Synthesis of Polyaromatic Rings: Rh(III)-Catalyzed [5 + 1] Annulation of Enaminones with Vinyl Esters through C-H Bond Functionalization.

An expedient [5 + 1] annulation method via Rh(III)-catalyzed C-H bond functionalization of enaminones to synthesize polyaromatic rings is described. The reaction tolerates a broad range of functional groups and offers a new entry to construct polycyclic aromatic compounds with amino and formyl substituents. A possible reaction mechanism was proposed based on the results obtained from isotope labeling experiments.