Triterpene glycosides of Acanthophyllum gypsophiloides IV. The structure of acanthophyllosides B and C

Summary Alternative structures for the acyloside chain of acanthophylloside B and C have been established.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 728–734, November–December, 1975.     

Carbon-bound diazeniumdiolates from the reaction of nitric oxide with amidines

[reaction: see text] The enediamine tautomer of a variety of substituted amidine free bases reacts with nitric oxide (NO) to produce compounds containing a carbon-bound diazeniumdiolate [R1R2R3C-N(O)=NO-] functional group (previously called "nitrosohydroxylamines"). The new reaction has been shown to be quite general, although the nature of the products does vary. Amidines containing more than one replaceable hydrogen produce polydiazeniumdiolates as intermolecular salts, while those in which only one diazeniumdiolation can occur provide zwitterionic salts. These diazeniumdiolated amidines are shown to be useful NO donor compounds which undergo very slow spontaneous dissociation on dissolution in pH 7.4 phosphate buffer to produce mixtures of NO and nitrous oxide containing mostly NO. The most advantageous manifestation of the new discovery is the preparation of the monodiazeniumdiolated amidine zwitterions. Reaction of the medically relevant alpha-adrenergic agonists tetrahydrozoline and idazoxan produced monodiazeniumdiolated amidine zwitterions from which NO release was observed for up to 28 days and showed little sign of ending. The reaction should be applicable to a variety of pharmaceutical agents, including NO synthase inhibitors, antitumor agents, and antibacterials.     

Pathways of Intramolecular Cyclization of Phosphorylated Ureas and Thioureas: A Theoretical Study

The stability of phosphorylated ureas and thioureas containing various substituents at the P and N atoms and the stability of their cyclization products, the corresponding diazaphospholidines and/or oxaza(thiaza)phospholines, was evaluated by PM3, MNDO, and DFT calculations. The thermal effects of cyclizations involving phosphorylated ureas (or thioureas) and of separate steps of their synthesis were calculated. According to the calculations, diazaphospholidine structures are preferably formed from substituted ureas and thiazaphospholine structures, from their thio analogs; formation of five-membered heterorings with the P-N bond is thermodynamically preferable as compared to their six-membered analogs.     

Synthesis of 4-alkyl-substituted 1,2,3,4-tetrahydropyrimidin-2-ones by the Biginelli reaction

p-Toluenesulfinic acid is an effective catalyst for condensation of acetoacetic ester with urea and aliphatic or aromatic aldehydes, leading to formation of 4-substituted 6-methyl-5-ethoxycarbonyl-1,2,3,4-tetrahydropyrimidin-2-ones.M. V. Lomonosov State Academy of Fine Chemical Technology, Moscow 117571, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 979–982, July, 1998.     

Effect of the nature of the metal oxide on selective transformation of methane under unsteady conditions in the absence of oxidant in the gaseous phase

The catalytic transformation of methane into higher hydrocarbons was studied under unsteady conditions on oxides of various metals (Pb, Fe, Nb, Ti, Cd, Mo, Mg, Zn, Zr, Bi, Mn), and also on Sr-, La-, Y-, and Mn-containing oxides of perovskite structure. It is shown that the effectiveness of the catalysts not only depends on their chemical composition, but also is determined to a considerable degree by the specific surface of the oxides. L. V. Pisarzhevskii Institute of Physical Chemistry, Academy of Sciences of Ukraine, 252039 Kiev, Prosp. Nauki, 31, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 2, pp. 91–95, March–April, 1997.     

Acid-base properties of indolylglyoxal and some acetylindoles

A spectrophotometric study of the acid-base properties of 3-acylindoles showed that they were stronger acids than the alkylindoles. It was found that protonation of these compounds occurs at the carbonyl group. For indolylglyoxal, 3-acetylindole, and 1-methyl-3-acetylindole the pK_b was determined; the pK_afor indolylglyoxal and 3-acetylindole was measured in 50% aqueous methanol.Translated from Khimiya Geterotsiklicheskhikh Soedinenii, No. 12, pp. 1621–1624, December, 1987.     

X-ray studies of supported copper-aluminium catalysts

Structural peculiarities of the formation of copper-aluminium catalysts at copper concentrations <10 wt% and calcination temperatures of 573–1173 K have been studied.

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<10% . 573–1173°K.

     

Molar volumes and ion pairing of lithium halides in alcohols

The concentration dependence of the apparent molar volumes of lithium halides (and electrolytes in general) in alcohols (and solvents permitting association in general) is, in the first instance, due to changes in the degree of association and to the inherent difference between the apparent molar volumes of the ions and of the ion pairs. Previous publications on the molar volumes of electrolytes in organic solvents, disregarding altogether ion pairing, appear to be incorrect. Data from the literature for lithium chloride and lithium bromide in normal primary alcohols and several branched alcohols from C₁ to C₈ and data from our laboratory for lithium halides in 1-hexanol and 2-ethyl-1-hexanol served for the determination of φ _V and φ _E . Electrical and structural contributions to the values of these functions for the ions and for the ion pairs are discussed.     

Wave mechanics - the first fifty years : edited by W.C. Price,S.S. Chissick and T. Ravensdale,Butterworths, London, 1973, pp. 435, price £12.00

The free NH₃ molecule and the [Zn(NH₃)₄]²⁺ ion were studied by the kinematic coupling approach. The pure effects of this coupling were found to be small, and some modifications had to be introduced in order to get a reasonable force field. The force constants deduced for the skeletal vibrations are comparable with those of a quasi-exact force field. Calculated frequencies for [⁶⁸Zn(NH₃)₄]²⁺ and [⁶⁴Zn(ND₃)₄]²⁺ are reported in addition to those of [⁶⁴Zn(NH₃)₄]²⁺. Mean amplitudes of vibration for [⁶⁴Zn(NH₃)₄]²⁺ are given.     

Chloride, -Hydride and -Borohydride Derivatives of Difluorenyl Thallium(III)

Chloride¹), borohydrides²) and hydrides³) of dicyclopentadienyl thallium (III) and diindenyl thallium (III) have already been reported. The present communication deals with a study on the preparation and characterization of difluorenyl thallium (III) chloride, -hydride and -borohydride.