Rhodium-Catalyzed Tandem Acylmethylation/Annulation Reactions of 2-Aryl-2H-indazoles with Sulfoxonium Ylides: Easy Access to 6-Arylindazolo[2,3-a]quinolines

An efficient synthesis of 6-arylindazolo[2,3-alpha]quinolines starting from 2-aryl-2H-indazoles with sulfoxonium ylides via rhodium(III)-catalyzed C-H activation and cyclization reaction has been described. This transformation features high efficiency, tolerates various functional groups, avoids external oxidant and produces dimethyl sulfoxide (DMSO) and H2O as the sole by-products. In addition, the scale-up reaction demonstrated the practicability of this protocol in industry.

Automated summary

An efficient synthesis of 6-arylindazolo[2,3-alpha]quinolines from 2-aryl-2H-indazoles using sulfoxonium ylides and rhodium(III)-catalyzed C-H activation and cyclization reaction is described. The transformation is highly efficient, tolerant to various functional groups, and does not require an external oxidant, resulting in dimethyl sulfoxide (DMSO) and H2O as the only by-products. Furthermore, the scalability of the reaction demonstrates its practicality in industry.