Rhodium-Catalyzed Directed C(sp²)–H Bond Addition of 2-Arylindazoles to <i>N</i>-Sulfonylformaldimines and Activated Aldehydes

Abstract

Rhodium-catalyzed directed C–H functionalization of 2-arylindazoles with N-sulfonylformaldimines has been developed to provide a variety of N-benzylarylsulfonamide derivatives with good to excellent yields. Different activated aldehydes like ethyl glyoxalate and 2,2,2-trifluoroacetaldehyde also efficiently underwent nucleophilic addition with 2-arylindazoles. These selective transformations occur through the control of C3 nucleophilicity of indazole moiety. Mechanistic studies suggest that C–H activation step may be a rate-limiting step.

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