During the reproduction of the experiments described by Atta-ur-Rahman 1) we found that the reaction of 1-alkyl-8- carbolines (1) with excess dialkyl oxalates (2) between 155-175'C for 8-12 hours did not afford the pyrrolizine - derivatives described by the authors. However, canthin-alkaloid derivatives (3) were formed in one step with yields between 20-65 %. ... Compounds 2 have yellow colour and a green fluorescence under uv-lamp (254 and 366 nm). ...