Synthesis of indolo-α-pyrones, indolo-α-pyridones, and indolopyrylium salts
A method has been developed for obtaining indolo-α-pyrones by acylation of 3-indolylacetic acid and its N-methyl derivatives. Indolo-α-pyrones form indolo-α-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.