An efficient Pd-catalyzed intramolecular cyclization reaction followed by formation of benzimidazole derivatives: Synthesis of novel quinolin-fused benzo[d] azeto[1,2-a]benzimidazole analogues

Abstract

Novel quinolin-fused benzo[d]azeto[1,2-a]benzimidazole analogues have been synthesized from o-phenylene diamine and various substituted 2-chloro-5-(2-methylquinoline-4-yl) benzaldehyde through Pd-mediated simultaneous CH–NH and CH–CX bond activation via intramolecular cyclization reaction followed by formation of benzimidazole derivatives. Developed two step, one pot route for quinoline fused four membered azeto[1,2-a] benzimidazole derivatives through Pd-catalyzed cross coupling reaction. The synthesis was carried out by using Pd₂(dba)₃ as a catalyst, Xphos as a ligand, Cs₂CO₃ as a base and toluene as a solvent and developed its mechanistic pathway.

Graphical Abstract

Keywords:

• Azetidine ring
• CH–NH and CH–CX bond activation
• intramolecular cyclization reaction
• Pd-catalyzed

Acknowledgements

We are grateful to Prof. N. B. Patel, Head of the Chemistry Department, Veer Narmad South Gujarat University, Surat for giving support and necessary lab facilities. The authors are also express their sincere thanks to the Indian Institute of Science Education and Research, Pune for spectral analysis.