Synthesis of unsaturated derivatives of 2,5-dimethyl-4-phenylpyridine and 3-methyl-2-azafluorene

A substituted butadiene — 1-phenyl-4-(5-methyl-4-phenyl-2-pyridyl)buta-1,3-diene with a trans, trans configuration — was obtained by condensation of 2,5-dimethyl-4-phenylpyridine with cinnamaldehyde. Two 3-methyl-9-cinnamylidene-2-azafluorene isomers are formed as a result of condensation of the same aldehyde with 3-methyl-2-azafluorene. Data from the PMR and IR spectra were used to prove the configuration of the compounds obtained. It was established that the condensation of 3-methyl-2-azafluorene with salicylaldehyde gives 3-methyl-9-(2-hydroxybenzylidene)-2-azafluorene, which has a zwitterionic structure, and 1,2-bis(3-methyl-2-aza-9-fluorenylidene)ethane. Ideas regarding the chemical mechanism of the formation of the latter are presented. The preparation of an unsaturated alcohol — 3-methyl-9-allyl-2-aza-9-fluorenol — is described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 82–86, January, 1978.     

Mass-spectrometric study of the cyclization reactions of diazoketones. 8. 1-Diazo-3,4-epoxy-4-arylbutan-2-ones

An analysis of the mass spectra of 1-diazo-3,4-epoxy-4-arylbutanones has shown that the molecular ions of these compounds lose a molecule of nitrogen and that the [M — N₂]⁺ ions formed cyclize to form hydroxyfuran structures, whose further fragmentation determines the whole picture of the dissociative ionization of the compounds investigated under electron impact. The majority of the [M — N₂]⁺ ions have the form of the cyclic intermediate formed in the first step of the cyclization process. It cannot, however, be ruled out that a certain portion of the [M — N₂]⁺ ions are stabilized as a result of a Wolff rearrangement and do not cyclize at all.For report 7 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 17–22, January, 1986.     

New reaction in the acridine series

A new reaction in the acridine series — reaction of its salt or the base with the salts or bases of N-heterocyclic compounds containing an active methyl group in the presence of sulfur — was investigated. It is shown that 9-acridinylheterylmethanes are formed as a result of this reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1384–1386, October, 1970.     

Saturated nitrogen-containing heterocycles. 13. Perhydroacridines. Synthesis and stereochemistry

The configurations of the perhydroacridines formed in the catalytic hydroamination of threo-methylenedicyclohexanone and the product of its cyclization — 2-hydroxy-2,3-tetramethylenebicyclo[3.3.1]nonan-9-one — were established by means of the ¹³C NMR spectra and alternative synthesis. It is shown that isomers with cis-anti-cis and cis-syn-cis configurations are formed as a result of the reactions. The results of x-ray diffraction analysis are presented for cis-syn-cis-N-(2-hydroxyethy1)perhydroacridine.See [1] for Communication 12.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1645–1650, December, 1987.     

Products of phototransformation of provitamins D4 obtained from a mutant Saccharomyces cerevisiae yeast. I. Irradiation in ethanol

The composition of the photolytic mixture formed on the irradiation of provitamin D₄ has been studied. Together with the main reaction products — vitamin D₄ and provitamin D₄ — a number of by-products were formed the structures of which have been established from their spectral characteristics.Lensoviet Leningrad Technological Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 247–254, March–April, 1989.     

Characterization of organic disulfides by paper electrophoresis after reduction to 2-alkyl(aryl)thio-1-methylpyrinium lodides

Summary A procedure is outlined that permits characterization of alkyl and aryl disulfides. The procedure utilizes the reduction of disulfides with lithium aluminium hydride or sodium bis(2-methoxyethoxy)aluminium hydride to the corresponding thiols followed by reaction with 2-chloro-1-methylpyridinium iodide. 2-Alkyl(aryl)thio-1-methyl-pyridinium iodides so formed are separated by high-voltage paper electrophoresis in boric acid — diethanolamine — EDTA buffer at pH 7.6; the relative mobilities measured after visualization with iodine vapor. Several disulfides, including primary, secondary, tertiary and aryl compounds, have been characterized in this way.Presented in part at the Ninth International Symposium on Organic Sulfur Chemistry, June 9–14, 1980, Riga, USSR.     

