Researches on aromatic heterocyclic compounds III. The aromatic character of piazthiol

The PMR spectra of piazthiol, which is benzo[1,2-c]-[1,2,5]-thiodiazole, and of its- and-nitro, chloro, methyl and amino derivatives are investigated. The effects of these substituents on the chemical shift is in qualitative agreement with the like effects in the benzene series. The parameters of the corresponding PMR spectra are greatly dependent on the electrophilic action of the heterocyclic ring. It is shown that there is conjugation in the thiadiazole ring, although, however, it is much weakened compared with that existing in the benzene ring.For Part II see [10].The authors thank V. F. Bystrov for discussions, and for making the double resonance measurements with-methylpiazthiol in a JNM-C-60 spectrometer.     

Researches on aromatic heterocyclic compounds III. The aromatic character of piazthiol

The PMR spectra of piazthiol, which is benzo[1,2-c]-[1,2,5]-thiodiazole, and of itsα- andβ-nitro, chloro, methyl and amino derivatives are investigated. The effects of these substituents on the chemical shift is in qualitative agreement with the like effects in the benzene series. The parameters of the corresponding PMR spectra are greatly dependent on the electrophilic action of the heterocyclic ring. It is shown that there is conjugation in the thiadiazole ring, although, however, it is much weakened compared with that existing in the benzene ring.     

The structure of the dinitromethyl anion in aromatic and heterocyclic compounds

It is shown experimentally that in salts of dinitromethyl derivatives of aromatic and heterocyclic compounds the nitro groups are equivalent, and participate equally in anion formation. It is shown that both in the free state, and as an anion, the dinitromethyl group in aromatic and heterocyclic compounds has just the same spectral characteristics as in aliphatic compounds. These characteristics can be utilized for analytical purposes. The IR spectra do not reveal conjugation between the mono- or dinitromethyl group and the benzene ring. Judging by the UV spectra the benzene ring is not conjugated with the dinitromethyl anion. It is found that in the solid state 2-dinitromethylpyridine is an internal salt.     

硒芳香杂环化合物的微波固相合成

许多含硒杂环化合物具有抗肿瘤、抗病毒等生物活性及超导性。微波技术由于能量利用率高,操作简便,无污染等优点,已在有机合成中得到了广泛的应用。本文采用微波辐射固相合成法合成了如下目标化合物：     

Allylboranes: reductive mono andtrans-diallylation of aromatic nitrogen-containing heterocyclic compounds

Reductive-mono- and stereoselective trans-,-diallylation of aromatic nitrogencontaining heterocycles by allylic boron derivatives have been discovered. A method for thetrans-to-cis isomerization oftrans-2,5-diallylpyrrolidines andtrans-2,6-diallyl-1,2,5,6-tetrahy-dropyridines by heating with allylboranes has been developed. The above reactions unite the chemistry of nitrogen-containing heterocycles and the chemistry of organoboron compounds on a new level.This review is based on a report presented at the conference INEOS-94: Modern problems of organometallic chemistry (May 21–27, 1994, Moscow).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1203–1216, July, 1995.The author is sincerely grateful to his colleagues E. A. Shagova, S. V. Evchenko, L. I. Lavrinovich, A. Yu. Zykov, E. V. Klimkina, and A. V. Ignatenko for their active participation in this work, as well as to M. E. Gurskii, I. D. Gridnev, and A. V. Geiderikh for useful advice and critical notes.This study was financially supported in part by the Russian Foundation for Basic Research (Grant No. 93-03-18193) and the International Science Foundation (Grant M3Y 000).     

Reactions of 1,3,3,3-tetrafluoro-2-methoxycarbonylpropenylsulfenyl chloride with aromatic and heterocyclic compounds

1,3,3,3-Tetrafluoro-2-methoxycarbonylpropenylsulfenyl chloride readily reacts with activated aromatic and heterocyclic compounds to form C-sulfenylation products as Å isomers. In some cases, its reactions with phenolic compounds are accompanied by cyclization giving rise to fused 2-(2,2,2-trifluoro-1-methoxycarbonylethylidene)-1,3-oxathioles.     

