Unprecedented SnCl2·2H2O-mediated intramolecular cyclization of nitroarenes via C–N bond formation: a new entry to the synthesis of cryptotackieine and related skeletons

A mild, efficient, and one-pot protocol for the intramolecular cyclization of 2-substituted nitroarenes via C–N bond formation using SnCl2·2H2O is described. The versatility of the method has been demonstrated by synthesizing two sets of polycyclic structures based on privileged structures of indole and pyrrole, and of the alkaloid cryptotackieine associated with antimalarial activity. Our new approach provides a powerful entry into polycyclic structures related to an alkaloid.