Palladium-Catalyzed Annulation of Phenazastannines with 9-(Dibromomethylene)fluorene and -(thio)xanthenes: Facile Synthesis of Acridine Moiety-Containing Bis(tricyclic) Aromatic Enes

Growing interest has been paid to bis(tricyclic) aromatic enes as key components of functional organic materials such as molecular switches and charge-transporting materials. Currently, the synthetic approaches to the overcrowded alkenes are limited to McMurry coupling and Barton–Kellog olefination. This communication reports that palladium-catalyzed double cross-coupling reaction of phenazastannines with 9-(dibromomethylene)fluorene, -xanthene, -thioxanthene, and -thioxanthene-S,S-dioxide serves as a facile synthetic approach to bis(tricyclic) aromatic enes such as 9-(9H-fluoren-9-ylidene)acridines, 9-(9H-oxanthen-9-ylidene)acridines, 9-(9H-thioxanthen-9-ylidene)acridines, and 9-(10,10-dioxido-9H-thioxanthen-9-ylidene)acridines.