflections, respectively, direct method, R factors 0.064 and 0.065. The conformations of both molecules are boat-boat with configurations of the¹D₁₄ and¹⁵D₅ types.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodynkh Soedinenii, No. 2, pp. 198–204, March–April, 1989.