Pyrylium[2,3-b]indole salts

2-Ketoindoline and 1-methyl-2-ketoindoline condense with hydroxymethylene ketones in the presence of hydrogen chloride to give pyrylium[2,3-b]indole chlorides, which can be converted to 5-(3-oxindolyl)-²-pyrazolines by reaction with phenylhydrazine and to 5-(3-oxindolyl)-²-isoxazolines by reaction with hydroxylamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1030–1032, August, 1972.     

Synthesis and reactions of benzo[b]furo[2,3-c]pyrylium salts

A method has been developed for the synthesis of 3-acetonyl- and 3-phenacylben-zo[b]furans by cyclization of 1-arloxy-2,4-pentanediones and 1-phenyl-4-aryloxy-1,3-butanediones in polyphosphoric acid. Acylation of 3-acetonyl(phenyl-benzo-[b]furans with aliphatic acid anhydrides in the presence of perchloric acid gives the benzo[b]furo[2,3-c]pyrylium perchlorates. The recyclization of the pyrylium salts with ammonia, aqueous alkali, and morpholine has been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–893, July, 1987.     

Synthesis and some reactions of selenopheno[2,3-c]pyrylium salts

The catalytic acylation and subsequent heterocyclization of -acetonyl derivatives of selenophene have been investigated. Methods have been proposed for the synthesis of new heteroaromatic systems: salts of the selenopheno[2,3-c]pyrylium cation and of selenopheno[2,3-c]pyridine. Methods have been developed for the synthesis of selenophene-3-carbaldehydes and 3-acetonylselenophenes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 918–922, July, 1973.     

Interaction of benzothieno[2,3-c]pyrylium salts with hydrazine. Derivatives of 5H-[2,3]benzothieno[2,3-e]diazepines

A study has been made of the reaction of 1,3-disubstituted bezothieno[2,3-c]pyrylium salts with hydrazine. It has been shown that 1,3-dialkyl-substituted benzothieno[2,3-c]pyrylium salts interact with hydrazine to give N-amino-1,3-dialkylbenzothieno[2,3-c]pyridines. The presence of a pyrylium ring on one of the positions of the phenyl group leads to a mixture of N-amino derivatives and 5H-[2,3]benzothieno[2,3-e]diazepines. In contrast, 1,3-diphenylbenzothieno[2,3-c]pyrylium perchlorate gives exclusively 5H-[2,3]benzothieno[2,3-e]diazepine.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Tar Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translate from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp 1137–1140, August, 1998.     

Recyclization of indolo[2,3-c]pyrylium salts by reaction with secondary amines

1-R-3-methylindolo[2,3-c]pyrylium salts react with cyclic secondary amines (morpholine, piperidine, and N-methylpiperazine) to give, depending on the structure of the alkyl substituent R, either 1- (when R=Me) or 3-aminocarbazoles (when R=i-Pr), or mixtures of both (when R=Et). The position of the amino-substituent in 1-morpholino-3,9-dimethylcarbazole has been established by x-ray diffraction examination.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 546–551, April, 1990.     

Synthesis of condensed derivatives of indolo[2,3-c]pyrylium salts and β-carbolines

Tetra- and pentacyclic indole [2,3-c] pyrylium salts were obtained by acylation of 2-(3-indolyl) dimedone and 2- (1-ethyl-3-indolyl)indan-1,3-dione. The latter salts by the action of ammonia are converted to the corresponding -carbolines — derivatives of the natural alkaloid harman.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 363–366, March, 1985.     

A simple synthesis of thieno[2,3-b]pyrazine and thieno[2,3-b] pyridine

A facile synthesis of thieno[2,3-b]pyrazine (1) and thieno[2,3-b]pyridine (9) is reported. Furthermore, convenient preparations of a variety of synthetically useful compounds derived from these ring systems is also presented.     

Polymethine dyes — Benzofuro[2,3-b]pyridine and selenonaphtheno[2,3-b]pyridine derivatives

Polymethine dyes — benzofuro[2,3-b]pyridine and selenonaphtheno[2,3-b]pyridine derivatives — were synthesized, and their spectral properties are discussed. Replacement of a vinylene group by an oxygen or selenium atom in one benzene ring of the 2-benzo[h]quinoline residue in the cyanines causes a large bathochromic shift of the absorption maxima of the dyes as compared with replacement by a sulfur atom. The dyes derived from benzofuro[2,3-b]pyridine derivatives are more deeply colored than the derivatives of both thionaphtheno[2,3-b]-pyridine and selenonaphtheno[2,3-b]pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp.1611–1614, December, 1972.     

Reactions of functionally substituted benzo[c]pyrylium salts. Synthesis of 5h-benzo-2,3-diazepines

5H-Benzo-2,3-diazepine derivatives are formed in the reaction of 4-ethoxycarbonylbenzo[c]pyrylium perchlorates with excess hydrazine hydrate. It was established that the key intermediate in the reaction is the 2-aminoisoquinolinium cation. A method for the recyclization of 4-cyanobenzo[c]pyrylium salts to 5H-benzo-2,3-diazepine derivatives was found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1477, November, 1993.     

Synthesis of functionally substituted benzo[c]pyrylium salts

Benzo[c]pyrylium salts that contain an acetyl, cyano, or ethoxycarbonyl group in the 4 position of the pyrylium ring were synthesized by the reaction of 3-(3,4-dimethoxyphenyl)pentane-2,4-dione and -(3,4-dimethoxyphenyl)acetoacetonitrile and ethyl -(3,4-dimethoxyphenyl)acetoacetate, as well as ethyl -(3,4-dimethoxyphenyl)benzoylacetate, with acyl perchlorates. It is shown that -(3,4-dimethoxyphenyl)acetoacetonitrile ethyleneketal is converted to 3-amino-4-acetylbenzo(c)pyrylium salts under these conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 465–470, April, 1990.     

2-arylfuro [2,3-b] quinoxalines

2-Arylfuro[2,3-b]quinoxalines were obtained by cyclization of 2-phenacyl-3-quinoxalones in the presence of polyphosphoric acid or a mixture of phosphorus oxychloride and phosphorus pentachloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–260, February, 1973.     

Polymethine dyes - 4-substituted furo [2,3-b]- and selenopheno[2,3-b]pyridine derivatives

Polymethine dyes that are 4-substituted furo[2, 3-b]pyridine and selenopheno-[2, 3-b] pyridine derivatives were synthesized. It was shown that replacement of the vinylene group in the benzene ring of a 4-quinoline heteroresidue in the cyanine dyes by an oxygen or selenium atom causes a greater hypsochromic shift in their absorption maxima than replacement by a sulfur atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 56–60, January, 1976.