A highly efficient [3+2] cyclization between 4-aminopyridinones and acenaphthenequinone: Access to novel acenaph-tho[1,2':4,5]pyrrolo [3,2-c]pyridin-11-ones

Direct and metal-free access to poly-substituted acenaphtho[1 ',2':4,5]pyrrolo[3,2-c]pyridin-11-one and its analogs was established through a simple one-pot reaction using enaminones and acenaphthylene-1,2-dione as basic substrates. The reaction allows the formation of C-N and C-C bonds accompanied by multiple bond cleavage in the presence of acetic acid. The approach features atomic economy, broad substrate scope, efficient and metal-free reaction conditions, inexpensive and readily available starting materials and easy operation, making the strategy highly attractive. Importantly, the new acenaphtho[1 ',2':4,5]pyrrolo[3,2-c]pyridin-11-ones with hydroxyl substituents could be further functionalized, affording access to molecular complexity and diversity.