Analogs of purine nucleosides and purine mono- and polynucleotides

Phosphorylation of 6-substituted 9-(1, 5-dihydroxy-3-pentyl)purines with 2-cyanoethyl phosphate in the presence of dicyclohexylcarbodiimide in anhydrous pyridine gave their 1, 5-diphosphates. Oligomers containing pyrophosphate and ester bonds were obtained by polycondensation of 1, 5-diphosphates of 6-dimethylamino- and 6-oxo-9-(1, 5-dihydroxy-3-pentyl)purines with the appropriate 9-(1, 5-dihydroxy-3-pentyl) purines.See [1] for communication V.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 693–696, May, 1976.     

Acyclic analogs of nucleosides. Synthesis of 1,5-dihydroxy-3-oxa-2-pentyl derivatives of nucleic bases

A convenient method for the synthesis of 1,5-dihydroxy-3-oxa-2-pentyl derivatives of nucleic bases, which consists in the condensation of trimethylsilyl derivatives of nucleic bases with 1,2,5-triacetoxy-3-oxapentane in the presence of SnCl₄, is proposed. Optically active derivatives — (R)- and (S)-1-(1,5-dihydroxy-3-oxa-2-pentyl)uracil, respectively — were obtained by periodate oxidation of -L- and -D-arabinopyranosyluracil.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 223–228, February, 1988.     

Study of the rotational isomerism about the C-O bond in six-membered secondary-tertiary diols

We have determined the spectroscopic characteristics, the dipole moments, and the Kerr constants of the stereoisomers of the secondary-tertiary diols of the cyclohexane and bicyclo [4.1.0]pentane series: 3,4-dihydroxy-3-carane (I), 3,4-dihydroxy-3-methylnorcarane (II), 3,4-dihydroxy-3-methylnorcarane (III), 4, 5-dihydroxy-3-methylcyclohexene (IV), 3,4-dihydroxy-3-carane (V), 3,4-dihydroxy-3-methylnorcarane (VI), 3, 4-dihydroxy-3-carane (VII), and 3,4-dihydroxy-4-methyl-3-carane (VIII). It was found that the cis diols are more polar than their trans isomers. It was shown by electrical and electrooptical methods that rotamers with a gauche orientation with respect to the tertiary C-O are stable relative to those containing the diol at the ordinary C-C bond of the ring.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 619–625, March, 1991.     

Die Dissoziationskonstanten von 2,3′-und 2,4′-Dihydroxydiphenylmethanderivaten

The pK-values of the first and second degree of dissociation of 2.3-dihydroxy-6-methyl-3.5-dinitro-diphenylmethane, 2.3-dihydroxy-6-methyl-5-nitro-diphenylmethane, 2.3-dihydroxy-5.6-dimethyl-3-nitro-diphenylmethane, 2.4-dihydroxy-3. 5-dimethyl-3.5-dinitro-diphenylmethane, 2.4-dihydroxy-3. 5-dimethyl-5-nitro-diphenylmethane and 2.4-dihydroxy-3.5.5-trimethyl-3-nitrodiphenylmethane were determined in aqueous solution at 25°C by the spectrophotometric method. The observed pK-values are compared with those of 2-methyl-4.6-dinitro-phenol, 2-methyl-4-nitrophenol, 2.4-dimethyl-6-nitrophenol, 3.4-dimethylphenol and 2.4.6-trimethylphenol which serve as model compounds for the single phenolic units.     

Die Dissoziationskonstanten von 2,2′-Dihydroxydiphenylmethanderivaten

The pK-values of the first and second degree of dissociation of 2.2-dihydroxy-5-methyl-3.5-dinitro-diphenylmethane, 2.2-dihydroxy-5-methyl-5-nitro-diphenylmethane and 2.2-dihydroxy-5.5-dimethyl-3-nitro-diphenylmethane were determined in aqueous solution at 25°C spectrophotometrically. Comparing the observed pK-values with those of 2-methyl-4.6-dinitrophenol, 2-methyl-4-nitrophenol, 2.4-dimethyl-6-nitro-phenol and 2.4-dimethylphenol, we found a decrease of the values of pK ₁ and an increase of pK ₂. We explain this by the formation of an intramolecular hydrogen bridge which stabilizes the anion of the half dissociated form. This assumption is supported by the UV spectra.

