Bischler-Napieralski Synthesis of Polycyclic N-Heteroaromatics Based on Tf 2 O-Promoted Electrophilic Activation of N -Aryl-2-Propynamides.

2-Propynamides have been never used as substrates in classic and Tf 2 O-promoted Bischler-Napieralski reactions. In this article, a novel tandem synthesis of benzo[ a ]acridines is developed from N -aryl-2-propynamides and alkynes consisting of a Tf 2 O-promoted intermolecular Bischler-Napieralski reaction and a TfOH-promoted intramolecular Friedel-Crafts reaction.