Synthesis and spectral properties of 2-methyl-5-aryl-1,3,4-oxadiazoles

By heterocyclization of 1-acyl-2-aroylhydrazines under the influence of strong dehydrating substances, a series of 2-methyl-5-aryl-1,3,4-oxadiazoles has been synthesized and their UV, IR, and PMR spectra have been investigated. Through analysis of data on the influence of substituents on the position of the maximum in the electronic absorption spectrum, together with calculated data, it has been shown that the long-wave band of 2-methyl-5-phenyl-1,3,4-oxadiazole is due to an S₀–S₁ transition of the –^* type and that it is a charge transfer band for transfer from the phenyl radical to the oxadiazole ring; the 1,3,4-oxadiazole ring as a substituent has an electron-acceptor character.Institute of Single Crystals, National Academy of Sciences of the Ukraine, Khar'kov 310001. Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–821, June, 1997.     

Immobilization of Urease and Cholinesterase on the Surface of Semiconductor Transducer for the Development of Light-Addressable Potentiometric Sensors

Various methods for the immobilization of urease and butyrylcholinesterase on the insulator surface of a laser-scanned semiconductor transducer (LSST) have been tested and compared for the development of an enzyme-based light-addressable potentiometric sensor (LAPS). The method of preparing photocurable membranes on LAPS is presented, and a new type of enzyme LAPS with photocurable polymeric enzyme membranes has been elaborated. It was found that sensors prepared by means of covalent bonding and cross-linking with inactive protein (type SIII) and with photocurable membrane matrices (type SIV) are more prospective. The enzyme LAPSensors with photocurable membranes demonstrate a degree of sensitivity close to the theoretical value and working ranges of 6.3·10^–5–1.1·10^–2 and 1·10^–4–1·10^–1molL^–1 urea for acrylamide and acrylate-based membrane matrices, respectively, and 2.5·10^–4–2·10^–1molL^–1 butyrylcholine for an acrylamide membrane matrix. It is shown that such sensors can be also used for the analysis of enzyme inhibitors.     

MFTIR spectra of polyethylene synthesized on germanium surfaces

MFTIR spectra of thin layers of polyethylene synthesized on the surfaces of germanium monocrystals in the 700–3000 cm^–1 range have been investigated. The optical constants of the polymer n() and () have been calculated in the range of natural absorption corresponding to the C-H valence vibration bands. Dichroism of the 2848 and 2912 cm^–1 bands disclosed is caused by the orienting influence of the monocrystal surface and in value is comparable with values obtained for monoaxially oriented massive specimens of polyethylene having a high degree of crystallinity. There have been established reversible changes of the relative orientation function of the macromolecule surface layer during heating and cooling of the specimens in the temperature range 293–355 K. This is explained by the nematic state of the polymer in the thin layer, the macromolecules of which are chemically bonded to the surface of the germanium monocrystal.Deceased.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 380–383, May–June, 1988.The authors express their gratitude to K. K. Kalnin'sh for valuable discussion of material in the article and to M. E. Yudovich for his assistance in the calculations.     

Anabasine and cytisine derivatives as reversible cholinesterase inhibitors

A number of analogs of acetyl--methylcholine, containing residues of the alkaloids anabasine and cytisine as cyclic ammonium groupings, have been synthesized. The structures of the substances obtained have been confirmed by their IR and PMR spectra and the result of elementary analysis. The kientic parameters of the interaction of the compounds synthesized with acetylcholinesterase (ACE) of human blood erythrocytes and with butylcholinesterase (BuCE) of horse blood serum have been investigated. All the substances synthesized proved to be reversible inhibitors of ACE and BuCE.Institute of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 97–100, January–February, 1988.     

Alkaloids ofNitraria schoberi. Structure of nitraraine

The dehydration of nitraraine leads to the formation of 1-(2,6-dimethylbenzyl)--carboline, together with other products. Several isomeric 1-(dimethylbenzyl)--carbolines have been synthesized for comparison. The products of acylation, hydrogenation, and oxidation of the alkaloid nitraraine have been studied. The results obtained have shown its structure as (±)-16-hydroxymethylyohimb-16-ene.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii. No. 4, pp. 536–544, July–August, 1985.     