The first three aromatic tribromides of the [2.2]paracyclophane series

From the reaction mixtures in the uncatalyzed polybromination of [2.2]paracyclophane by the action of excess Br₂ in CCl₄, there have been found along with the known products — 4,15- and 4,16-dibromo[2.2]paracyclophanes — two new aromatic tribromides of this series, which have been isolated in pure form: 4,12,15- and 4,15,16-tribromo[2.2]paracyclophanes. Special experiments demonstrated that the mixtures of these tribromides are formed as a result of competitive monobromination of 4,15-dibromo[2.2]paracyclophane; the 4,15,16-tribromo[2.2]paracyclophane, together with still another newly isolated isomer of this series — 4,8,12-tribromo[2.2]paracyclophane — is formed as a result of competitive monobromination of 4,16-dibromo[2.2]paracyclophane. As an explanation of the features of the orienting effect of substituents in these competing reactions, a rule was proposed: On the conventional orientation (from the electronic point of view) of entry of the bromine atom into the substituted ring (para > ortho > meta), a steric limitation is imposed on its attack in the pseudo-gem-position, owing to the bulky bromine atom that is transannularly positioned above it in the neighboring aromatic ring. The structures of all of the tribromides were established on the basis of elemental analyses, mass spectrometry, and¹H NMR spectrometry (including PMR using the homonuclear Overhauser effect). The data obtained in this work indicate that the 4,12,15-tribromo[2.2]paracyclophane and 4,15,16-tribromo[2.2]paracyclophane are predecessors of the two tetrabromides previously obtained by Cram — 4,7,12,15- and 4,5,15,16-tetrabromo[2.2]paracyclophanes; and the 4,8,12-tribromo[2.2]paracyclophane is a possible predecessor of 4,8,12,16-tetrabromo[2.2]paracyclophane, which is unknown up to the present time.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1837–1843, August, 1992.     

Influence of Proton Transfer on the Formation of Hydrogen-Bonded Complexes of Higher Stoichiometry and on their Dissociation into Free Ions

Proton transfer in a given H-bond A—H—B—(H)A_–— H⁺—B—(H) considerably enhances the strength of the electron donor sites of the first partner and that of proton donor sites possibly present in the second one. This leads to the formation of complexes of higher stoichiometry of the type B— H⁺—(A^–—H—A--H—A--H--)or A^–---(H—B⁺—H----B—H—B—H----) where the self-association bonds are much strengthened. This is due to the high stability of the homoconjugated anions or cations in the corresponding ion pairs. In polar solvents like acetonitrile, the ion pairs may dissociate into free ions. The variety of the entities that can be formed necessitates a diversification of the quantitative concepts connected with the proton transfer process. Besides the average value x₁ of the fractions of the various complexes in the ionized form, other quantities are defined that can also be used in the case of partial dissociation: (1) the percentage of ionized base molecules and (2) the fraction of donor molecules AH ionized after direct interaction with B. A further characteristic used in this generalized treatment is the average number n of proton donor molecules perturbed by one base molecule. Examples of determinations of these various parameters from calorimetric, infrared, or NMR data from the literature are presented and new quantitative correlations established.     

Study of the formation and stability of the Pd and Pt metallic nanoparticles on carbon support

Catalysts containing Pd and Pt on a Sibunit carbon support were studied by the temperature-programmed reduction, in situ X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XAFS). The reduction of Pd and Pt species in samples 2%Pd/C and 2%Pt/C calcined in an air flow at 370°C was studied. Reduction of the 2%Pd/C sample begins at 50—60 °C and is completed at 250—300°C. Particles of various dispersion are formed during reduction. Long-distance peaks observed in the EXAFS spectra point to the presence of a fraction of relatively large crystallites. The average Pd—Pd coordination number (5) at 200 °C gives evidence that a number of very small Pd nanoparticles, oligomeric clusters, is present. Reduction at T > 200°C results in sintering of a small fraction of the Pd particles. Reduction of Pt in 2%Pt/C sample begins at 120—150 °C and is completed at 300—350°C. The sintering-resistant monodispersed Pt particles are formed under these conditions.     

