Double ortho-C-H Activation/Annulation of Benzamides with Aryl Alkynes: A Route to Double-Helical Polycyclic Heteroaromatics.

It remains a challenge to achieve N,O-double annulations of primary benzamides with aryl alkynes due to competitive N,N-double annulations. Herein, we employed sterically hindered 1-methylcyclohexane-1-carboxylic acid to address this challenge, the double ortho-C-H activation of benzamides and subsequent N,O-double annulations with aryl alkynes have been accomplished for the first time. The resulting product can be further transformed into a double-helical extended π-conjugated polycyclic heteroarene via Scholl oxidation, which exhibits blue emission with high fluorescence quantum yields.