---

---

Mit 3 Abbildungen     

Asymmetric hydrogenation of tryptophan precursors catalyzed by rhodium-DIOP complexes

Z-2-benzamido(acetamido)-3-(3-indolyl)-2-propenoic acids were hydrogenated with neutral and cationic rhodium(I) complexes containing the chiral diphosphine (–) or (+)–2,3-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)-butane [(–) or (+)–DIOP].

---

Z-2- ()-3-(3-)-2- () (I), (–) (+)-2,3--2,3--1,4- ()-.

     

Synthesen von N-substituterten o-Methylthioanilinderivaten

Zusammenfassung Methylierung von o-Aminothiophenol lieferte o-Methylmercapto-anilin, dessen Tosylat zur Herstellung des Tosylates der N-(o-Methylmercaptophenyl)--aminopropionsäure verwendet wurde. Cyclisierung von -(2-Methylmercaptodiphenyl)-aminopropionsäure ergab 1-(2-Methylmercaptophenyl)-4-oxo-1,2,3,4-tetrahydrochinolin, dessen Oxim zu 1-(2-Methylmercaptophenyl)-4-amino-1,2,3,4-tetrahydrochinolin reduziert wurde. N-[-(4-Methylpiperazinyl-1)-propyl]-2-methylthiodiphenylamin wurde durch Direktsubstitution van 2-Methylthio-diphenylamin erhalten.

---

Methylation of o-aminothiophenol gave o-methyl-mercaptoaniline, the tosylate of which was used for the preparation of N-(o-methylmercaptophenyl)--aminopropionic acid tosylate. Cyclization of -(2-methylmercapto-diphenyl)-aminopropionic acid yielded 1-(2-methylmercaptophenyl)-4-oxo-1,2,3,4-tetrahydroquinoline, the oxime of which was reduced to 1-(2-methylmercaptophenyl)-4-amino-1,2,3,4-tetrahydroquinoline. N-[-(4-Methylpiperazino-1)-propyl]-2-methylmercapto-diphenylamine was prepared by direct su stitution of 2-methylmercapto-diphenylamine.

     

Study of the evolution of a MoO3+Bi2MoO6 mixture in air and in the conditions of mild propene oxidation

MoO₃ can react with the gamma phase of bismuth molybdate (Bi₂MoO₆) in the conditions of propene oxidation to form the alpha phase (Bi₂Mo₃O₁₂) resulting in a more selective catalyst for propene oxidation to acrolein. Intimate contact between MoO₃ and the gamma phase is an important factor favoring the formation of the alpha phase.

---

MoO₃ - (Bi₂MoO₆), - (Bi₂Mo₃O₁₂), .

     

Liquid phase CO+H2 reactions in presence of ruthenium catalysts

Several effects on the hydrogenation of carbon monoxide in propanol in presence of ruthenium catalysts are examined. The homologation reaction is not observed, only propyl formate and propyl acetate are produced with any ruthenium catalyst. The pH-value is an important parameter: in acid media, the yield of propyl formate is noticeably increased indicating different catalytic active species. The addition of cesium salts is also benefitial for formate formation. This is not the case when water is associated with propanol as solvent. Finally, no ethylene glycol is detected. The process is found to be homogeneous and methanol seems to be the precursor of methyl formate.

---

, . , . : , . . , . . , -, .