Dehydrogenation of methanol on low Cu and Re—Cu catalysts supported on sibunite

The activity and selectivity of mono- and bimetallic catalysts containing copper and rhenium on sibunite were studied in the decomposition of methanol to methyl formate (MF), water, H₂, CO, and CO₂at 200—400 °C. Methane is also formed on rhenium-containing catalysts at 300—400 °C. The dehydrogenating activity and selectivity to form MF are higher on the copper-sibunite catalysts than on the rhenium-sibunite samples. The introduction of 0.25% Re into the 4% copper-containing catalyst enhances its total activity and stability.     

Synthesis and establishment of the structures of 5-hydroxy-and 8-hydroxy -2-(2-furyl) quinoxaline

Two condensation products — 5-hydroxy-2-(2'-furyl)quinoxaline and 8-hydroxy-2-(2-furyl)-quinoxaline — are formed in the reaction of 2-furylglyoxal or the sodium salt of its aldoxime with 6-hydroxy-1,2-diaminobenzene. Dielcometry was used to establish the position of the substituent in the benzene ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 306–310, March, 1976.Deceased.     

Anomalous products in the acylation of the dicobaltohexacarbonyl complex of 4-methylpenten-3-yne-1 with acryloyl tetrafluoroborate

Acylation of the dicobaltohexacarbonyl complex of 4-methylpenten-3-yne-1 with acryloyl tetrafluoroborate in a medium containing nitromethane with subsequent addition of a nucleophile (methanol or water) leads to anomalous products that are made up of two molecules of starting enyne and one fragment of acryloyl cation. On methanolysis a product of linear structure is formed — a functionally substituted undecane, and on hydrolysis a cyclic product is formed — a functionally substituted dihydropyran.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1875–1879, August, 1989.     

9-Alkylideneazafluorenes

A number of tertiary aza-9-fluorenols were obtained from 4- and 2-azafluofenones and were subjected to dehydration in order to synthesize the previously unknown 9-methyleneazafluorenes. The corresponding 9-methyleneazafluorenes and their polymers were obtained simultaneously in relatively stable form from both pyridine-ring-substituted and -unsubstituted 4-aza-9-fluorenols and from 1,3-diphenyl-2-aza-9-fluorenol. On the basis of an analysis of the mass spectrum of the polymer obtained from 9-methylene-4-azafluorene it was concluded that it is evidently isolated in the form of two dimers — dispiro [bis (4-aza-9-fluorene)-1, 3-cyclobutane] and the analogous product of dispiro addition with a 1,2-substituted cyclobutane ring. Condensation of the corresponding azafluorenes with benzaldehyde gave their 9-benzylidene derivatives in the form of geometrical isomers, the structures of which were established on the basis of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1234–1240, September, 1978.     

Reaction of 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene with hydrazines

2-Methyl-3-ethoxycarbonyl-4-(N,N-dimethylhydrazino)thiophene (II) and 2-methyl-3-ethoxy-carbonyl-4-(N-phenylhydrazino)thiophene (III) are formed by the action of substituted hydrazines — N,N-dimethylhydrazine and phenylhydrazine — on 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene (I). At the same time, the thiophene ring of hydroxythiophene I undergoes hydrazinolysis under the influence of hydrazine hydrate to form 3-mercaptomethyl-4-ethoxycarbonyl-5-methylpyrazole (IV). Structure IV was proved by IR, UV, and PMR spectroscopy and by hydrogenolysis of IV to the known 3,5-dimethyl-4-ethoxycarbonylpyrazole (V).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 759–761, June, 1971.     

Chromatographic characterization of a hexapeptide containing three thiol groups,intrinsic to the metallothionein structure

Summary The hexapeptide Lys-Cys-Thr-Cys-Cys-Ala [56–61] MT I is a molecule intrinsic to the metallothionein structure. Its chromatographic behaviour on a reversed-phase column, using electrochemical detection has been studied in order to get a better understanding of its chemical stability under various conditions. The chromatogram of the peptide consists of two peaks. The optimization procedure for their separation is presented and a hydrodynamic voltammogram has been generated. The relative proportion of the two peaks can vary with experimental conditions and is clearly dependent of the peptide concentration. Following the various experiments to which the peptide was submitted, namely elution after air oxidation, under inert atmosphere, in basic pH, after addition of an oxidizing agent (H₂O₂) and after addition of a reducing agent (2-mercaptoethanol), a reaction scheme was suggested: transformations of the reduced hexapeptide (three free thiol groups) into—as a first step—its intramolecular oxidized form (one SS bond, one free SH) and then into—as a second step—the fully oxidized dimeric form (no more free SH). Electrochemical detection allows a quantitative follow-up of the thiol oxidation and hence, of the disappearance of the reduced peptide.     

