Oxidative Radical Relay Functionalization for the Synthesis of Benzimidazo[2,1‐a]iso‐quinolin‐6(5H)‐ones

Abstract

Here, a mild and general oxidative radical relay carbocyclization reaction with 2‐arylbenzoimidazoles and cyclic ethers is reported. This method provides an efficient access to a wide range of structurally diverse benzimidazo[2,1‐a]isoquinoline‐6(5H)‐ones under metal‐free conditions. The wide substrate scope, good functional group tolerance, and scale‐up operation of this method are expected to promote its potential applications in biotechnology and pharmacy.magnified image

Electrochemically-mediated C–H functionalization of allenes and 1,3-dicarbonyl compounds to construct tetrasubstituted furans

“…The synthesis of polysubstituted heterocyclic molecules is a topic of continued interest due to their wide applications. [1][2][3][4][5] Tetrasubstituted furans are a significant heterocyclic compound, which have been extensively considered as key structural units in many biologically active natural products, pharmaceutical molecules and organic functional materials. 6,7 These valuable tetrasubstituted furan derivatives can be synthesized by two methods: one is the functionalization of existing furan rings, 8,9 and the other is the cyclization of acyclic substrates to construct furan rings.…”

Transition‐Metal‐Free Radical Cyclization of 2‐Arylbenzoimidazoles with Unactivated AlkanesviaC(sp3)−H Functionalizations in Aqueous Media

“…In sharp contrast, there is only one case in which C ‐centered radical is generated by the C( sp 3 )−H bond cleavage. Sun, Zhang, Zhang, and co‐workers successfully exhibited the cleavage of O ‐ ortho ‐C( sp 3 )−H bond of tetrahydrofuran (THF) to generate C ‐centered radical under the oxidation of benzoyl peroxide (BPO), and then C ‐centered radical underwent radical cyclization with 2‐arylbenzoimidazoles (Scheme 1b) [5] . However, it is worth noting that BPO may produce acid to make the post‐processing troublesome and THF is not considered as a green solvent [6] .…”

“…Sun, Zhang, Zhang, and co-workers successfully exhibited the cleavage of Oortho-C(sp 3 )À H bond of tetrahydrofuran (THF) to generate C-centered radical under the oxidation of benzoyl peroxide (BPO), and then C-centered radical underwent radical cyclization with 2-arylbenzoimidazoles (Scheme 1b). [5] However, it is worth noting that BPO may produce acid to make the post-processing troublesome and THF is not considered as a green solvent. [6] Meanwhile, this reaction is limited to oxygen atom adjacent C(sp 3 )À H functionalization, probably owing to the activation of C(sp 3 )À H bonds by oxygen atom adjacent.…”

Redox-Neutral Photocatalytic Radical Cascade Cyclization for the Synthesis of CH2CN/CF2COOEt/CF3-Containing Benzo[4,5]imidazo[2,1-a]isoquinolin-6(5H)-One Derivatives

“…The distance from the light source to the irradiation vessel was about 4 cm. The starting materials 2 were obtained from commercial suppliers and starting materials 1 were prepared according to the reported procedures. ,, …”