     

Enthalpies of solution of thymine and uracil in water and dimethylsulfoxide

Enthalpies of solution of thymine and uracil in water and in dimethylsulfoxide (DMSO) were measured calorimetrically in the temperature range 25–40°C. H _s ^o at 25°C for thymine and uracil in water were found to be 23.1±0.5 and 29.5±0.3 kJ-mol^–1, respectively. In DMSO, H _s ^o were 7.9±0.1 and 10.2±0.1 kJ-mol^–1, respectively. In aqueous solution C _p ^o for the two nucleic acid bases were relatively large and positive with C _p ^o of thymine being larger. Both transfer quantities H _t ^o and C _p,t ^o for the proceses H₂ODMSO for the two nucleic acid bases were negative. It is proposed that, the differences in the values obtained for the two bases is due principally to increased order in the water adjacent to the methyl group in thymine.     

Influence of structural promoters on reduction dilatograms of iron catalyst

In each reduction step, changes in the catalyst pellet volume during reduction of precipitated iron catalysts are determined by the concentration of structural promoters and the reaction temperature.

---

, , .

     

Simple and effective method for the synthesis of 3′,5′-substituted 1-β-D-arabinofuranosyluracil

3,5-Substituted arabinofuranosyluracil is a starting compound in 2-modifications. A convenient and effective method is proposed for the synthesis of 1-(3,5-di-o-trityl--D-arabinofuranosyl)uracil by successive reactions of 2,2-cyclization of uridine, 3,5-tritylation of the 2,2-anhydrouridine, and hydrolytic cleavage of the 2,2-anhydro bond.Institute of Organic Synthesis, Riga LV-1006. Odense Universitet, Kemisk Institut, Odense, Denmark. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 975–977, July, 1996. Original article submitted April 25, 1996.     

n-Hexane dehydrocyclization on modified L-zeolite

Platinum dispersity and catalytic activity of L-zeolite-metal catalysts at 773 K have been studied depending on the nature of a modifying agent. The mean size of Pt particles is shown to decrease by a factor of 1.5–2 upon adding Re or W. No relation between Pt dispersity and activity in n-hexane dehydrocyclization has been revealed.

---

773 L . 1, 5–2 Re W. -.

     

Thermodynamics of α-Cyclodextrin Complexation with Bases of Nucleic Acids and Their Derivatives

The interactions of -cyclodextrin with adenine, thymine, uracil, cytosine, and caffeine in water at 298.15 K have been studied by the calorimetric method. -Cyclodextrin is found to interact selectively with nucleic bases and their derivatives to form complexes with uracil, cytosine, and caffeine only. The influence of the structure and solvation of the reactants on the thermodynamic characteristics of their complexation in a solution has been examined.     

Effect of the medium in hexacyanoferrate (III)-iodide and peroxodisulfate-iodide reaction

The kinetics of the two reactions hexacyanoferrate (III)-iodide and peroxodisulfate-iodide in several isodielectric water-cosolvent mixtures have been studied. The results can be rationalized as a consequence of the cosolventwater interaction.

---

(III) -. -.

     

The application of thermoanalytical methods in the investigation of biological substances

The equilibria and thermodynamics of a number of naturally occuring isolated compounds (e.g. proteins, amino acids, carbohydrates) have recently been studied in several laboraties in different temperature ranges, and thermoanalytical methods have been used to study structural changes of biological materials, among them human tissues.In our investigations we succeeded in appling the derivatograph for the assay of glycosaminoglycans and for the characterization of the stability of crosslinked proteins in intact human and animal tissues. By means of this method age-related and pathological changes and repair reactions were studied in various connective and vascular tissues.Other temperature-dependent techniques (DSC, polarizing microscopy) were used successfully in another series of experiments. Alterations in the characteristic order-disorder transition temperatures of human serum lipoproteins could be demonstrated in pathological conditions; the altered physical structure of lipoproteins might give an additional explanation to the assumed mechanism of different metabolic disorders.