Introduction of the pyrylium ring into compounds of the aromatic and heterocyclic series

Halogen-substituted pyrylium cations react with organic nucleophilic compounds via an electrophilic mechanism to form new pyrylium salts. The reaction is extended to aromatic, heterocyclic, andnonbenzoid aromatic systems. Pyrylium salts that contain other functional groups do not enter into this reaction. The IR spectra of the compounds obtained are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1320–1323, October, 1971.     

Structural regularities governing sorption and gas chromatographic retention of aromatic nitrogen-containing heterocyclic compounds

The regularities governing differences in the gas chromatographic retention indices of aromatic nitrogen-containing heterocyclic compounds were studied during gas chromatographic analysis on a nonpolar capillary column. The retention indices of pyrrole, pyrazole, imidazole, 1,2,4-triazole, oxazole, thiazole, isoxazole, pyridine, pyridazine, pyrimidine, pyrazine, ands-triazine and their alkyl derivatives depend on the number, nature, and arrangement of heteroatoms and alkyl groups in the cycles. The majority of homologous series ofn-alkyl-substituted azoles and azines andn-alkylbenzenes is characterized by anomalously high differences between the retnetion indices of ethyl and methyl homologs. A scheme of calculation of retention indices of aromatic heterocyclic compounds from increments of heteroatoms was proposed.     

The analysis of some heterocyclic compounds

The mass spectra of some relatively simple sulphur compounds have been obtained. Comments upon the McLafferty rearrangement are reported.     

若干多氮硒杂环化合物在金表面的自组装及其电化学性质

研究了1,2,5-硒二唑并[3,4-b]吡啶（SPb）,1,2,5-硒二唑并[3,4-d]嘧啶-7-（5H,6H）酮（SPO）,1,2,5．硒二唑并[3,4．d]嘧啶-5,7-（4H,6H）二酮（SPDO）等多氮硒杂环化合物在溶液中及其在金表面的自组装单分子膜的电化学性质。以Fe（CN）6^3-/4-为离子探针,利用CV法观察了Fe（CN）6^3-/4-氧化还原峰的变化。结果表明,在溶液中,电极过程主受吸附控制;自组装膜的电化学信号与其溶液相似,在-600mV左右都有一还原峰,表明该类化合物有相似的组装模式,其中SPO和SPDO在金表面形成了致密的单分子膜,有效地封闭了表面与溶液之间的电子交换和传递。     

Thiomethylation of aromatic amines: efficient method for the synthesis of heterocyclic compounds

Primary aromatic amines were thiomethylated by formaldehyde and hydrogen sulfide. N-Substituted 1,3-thiazetidines, 4,5-dihydro-1,3,5-dithiazines, 3,4,5,6-tetrahydro-2H-1,3,5-thiadiazines, and 4,5-dihydro-1,3,5-oxathiazines were prepared for the first time starting from meta- and para-toluidines, meta-, para-, and ortho-anisidines, and para-xylidine. Amines characterized by higher mobility of hydrogen atoms produced previously unknown four-membered thiazetidines, whereas amines characterized by lower mobility of hydrogen atoms gave six-membered thiadiazines. The sorption properties with respect to silver were studied for the compounds, which were prepared from p-toluidine and p-anisidine.     

Quasi-linear fluorescence and phosphorescence of some aromatic and heterocyclic compounds in tetrahydrofuran at 77 K

The fluorescence and phosphorescence emission spectra of 31 polynuclear aromatic hydrocarbons and a number of heterocyclic compounds have been studied in tetrahydrofuran and in n-paraffin solvents at 77 K. A comparison of the characteristics of the quasi-linear luminescence emission observed in these solvents has been made. The effect of the presence of peroxide impurities in the tetrahydrofuran solvent on the emission spectrum observed for coronene has been investigated.     

Homolytic aromatic substitution by heterocyclic free radicals. Reaction of 3-quinolyl and 8-quinolyl radicals with aromatic compounds

Free radicals obtained from 3- and 8-aminoquinolines were studied in various aromatic substrates. Isomer percent, reaction yields, and overall reactivities towards benzene are recorded.     

