Synthesis and Photophysical Study of Heteropolycyclic and Carbazole Motif: Nickel-Catalyzed Chelate-Assisted Cascade C–H Activations/Annulations

Herein, nickel-catalyzed synthesis
of polyarylcarbazole through
sequential C–H bond activations has been described. Regioselective
indole C2/C3 functionalization has been achieved in the presence of
indole C7-H, which is quite challenging. In addition, this approach
also gives easy access to building a heteropolycyclic motif through
C6/C7 C–H functionalization of indoline. This methodology is
not limited to aromatic internal alkynes as coupling partners; aliphatic
alkynes have also shown good tolerance. Notably, during the optimization
the catalytic enhancement with sodium iodide as an additive has been
observed. We have also studied the photophysical properties of these
highly conjugated molecules.