Bicyclization of Azomethine Ylide: Access to Highly Functionalized 3H-Pyrrolo[2,3-c]quinolines.

A tandem bicyclization of azomethine ylides with methyleneaminochalcones was developed for the straightforward and facile synthesis of 2-substituted polyfunctionalized pyrrolo[2,3-c]quinolines. Both an unusual reactivity profile of azomethine ylide and a novel strategy for the construction of the tricyclic framework by the successive construction of the pyridine and pyrrole rings were exhibited in this domino reaction. Two intermediates are isolated in the control experiments, and thus a tandem bicyclization/elimination/oxidative aromatization process is proposed for the reaction mechanism.