Glycosylation of triterpenoids of the dammarane series. VII. Dammar-24-ene-3α,12β,17α,20(S)-tetraol β-D-glucopyranosides

Glucosides have been synthesized from dammar-24-ene-3,12,17,20(S)-tetraol (betulafolienetetraol), isolated from the leaves ofBetula pendula. Condensation with -acetobromoglucose in the presence of silver oxide and silicate has given acetylated betulafolienetetraol 3- and 12- mono- and 3,12- and 3,20-di-O--D-glucopyranosides, the total yield of which amounted to 75–80%. The structures of the semisynthetic glycosides have been established on the basis of the results of IR,¹H and¹³C NMR spectroscopy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 225–229, March–April, 1988.     

Synthesis, structure, and anticholinesterase activity of some organophosphorus derivatives of anabasine

Anabasine derivatives based on methylphosphonothoic acid have been synthesized. It has been shown by PMR spectroscopy that in solution O-alkyl O-[-(anabasin-1-yl)ethyl] methylphosphonothioates exist in two stereomeric forms, which is due to the influence of the optically active anabasine residue. It has been shown that these compounds are competitive reversible inhibitors of acetylcholinesterase and of butyrylcholinesterase.Institute of Bioorganic Chemistry of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 561–565, July–August, 1987.     

Synthesis of derivatives of the androstane series

Summary Hydrazones and symmetrical dihydrazones of 2-methyltestosterone and its 17-methyl and 17-ethyl derivatives have been synthesized.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 5, pp. 354–359, 1966     

Crystal and molecular structure of the sesquiterpene ketone 9α-hydroxymurola-4-one

Summary The crystal and molecular structure of a ketone (9-hydroxymurola-4-one) synthesized from -cadinol has been investigated. Under the conditions of its production and isolation, the ketone retains the configurations of the asymmetric centers.Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 158–161, March–April, 1979.     

Synthesis and spatial structure of methyl substituted 2-phenylpiperidine-4-spiro-5′-imidazolidine-2′,4′-diones

Piperidine-4-spiro-5-irnidazolidine-2, 4-diones have been synthesized from the appropriate methyl substituted 2 phenyl-4-hydroxypiperidines and 4-cyano-4-aminopiperidines by the Bucherer—Bergs and Strecker methods. The stereocheinical composition and spatial structure of the compounds synthesized have been established from¹H and¹³C NMR data.Moscow State Academy of Fine Chemical Technology, Moscow 117571. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 798–801, June, 1994. Original article submitted May 11, 1994.     

Synthesis of triterpene glycosides

Summary 1. The acyl--D-glucopyranosides, acyl--D-xylopyranosides, and acyl--L-arabinopyranosides of oleanolic and ursolic acids have been synthesized for the first time.2. A method for the synthesis of acyl glycosides of triterpene hydroxyacids with hindered carboxy groups has been developed.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 6, pp. 405–410, 1966     

Elements in car and truck tires and their volatilization upon incineration

The trace metal loading of used car and truck tires and the fractions of the metals volatilized upon incineration of the tire were determined. INAA was chosen due to its multielement analysis capability and its low detection limit for many elements. A high purity planar germanium detector was used. Among the elements measured were, Al (4–150 g/g), Ti (41–730 g/g), V (0.04–0.4g/g), Mg (>80–580 g/g), Zn (1–2.2%) as typical concentrations; also some amounts of antimony, bromine and arsenic have been found. Major differences in elemental concentrations have been observed between the tread and the wall of a tire, and also between different brands.     

Dialkylamino- and alkoxytrialkylstannanes as reagents for synthesis of organoboryl (trialkylsilyl) ketenes

Dialkylamino- and alkoxytrialkylstannanes have been studied as N- and O-nucleophilic reagents in substitution reactions at the B-Br bond. The previously unknown bis(dialkylamino)- and dialkoxyboryl trialkylsilyl ketenes were synthesized. Some peculiarities of the reactivity of these compounds have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 911–915, May, 1994.This research was carried out in the framework of the Universities of Russia State Program.     

