Sc(OTf) 3 -Mediated [4 + 2] Annulations of N -Carbonyl Aryldiazenes with Cyclopentadiene to Construct Cinnoline Derivatives: Azo-Povarov Reaction.

We disclose the first accomplishment of the azo-Povarov reaction involving Sc(OTf) 3 -catalyzed [4 + 2] annulations of N -carbonyl aryldiazenes with cyclopentadiene in chloroform, in which N -carbonyl aryldiazenes act as 4π-electron donors. Hence, this protocol offers a rapid access to an array of cinnoline derivatives in moderate to good yields for substrates over a wide scope. The synthetic potential of the protocol was achieved by the gram-scale reaction and further derivatization of the obtained polycyclic product.