2-Benzopyrylium salts

The interaction of 6,7-dimethoxy-3-(3,4-dimethoxyphenyl)-2-benzopyrylium perchlorate with -aminocarbonyl compounds forms N--aminocarbonyl-substituted isoquinolinium compounds which on treatment with acids are converted into dibenzo [a,g] quinolizinium compounds, one of which is the natural alkaloid dehydronorcoraldine. The products were characterized by the results of elementary analysis and IR, PMR, and UV spectroscopy.For Communication XXXIV, see [1].Scientific-Research Institute of Physical and Organic Chemistry, N. A. Suslov Rostov State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–80, January–February, 1989.     

2-Benzopyrylium salts

The previously unknown oxabenzo[c]phenanthrenium salts were synthesized from -veratryl-naphthol and its acetate.See [1] for communication XVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 745–747, June, 1976.     

2-Benzopyrylium salts

Oxoniachrysene salts, which on reaction with bases form either addition products or undergo anomalous cleavage of the heteroring bond, were obtained from papaverine methiodide.See [1] for communication XX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1176–1179, September, 1977.     

2-Benzopyrylium salts

The synthesis of berberine analogs — substituted dibenzo[a,g]quinolizinium salts — was worked out on the basis of 2-benzopyrylium salts.See [1] for communication XXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1481–1483, November, 1977.     

2-Benzopyrylium salts

2-Veratryl-5,6-dimethoxyindanone and 2-veratrylindane-1,3-dione, respectively, were obtained by intramolecular acylation ofα,β-diveratrylpropionic acid and condensation of veratraldehyde with phthalide in strongly alkaline media. A method was worked out for the synthesis of indeno[1,2-c]-2-benzopyrylium salts, from which indeno[1,2-c]isoquinolines are formed in good yields.     

2-Benzopyrylium salts

The condensation of 1-alkyl-3-carbalkoxy-2-benzopyrylium salts with diamines leads to the synthesis of piperazino[3,4-b]- and quinoxalino[3,4-b]isoquinolinium perchlorates.     

2-Benzopyrylium salts

The acylation of esters of 3,4-dimethoxyphenylpyruvic acid with anhydrides of aliphatic acids in the presence of 70% HClO₄ leads to the formation of 3-alkoxycarbonyl-1-alkyl-6,7-dimethoxy-2-benzopyrylium salts which, on being boiled with sodium acetate inglacial acetic acid, are converted into 3-alkoxycarbonyl-1-alkyl-6,7-dimethoxyisoquinolines.For Communication XIII, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1458–1460, November, 1973.     

2-Benzopyrylium salts

The properties of 1,3-dimethyl-6,7-dialkoxy-2-benzopyrylium salts were studied. The heterocyclic oxygen atom is readily replaced by nitrogen by reaction of the 2-benzopyrylium salts with primary amines, hydrazine, phenylhydrazine, glycine ethyl ester, and hydroxylamine; reaction with secondary amines leads to naphthalene derivatives. The activities of the methyl groups in the 1 and 3 positions of the heterocyclic ring are compared.For Communication IX, see [6].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1308–1312, October, 1970.     

2-Benzopyrylium salts

The reaction of alkyl and aryl benzyl ketones with acetals of aliphatic, aromatic, and heterocyclic aldehydes in the presence of triphenylmethyl perchlorate leads to 2-benzopyrylium perchlorates with substituents in positions 1, 3, 6, and 7. The influence of substituents in the benzyl ketones and the acetals on the ease of formation of the salts has been studied. The mechanism of the reaction is discussed.For communication XII, see [2].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 881–884, July, 1973.     

2-Benzopyrylium salts

-Veratrylindanones were obtained by reaction of -veratrylcinnamic acid with veratrole in polyphosphoric acid (PPA). A method for the synthesis of indeno-2-benzopyrylium salts based on acylation of the indanones with the free acids and their anhydrides was developed. It was shown that indeno-2-benzopyrylium salts can be converted to the little-studied indeno[1,2-c]isoquinoline bases.See [1] for communication XIV.Translated from Khimiya Geterotsiklicheskii Soedinenii, No. 2, pp. 181–183, February, 1974.     

2-Benzopyrylium salts.

The addition of azomethines to 2-benzopyrylium salts, which leads to derivatives of 3,4-dihydroisoquinolinium salts, was observed. An assumption regarding the mechanism of the reaction is expressed on the basis of its stereoselectivity. Dehydrogenation of the compounds obtained to completely aromatic isoquinolinium salts and reduction to tetrahydroisoquinolines were realized.See [1] for Communication 39.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1177–1180, September, 1990.     

