TBAB-catalyzed assisted C-C/C-N bond formations: An efficient approach to dihydrobenzo[b][1,8]naphthyridin derivatives via metal free Cascade annulation

An eco-friendly, metal-free approach for synthesizing dihydrobenzo[b][1,8]naphthyridine derivatives has been established. This method employs ortho-chloroquinolin-α,β-unsaturated ketones as dipolarophiles and acyclic enaminones as amphiphilic nucleophiles, enabling a formal [3 + 3] annulation reaction under phase-transfer catalysis to offed the targeted products. It boasts transition-metal-free conditions, broad functional group compatibility, and straightforward operational procedures.