Synthesis of fused polycycles from propargylic compounds with terminal alkynes via a palladium-catalyzed tandem C-H activation/biscyclization process

Various benzo[b]fluorene and fluorene derivatives have been prepared from propargylic compounds with terminal alkynes through a novel palladium-catalyzed tandem biscyclization reaction. This reaction involved a sequence of carboannulation, coupling, C-H activation and C-C bond formation process. A plausible mechanism has been proposed that was consistent with the deuterium-labeling experiment.