Synthesis of 3-acylamino- and 3-carbethoxy-2-benzopyrylium salts

High yields of 3-acylamino-2-benzopyrylium salts are formed in the acylation of 3,4-dimethoxy- and 3,4-methylenedioxyphenylacetonitrile. The salts are converted to 4-isoquinolones on treatment with ammonia. The acylation of ethyl 3,4-dimethoxyphenylglycidate ester also results in heterocyclization to 3-carbethoxy-2-benzopyrylium salts, which are converted to high yields of the corresponding 3-carbethoxyisoquinolines by treatment with ammonium hydroxide. The mechanisms of these transformations are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 730–732, June, 1971.