Diazo compounds of the heterocyclic series

2-(N-Nitrosamino)benzimidazoles in aqueous solutions or in organic solvents are spontaneously converted to 1,3-di(2-benzimidazolyl)triazenes. Other methods for the synthesis of triazenes of the benzimidazole series and their properties are examined.     

Diazo compounds of the heterocyclic series

Stable primary N-nitrosamines of the benzimidazole series were obtained by the action of sodium amide and isoamyl nitrite on 1-substituted 2-aminobenzimidazoles and subsequent acidification of the resulting benzimidazole-2-diazotates. The effect of the acidity of the solution on the activity of the benzimidazole-2-diazonium salts formed from the nitrosamines was traced.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 689–692, May. 1974.     

The pyrylation of aromatic and heterocyclic compounds

Pyrylium salts having no substituents in position 4 react with aromatic and heteroaromatic compounds forming 4-aryl- and 4-heterylpyrylium derivatives. The reaction takes place through the stage of the formation of a pyran which, with an excess of the initial pyrylium salt, splits out a hydride ion, aromatizing into a trisubstituted pyrylium cation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 733–738, June, 1970.     

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：     

Researches on compounds with oxygen in the heterocyclic ring

Alkylation of furan and sylvan with 2-phenyl-2-chloropropane and cinnamyl chloride, and alkylation of sylvan with tert-butyl chloride in the presence of zinc chloride and zinc acetate are described.For Part IV see [1].     

Ring transformations of heterocyclic compounds. XI. 2,4,6-triarylphenylquinolinium salts from methyl substituted derivatives via (thio)pyrylium ring transformations

The preparation of hitherto unknown 2,4,6-triarylphenyl substituted quinolinium perchlorates 3 from methylquinolinium derivatives 2 by a 2,6-[C₅+C] ring transformation of 2,4,6-triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid is described. Spectroscopic data of the quinolinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.     

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.     

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.     

Reaction of pyrylium salts with heterocyclic amines

It has been established that in the reaction of 2, 4, 6-trimethylpyrylium perchlorate with 2-, 3-, and 4-aminopyridines, cytosine, adenine, guanine, and the corresponding nucleosides, and also with 2-amino-1-methylbenzimidazole, 2-amino-4-methylthiazole, 2-amino-4-phenylthiazole, 2-amino-6-bromobenzo-thiazole, and 2-amino-6-methoxybenzothiazole, either the corresponding quaternary pyridinium salt is formed or the pyrylium ring opens, depending on the basicity of the amino group.     

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.     

Ring transformations of heterocyclic compounds. X. A simple method for the conversion of methyl substituted pyridinium salts into 2,4,6-triarylphenyl derivatives: The first (thio)pyrylium ring transformations with heterocyclic anhydrobases as carbon nucleophiles

The synthesis of 2,4,6-triarylphenylpyridinium perchlorates 3 from methyl substituted derivatives 2 by a 2,6-[C₅+C] ring transformation of 2,4,6-triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid in ethanol is reported. Spectroscopic data of the pyridinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.     

Structure-mesomorphic activity relationship in the series of nitrogen-containing heterocyclic compounds

The structure-mesomorphic activity relationship was studied using the SARD (Structure Activity Relationship and Design) system for 300 nitrogen-containing heterocyclic compounds of which 178 compounds form a liquid crystal mesophase. Structural fragments exerting positive and negative effects on the manifestation of mesomorphic properties were revealed.     

Substituent interaction with ring sulfur in some heterocyclic compounds

The infrared carbonyl absorptions of 7-acetyl-1,2-benzisothiazoles are similar to 7-acetylbenzo[b]thiophenes, but are lower by approximately 15 cm^?1 than the corresponding benzo[b]furans. The reasons for this are discussed.     

Synthesis of pyrylium salts and pyridines containing heterocyclic substituents

A method of synthesizing pyrylium salts with heterocyclic substituents in the ring, has been investigated. The synthesis was carried out in two stages: alkaline condensation of aromatic and heterocyclic aldehydes with methyl ketones to give 1, 5-diketones, followed by cyclization to pyrylium salts by treatment with triphenylmethyl perchlorate. Pyridines containing heterocyclic substituents were obtained by treating the pyrylium salts with ammonia.