Synthesis of indolo-α-pyrones,indolo-α-pyridones,and indolopyrylium salts

A method has been developed for obtaining indolo--pyrones by acylation of 3-indolylacetic acid and its N-methyl derivatives. Indolo--pyrones form indolo--pyridones by refluxing with ammonium acetate in acetic acid. Indolo[2,3-c]pyrylium salts were obtained by acylation of 4-methoxyand 3,4-dimethoxy-3-phenacylindoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 345–349, March, 1971.