---

Zusammenfassung Die Gleichgewichte und die Thermodynamik einer Reihe von natürlich vorkommenden isolierten Verbindungen (z. B. Proteine, Aminosäuren, Kohlenhydrate) wurden in verschiedenen Laboratorien in verschiedenen Temperaturbereichen untersucht. Hierbei wurden thermoanalytische Methoden zum Studium der Strukturänderungen von biologischem Material, u. a. von menschlichem Gewebe, eingesetzt.In unseren Untersuchungen gelang es den Derivatographen zur Prüfung von Glycosaminoglycanen und zur Charakterisierung der Stabilität quervernetzter Proteine in intakten menschlichen und tierischen Geweben einzusetzen. Durch diese Methode wurden altersbedingte und pathologische Änderungen sowie Reaktionen zur Wiederherstellung in verschiedenen Binde und Vasculärgeweben studiert.Andere temperaturabhängige Techniken (DSC, Polarisationsmikroskopie) wurden in anderen Versuchsserien mit Erfolg eingesetzt.

---

, . , , , , . . , . .

---

---

Plenary lecture     

Biosynthesis of asterosaponins from cholesterol and other sterols under the conditions ofin vitro homogenates of starfish gonads and pyloric ceca

Conditions have been selected for performing thein vitro biosynthesis of asterosaponins from cholesterol and other sterols in homogenates and cultures of the gonads and pyloric ceca of Far Eastern starfish. It has been shown that the aglycone moiety of an asterosaponin can be biosynthesized from cholesterol, cholesterol sulfate, 5-cholestanol, and 3,6-dihydroxy-5-cholestane but not from 3, 6-dihydroxy-5-cholestane. Of the give precursors studied, cholesterol was transformed into asterosaponins most completely.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 663–667, September–October, 1985.     

Interaction of nitric oxide with NiCr2O4

Interaction of NO with NiCr₂O₄ has been studied at 473–1173 K. It has been established that on nickel-chromium spinels NO decomposition practically does not take place. Nitric oxide can interact only with prereduced samples to reoxidize them.

---

473–1173 NO NiCr₂O₄. , NO . (II) ; .

     

Solid-state decomposition studies on fluoroperoxo species of transition metals part II

The kinetics of isothermal decomposition of solid K₂Zr₂(O₂)₂F₆·2H₂O have been studied in the temperature range 100–226° under vacuum. The fractional decomposition has been determined by measuring the pressure of evolved oxygen during pyrolysis with the help of a McLeod gauge. The values ranged from 0.05 to 0.62. The vs. t data showed that the kinetics are deceleratory throughout the course of the reaction. The initial part of the decomposition reaction could be best described by a unimolecular decay law, while the later stages obey contracting volume kinetics. The activation energies have been determined and the respective values for the above stages are 13.6 and 6.9 kcal·mole^–1.

---

Zusammenfassung Die Kinetik der isothermen Zersetzung von festen K₂Zr₂(O₂)₂F₆·2H₂O wurde im Temperaturbereich von 100–226° im Vakuum untersucht. Die fraktionierte Zersetzung wurde durch Messung des Druckes des während der Pyrolyse entwickelten Sauerstoffs mit einem McLeod-Manometer bestimmt. Die -Werte variierten von 0.05 bis 0.62. Die -t Daten zeigen, daß die Kinetik im Verlauf der Reaktion herabgesetzt wird. Der erste Teil der Zersetzungsreaktion konnte am besten durch ein unimolekulares Zerfallgesetzt beschrieben werden, während die späteren Phasen der Kinetik der Volumenkontraktion gehorchten. Die Aktivierungsenergien wurden berechnet und die entsprechenden Werte für obige Reaktionen ergaben sich 13.6 bzw. 6.9 Kcal mol^–1.

---

K₂Zr₂(O₂)₂F₆·2₂ 100–226°. «» , , . «» 0.05 0.62. –t , . , — . , , , 13.6 6.9 .^–1.

---

---

One of the authors (SMK) is grateful to I.I.T. Delhi for a research scholarship.