The O-nitration of tertiary unsaturated alcohols andα-epoxyalcohols

Conclusions The method for O-nitrating unsaturated alcohols and-epoxyalcohols has been extended to tertiary alcohols;, -dimethylallyl and, ;-dimethylglycidyl nitrates have been synthesized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1354–1355, June, 1967.     

Theoretical approach to the problem of finding effective luminophors in the isocarbostyril series

It has been established that the main reason for the low fluorescence quantum yield of unsubstituted isocarbostyril (I) is the thermally activated intersystem crossing S T_n. The positions in the molecule at which the introduction of substituents should cause the greatest bathochromic displacement of the absorption spectra have been determined on the basis of data from quantum-chemical calculations. Lowering of the S₁ level results in a decrease in the probability of intersystem crossing and, as a consequence, in an increase in the quantum yield. A number of derivatives of I have been synthesized, and their luminescence-spectroscopic properties have been investigated. The causes of the instability of 4-hydroxy- and 4-NH₂-isocarbostyrils have been discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 4, pp. 474–479, July–August, 1988.     

Synthesis and some properties of 4-oxo-3,4-dihydro- and 2,4-dioxo-1,2,3,4-tetrahydropyrimido[5,4-b]indoles

The condensation of N-(2-ethoxycarbonylindol-3-yl)-N,N-dialkylamidines with ammonia, primary amines, and hydrazines has given a series of 4-oxopyrimido[5,4-b] indoles which have been converted into the 4-chloro and then into the 4-methoxy, 4-dialkylamino, and 4-mercapto derivatives. 2,4-Dioxopyrimido[5,4-b]indoles have been synthesized by the successive action of chloroformic ester and then methylamine, hydrazine, or ethylhydrazine on 3-amino-2-ethoxycarbonylindoles differing by their substituents in position 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 635–639, May, 1985.     

The synthesis and study of the reactivity of p-[di-(2-chloropropyl) amino] phenylalkanoic acids

Summary p-[Di-(2-chloropropyl)amino]benzoic, p-[di-(2-chloropropyl)-amino]cinnamic, p-[di-(2-chloropropyl) amino]--phenylpropionic acids and a series of their derivatives have been synthesized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 643–646, March, 1969.     

A New Understanding of the Relationship Between Solubility and Particle Size

Most discussions of the relationships between crystal solubility and particle size have hitherto been concerned with vapor condensation and have led to the prediction that the vapor pressure increases with curvature. Here, thermodynamic arguments are presented to show that such relationships, describing crystal solubility as a function of particle size, originally put forward by Ostwald and later corrected by Freundlich, may be unjustified for determining interfacial tension at solid–liquid interfaces. The Kelvin or Gibbs–Thomson equations are valid for liquid–vapor systems, but not for solid–liquid interfaces. Recent experimental observations have demonstrated that interfacial tension data obtained by the solubility–size approach are unreasonable. This leads to the conclusion that Ostwald ripening may not be due to a higher solubility of smaller crystals, but rather to a net negative interfacial tension between solid and solution.     

Organoboron compounds. 374. Cyclic compounds of the chelate type from 2-pyridyl-and 2-pyrimidinylaminoboranes and dicyclohexylcarbodiimide

Conclusions New chelate compounds of boron, in which the chelating agents are, respectively, N.N-dicyclohexyl-N'-(2-pyridyl)guanidine and N,N-dicyclohexyl-N'-(2-pyrimidinyl)guanidine, have been synthesized by adding 2-pyridylaminodiorganylboranes and 2-pyrimidinylaminodiorganylboranes to dicyclohexylcarbodiimide.For the preceding report see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 659–663, March, 1980.     

Interaction with cholinesterases and conformational analysis of analogs of acetylcholine containing the alkaloids ephedrine and pseudoephedrine

Acetyl--methylcholine analogs of ephedrine and pseudoephedrine have been synthesized. The kinetics of their interaction with cholinesterases have been studied. To explain the differences in the sensitivity of the enzymes to conformers, a conformational analysis of the compounds synthesized has been made by the NMR method.A. S. Sadykov Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 654–658, September–October, 1988.