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.