An attempt was made to synthesize 2-acetylindole by the conventional Fischer's method from the diacetyl monophenylhydrazone using polyphosphoric acid (PPA) as a condensing agent but the product isolated was proved to be 3-acetylindole.In order to explore the possibility that the migration of the acetyl group from the 2- to the 3-position could take place after the indole formation,the desired 2-acetylindole,which was synthesized by catalytic reduction of the 2-diazo-acetoindole,was treated with PPA,and the expected 3-acetylindole was success fully obtained.The structure of the 2-acetyl tompound was established by its infrared spectrum as well as its derivative formations.Although migration of an alkyl group in the indole ring with PPA as a condensing agent has previously been observed,the authors have not been aware of any migration of an acetyl group up to now.It is interesting to note in this connexion that Witkop and his coworkers have pointed out that "it seems probable that PPA will be useless for the preparation of a 2-unsubstituted indole".