Fe-Catalyzed Novel Domino Isomerization/Cyclodehydration of Substituted 2-[(Indoline-3-ylidene)(methyl)]benzaldehyde Derivatives: An Efficient Approach toward Benzo[b]carbazole Derivatives

A new and efficient protocol to synthesize substituted benzo[b]carbazole derivatives has been demonstrated involving iron-catalyzed domino isomerization/cyclodehydration sequences from substituted 2-[(indoline-3-ylidene)(methyl)]benzaldehyde derivatives. The substrates could be easily made via Pd-catalyzed domino Heck-Suzuki coupling from 2-bromo-N-propargylanilide derivatives in high yields. Notably, the generality and efficiency of this two-stage domino strategy was further exemplified by the synthesis of a polycyclic benzofuran derivative.