Modular Synthesis of Di‐ and Triazadibenzoazulenes by a Cross‐Coupling/Cycloisomerization Strategy

Imidazo[1,2‐ a ]pyridines and imidazo[1,2‐ a ]pyrazines are important nitrogen‐containing heterocycles with applications in medicinal and materials chemistry. Herein, we report a regioselective synthetic strategy for the preparation of novel diaza‐ and triazadibenzoazulene derivatives through sequential Pd‐catalyzed Sonogashira and Suzuki–Miyaura cross‐coupling reactions, followed by Brønsted acid‐promoted cycloisomerization. The sequence of the cross‐coupling reactions enabled selective access to distinct regioisomeric intermediates, which were efficiently converted into fused seven‐membered azaazulene frameworks under optimized conditions. The methodology offers a broad substrate scope and affords the target compounds in good‐to‐excellent yields.