Study On Radical Cascade Carbocyclization For The Synthesis Of Benzimidazole [2,1-a] Isoquinolines Derivatives

Nitrogen-containing heterocycles are widely found in natural products,pharmaceutical molecules and functional materials.Among them,benzimidazo[2,1-a]isoquinoline derivatives containing fused five-and six-membered rings frameworks,which are widely found in bioactive molecules and functional materials,are important structural fragments in chemical biology and materials science.Therefore,the development of simple and efficient new methods for the construction of benzimidazo[2,1-a]isoquinolines in accordance with green chemistry and atomic economy has attracted a great deal of attention from chemists.In view of the importance of the benzimidazo[2,1-a]isoquinoline motif,it is reviewed in the first chapter of this paper.the first chapter of provides an overview of the synthesis of benzimidazo[2,1-a]isoquinoline derivatives from three aspects:intramolecular C-N and C-C bond coupling cyclization reactions,intermolecular transition metal-catalyzed C-X（halide）and C-H bond activation reactions and intermolecular radical-induced cascade carbocyclization reactions.These studies not only provide an effective method for the synthesis of functionally rich polycyclic benzimidazo[2,1-a]isoquinoline skeletons,but also provide insights for exploring other new reaction modes.Free radical chemistries are attractive for synthesis because of their ability to exclusively synthesize highly complex and usually polycyclic molecular skeletons.The experiments are based on the high reactivity of radical species,driven by energy barriers,to induce selective C-C and C-H bond breaks for radical cascade cyclization reactions,simple and efficient construction of structurally diverse benzimidazoisoquinoline derivatives.The second chapter focuses on the carbon centered radical cascade cyclization reaction without metal participation,successful synthesis of ether-and aryl-containing tetracyclic benzimidazo[2,1-a]isoquinolin-6（5H）-ones derivatives under solvent modulation.The three chapter develops a practical copper-catalyzed radical cascade carbocyclization for synthesis of CF₃-containing tetracyclic benzimidazo[2,1-a]isoquinolin-6（5H）-ones.This practical oxidative radical cascade cyclization strategy is characterized by ease of operation,wide range of substrates,and mild reaction conditions for easy scale-up.These results may provide reference for solving related problems in the field of organic free radical chemistry,and may also provide convenient and practical synthetic tools for research in the fields of chemistry,biology and materials.