Synthesis of 9-fluorenylidenes and 9,10-phenanthrenes through palladium-catalyzed aryne annulation by o-halostyrenes and o-halo allylic benzenes.

A number of functionally substituted 9-fluorenylidenes and 9,10-phenanthrenes have been synthesized from substituted o-halostyrenes and o-halo allylic benzenes respectively in good yields by the palladium-catalyzed annulation of arynes. The methodology tolerates a variety of functional groups, including cyano, ester, aldehyde, and ketone groups, occurs under relatively mild reaction conditions, and involves the generation of two new carbon-carbon bonds, thus providing these important carbocyclic ring systems in a single synthetic step.