Quinoxaline: a new directing group for ortho C-H alkenylation/intramolecular ortho C-H cycloamination under open air leading to bioactive polynuclear N-heteroarenes

Quinoxaline has been identified as a new directing group for the Pd (or Ru)-catalyzed ortho C-H alkenylation of aniline derivatives and subsequent hypervalent iodine promoted intramolecular ortho C-H cycloamination of the resulting N-arylquinoxalin-2-amine derivatives. This two-step strategy afforded alkenyl substituted benzo[4,5] imidazo [1,2-a] quinoxalines as inhibitors of PDE4. The Pd-catalyzed ortho C-H alkenylation of phenol derivatives was also performed successfully when quinoline was found to be an effective directing group.