Synthesis of condensed pyrroloindoles via Pd-catalyzed intramolecular C-H bond functionalization of pyrroles.

A new strategy for the synthesis of condensed hetero- or carbocycles such as pyrroloindoles or fluorenes has been developed that involves the Pd-catalyzed cyclization of readily available N-(2-halobenzyl)pyrroles or their phenyl derivatives. The reaction is proposed to proceed via oxidative addition of benzylic halides to Pd(0) followed by base-assisted C-H bond activation. A broad range of condensed cyclic products could be obtained in good to excellent yields under mild conditions.