Preparation of Benzo[a]fluorenes via Pd-Catalyzed Annulation of 5-(2-Bromophenyl)pent-3-en-1-ynes

A palladium-promoted cascade cyclization of 5-(2-bromophenyl)pent-3-en-1-ynes is developed for the synthesis of benzo[a]fluorene derivatives. The reaction proceeds with oxidative addition of C–Br, insertion, C–H activation, and reductive elimination in sequential steps.