Metal-free Microwave-Assisted Azo-Povarov Reaction of N-Carbony Aryldiazenes with trans-Cyclooctene to access Ring-fused Cinnolines

A previously undescribed azo-Povarov reaction between N-carbonyl aryldiazenes with trans-cyclooctene is developed. The participation of these aryldiazenes in the uncatalysed [4 + 2] annulation reaction has been applied to the construction of a variety of appealing fused cinnoline derivatives in yields ranging from 34 to 91% for substrates over a broad scope. The starting materials are cost-effective and easily accessible, while the reaction conditions and procedures are simple, requiring no external catalysts. Moreover, the synthetic significance of this methodology has been evidenced by a gram-scale azo-Povarov reaction and further derivatizations of the resulting N-containing heterocycles.