Selective Synthesis of Fused N -Heterocycles or Polycyclic Aromatic Hydrocarbons via Tunable Mono or Double Carbene Insertion of Indazoles with Diazo Compounds

Herein, we disclose two distinct switchable reaction patterns of 3-aryl-1H-indazole with diazo arylidene succinimide. Under condition A, C–H-activation-initiated C–C/C–N bond formation via mono carbene insertion furnishes a fused N-heterocycle (indazolo[3,2-a]isoquinoline). Under condition B, C–H-activation-initiated triple C–C bond formation through double carbene insertion affords a polycyclic aromatic hydrocarbon (benzo[g]chrysene). To our knowledge, this is the first selective synthesis of these two valuable products from the same substrates. Interestingly, the benzo[g]chrysene derivatives thus obtained displayed bright fluorescence properties owing to the π-conjugation skeletons, suggesting their potential imaging and tracking capacity.