2-Benzopyrylium salts. 25. Reaction of 2-benzopyrylium salts with some nucleophiles

The reaction of 2-benzopyrylium salts with various amines was studied, and it was established that the structure of the reaction product is determined not only by the structure of the starting salt but also by the nature of the nucleophilic reagent.See [1] for Communication 24.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1608–1611, December, 1981.     

2-Benzopyrylium salts. 42. Ortho-quinoid intermediates in recyclization reactions of 2-benzopyrylium salts

The interaction of 1-styryl-substituted 2-benzopyrylium salts with morpholine, methylamine, and malononitrile is highly stereoselective informing cis-3,4-dihydronaphthalenes; this can be taken as evidence that ortho-quinoid intermediates participate in these conversions.For Communication 41, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1468–1475, November, 1991.     

2-Benzopyrylium salts. 26. Recyclization of 2-benzopyrylium salts to α-naphthols

The behavior of 2-benzopyrylium salts with a CH₂ group in the 1 position at pH 7 was studied, and it was established that they undergo recyclization to -naphthols under these conditions. A mechanism for the conversion is proposed. One of the intermediates, viz., 3-hydroxy-1-tetralone, was isolated.See [1] for communication 25.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1184–1187, September, 1982.     

2-Benzopyrylium salts. 27. Formation of substituted chrysenes from 1-methyl-2-benzopyrylium salts

1-Methyl-2-benzopyrylium salts with a free position of the heteroring primarily form substituted chrysenes. In alkaline media this process does not proceed through the intermediate formation of 1,5-diketones.For Communication 26, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1472–1476, November, 1984.     

2-Benzopyrylium salts containing thiophene substituents in positions 1 and 3

2-Benzopyrylium salts containing heterocyclic substituents have not previously been known. In order to obtain 2-benzopyrylium salts containing thiophene substituents in position 3, we have studied the acylation of 3,4-dimethoxybenzyl 2-thienyl ketone (I), which was obtained with a yield of 36% by the acylation of thiophene (at 75° C) with homoveratric acid in the presence of polyphosphoric acid (PPA). Compound I forms yellow crystals with mp 74–75° C (from benzene), bp 220° C (6mm). Found %: C 63.40; H 5.38; S 13.55. C₁₁H₁₃O₃S. Calculated %: C 64.12; H 5.34; S13.21.Translated from Khimiya Geterotsiklicheskikh Soedinenii.Vol. 6, No. 7, pp. 1003–1004, July, 1970.     

2-Benzopyrylium salts. 43. Conversion of dimers of 2-benzopyrylium salts to benzofuran derivatives

In the acid-catalyzed interaction of dimers of 2-benzopyrylium salts with peracetic acid and hydrogen peroxide, the oxidation products that are formed are readily converted to benzofuran derivatives.For Communication 42, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 169–172, February, 1992.     

2-Benzopyrylium salts. 36. Disproportionation of 2-benzopyrylium salts through prior 4-1′ dimerization

It was observed that the disproportionation of 2-benzopyrylium salts proceeds through prior dimerization. Intermediates were isolated and identified. Assumptions regarding the mechanism of the transformation are expressed.See [1] for Communication 35.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 750–754, June, 1989.     

2-Benzopyrylium salts. 34. Reactions of 3-carboxy-2-benzopyrylium salts with amines. Synthesis of cyclic ketols

3-Carboxy-2-benzopyrylium salts form 3-carboxyisoquinolinium salts, their decarboxylated analogs, or products of contraction of the heterocycle, namely, cyclic ketols, depending on the nature of the amine and solvent. Upon treatment with acids, these ketols are demethylated through the intermediate formation of -acylcarbenium ions and are converted to quinonemethides.For communication 33, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 454–459, April, 1989.     

2-Benzopyrylium salts. 27. Some transformations of 6-oxodibenzo[a,g]-quinolizinium salts

The synthesis of 6-oxodibenzo[a,g]quinolizinium perchlorate — an analog of the alkaloid berberine — and a number of its derivatives, including mesoionic compounds, was accomplished on the basis of a 1-unsubstituted 3-(2-methylenecarboxyaryl)-2-benzopyrylium salt. The interconversions of the compounds obtained in this research were studied.See [1] for communication 26.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1381–1387, October, 1982.