Monomer-Dimer Equilibrium of Rhodamine B Encapsulated in Si–Al and Si–Ti Binary-Oxide Thin Films

Si—Al and Si—Ti binary-oxide thin films including Rhodamine B (RB) have been prepared. They were dip-coated as a function of time after mixing of each sol-gel reaction system. The absorption and fluorescence spectra of the individual films have been observed. These spectra were analyzed in order to clarify the behavior of RB along with the change in the environment around the RB molecules, caused by the progress of the sol-gel reaction, in the fluid sol and the prepared thin films. Some amount of the RB dimers (H- and J-types) were formed in the Si—Al and Si—Ti binary-oxide films (Si : M = 75 : 25) prepared at the initial stage of the sol-gel reaction and aged under relative humidity of 60%. In the case of Si—Al binary-oxide films, the amount of the J-dimer decreased along with the reaction time at which the films were prepared, indicating that growing polymer networks of metal alkoxides around the RB molecules prevent the formation of the J-dimer. On the other hand, larger amounts of the H- and J-dimers were formed in the Si—Ti binary-oxide films prepared at longer reaction time of the solution. RB interacts more strongly with —TiOH compared with —AlOH. In the case of the Si—Ti binary-oxide films, with the progress of the sol-gel reaction, RB molecules in the prepared films easily cohere around the —TiOH and form the dimers because of increase in the amount of the —TiOH and contraction in the volume of the spaces where RB molecules exist.     

Insect pheromones and their analogs LVI. Chemical-enzymatic synthesis of (S)-(+)-9-hydroxydec-2E-enoic acid, a component of the queen pheromone of the honeybeeApis mellifera

(S,E)-(+)-9-Hydroxydec-2E-enoic acid—a component of the queen pheromones of the honeybeeApis mellifera — has been synthesized by the enzymatic reduction of 9-oxodec-2E-enoic acid with the aid of baker's yeast.Institute of Petrochemistry and Catalysis, Academy of Sciences of the Republic of Bashkortostan, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 877–879, November–December, 1997.     

Synthesis of 2-substituted tetrahydrofurans

We have developed a three-stage scheme for the preparative synthesis of 2-substituted tetrahydrofurans from allyl halides and aldehydes to give the first stage — a Grignard reaction — mixed alkoxides, which on treatment with acetic anhydride are converted to 4-acetoxy-1-alkenes. Addition of hydrogen bromide to the latter contrary to Markownikoff's rule gives 4-acetoxy-1-bromoalkanes, which as a result of hydrolysis form 2-R-tetrahydrofurans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1604–1607, December, 1988.     

Mass-spectrometric behavior of 9-hydroxy-10-nitrosophenanthrene and its diaza analogs

According to mass-spectral data, 9-hydroxy-10-nitrosophenanthrene in the gas phase exists primarily in this tautomeric form rather than in the 9-oxo-10-hydroxyimino tautomeric form, while passing to its 4,5-diaza and, particularly, its 1,8-diaza analogs shifts the equilibrium sharply to favor the o-quinoid form. The character of the fragmentation of the molecular ions of the polycyclic compounds differs markedly from the fragmentation of the acyclic rearrangement product — 2-carboxy-2'-cyanobiphenyl.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1518–1521, November, 1988.     

Synthesis of the acetate of (±)-2,6-dimethylhepta-1,5-dien-3-ol — The racemic form of the sex pheromone of Pseudococcus comstocki

4-Methylpent-3-enal has been synthesized by the dehydration of trans-2-(1-hydroxy-1-methylethyl)-1-methoxycyclopropane, and this has been brought into reaction with propen-2-ylmagnesium bromide. Acetylation of the carbinol so formed gave the acetate of (±)-2,6-dimethylhepta-1,5-diene-3-ol — the racemic form of the sex pheromone of the Comstock mealybug.Scientific-Research Institute of Physicochemical Problems, V. I. Lenin Belorussian University, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 747–748, September–October, 1988.