I. V. Shcherbakova

2-Benzopyrylium salts

Abstract2-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. 26. Recyclization of 2-benzopyrylium salts to ?-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 α-naphthols under these conditions. A mechanism for the conversion is proposed. One of the intermediates, viz., 3-hydroxy-1-tetralone, was isolated.

2-Benzopyrilium salts. 30. Synthesis and properties of 2-benzopyrilium salts with the 2,6-di-t-butylphenyl substituent in position 3

We achieved the synthesis of 2-benzopyrilium salts with a 2,6-di-t-butylphenyl substituent in position 3 by acylation of 3,5-di-t-butyl-4-hydroxy-3′,4′-dimethoxydesoxybenzoin. We carried out a comparison of the concurrent deprotonation of 1-methylene and hydroxyl groups in these salts and obtained the corresponding isoquinoline bases.

2-Benzopyrylium salts. 24. Synthesis and reactions of 3-(2-methylenecarboxyaryl)-2-benzopyrylium salts with amines

Abstract5-Oxoniachrysene and N-methylisoquinolinium perchlorates and substituted 1-naphthylamines were synthesized on the basis of 1-R-3-(2-methylenecarboxyaryl)-2-benzopyrylium salts.

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.

2-Benzopyrylium salts: XIX. Synthesis of oxabenzo[c]phenanthrenium salts

The previously unknown oxabenzo[c]phenanthrenium salts were synthesized from β-veratryl-αnaphthol and its acetate.

2-Benzopyrlium salts. XVIII. Synthesis of 2-benzopyrylium salts based on some enol acylates

The fundamental possibility of the synthesis of 2-benzopyrylium salts by intramolecular cyclization of enol acylates of suitable structure is shown. An assumption is made regarding the mechanism of the formation of pyrylium salts from enol acetates in the presence of acylating agents.