Stability and Resonance Energy of Annulated 1-Azaazulenes

The stability and resonance energy of heterocycle-annulated 1-azaazulenes such as cyclohepta[4,5]pyrrolo[1,2-a]imidazole (5a) and 12-methoxy-5H-cyclohepta[4,5]pyrrolo[2,3-b][1,5]benzodiazepine (7) were elucidated by means of Aihara’s TRE and Gimarc’s TCS rule. These compounds are predicted to be aromatic with positive resonance energies and in conformity with the TCS rule.