Tropylation and pyrylation of salts of aliphatic mono-, di-, and trinitro compounds

We have studied the reactions of salts of nitroalkanes with tropylium and 2,6-diphenylpyrylium salts leading to products of C-tropylation and C-pyrylation of the corresponding anions. The only exception is the salt of cyanodinitromethane, which is not tropylated. Splitting off of a HNO₂ molecule from the products of tropylation of nitroalkane anions to prepare nitroheptafulvenes was unsuccessful.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2092–2097, September, 1991.     

Analysis of heterocyclic aromatic amines

Heterocyclic aromatic amines are formed in protein and amino acid-rich foods at temperatures above 150 °C. Of more than twenty heterocyclic aromatic amines identified ten have been shown to have carcinogenic potential. As nutritional hazards, their reliable determination in prepared food, their uptake and elimination in living organisms, including humans, and assessment of associated risks are important food-safety issues. The concentration in foods is normally in the low ng g⁻¹ range, which poses a challenge to the analytical chemist. Because of the complex nature of food matrixes, clean-up and enrichment of the extracts are also complex, usually involving both cation-exchange (propylsulfonic acid silica gel, PRS) and reversed-phase purification. The application of novel solid-phase extraction cartridges with a wettable apolar phase combined with cation-exchange characteristics simplified this process—both the polar and apolar heterocyclic aromatic amines were recovered in one fraction. Copper phthalocyanine trisulfonate bonded to cotton (“blue cotton”) or rayon, and molecular imprinted polymers have also been successfully used for one-step sample clean-up. For analysis of the heterocyclic aromatic amines, liquid chromatography with base-deactivated reversed-phase columns has been used, and, recently, semi-micro and capillary columns have been introduced. The photometric, fluorimetric, or electrochemical detectors used previously have been replaced by mass spectrometers. Increased specificity and sub-ppb sensitivities have been achieved by the use of the selected-reaction-monitoring mode of detection of advanced MS instrumentation, for example the triple quadrupole and Q-TOF instrument combination. Gas chromatography, also with mass-selective detection, has been used for specific applications; the extra derivatization step needed for volatilization has been balanced by the higher chromatographic resolution.     

Transport of some nitrogen heterocyclic and aromatic compounds through metal ion containing Nafion ionomer membrane

The permeation of some nitrogen heterocyclic bases, such as 1,10-phenanthroline, 2,2′-bipyridyl and 2-aminopyridine, and several aromatic compounds, namely styrene, toluene, nitrobenzene, aniline and biphenyl, through Nafion 117 ionomer membrane in H⁺, Na⁺, Cu²⁺ and Ag⁺ form has been studied. The permeation fluxes of the organic solutes through the membrane were measured by determining the concentration of the compounds in the sweep solutions using HPLC or flow injection technique. The positive role of metal ions in enhancing the permeation flux has been attributed to the complex formation of the solutes with the metal ions in the membrane. The contribution of the molecular structure of the permeates and steric effects are also discussed. The separation of some binary mixtures under favourable conditions is also shown.     

A new synthesis of n-acyl aromatic α-amino acids—amidoalkylation of aromatic and heterocyclic compounds with glyoxylic acid derivatives

The synthesis of N-acyl derivatives of aromatic α-amino acids 5 by the amidoalkylations of aromatic and heterocyclic compounds with glyoxylic acid amide adducts is described.     

Fluorosulfonyl-containing heterocyclic compounds

Hexafluoroisobutenylidene sulfate is a sulfotrioxidizing agent with respect to various olefins; methylenemethionic acid is formed in the case of ethylene, while the corresponding-sulfones are formed in the case of tetrafluoroethylene and vinylidene fluoride. 2,2-Difluoro-2-hydroxy-ethanesulfonic acid sultone is characterized by a capacity for anionotropic transformations; a number of sulfoacetic acid derivatives were obtained on the basis of this sultone.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 178–182, February, 1973.