Synthesis of 3‐(2‐Hydroxyaryl)indazole Derivatives through Radical O‐Arylation and [3,3]‐Rearrangement from N‐Hydroxyindazoles and Diaryliodonium Salts.

A variety of functionalized 3‐(2‐hydroxyaryl)indazoles and N‐(tetrahydrofuran‐2‐yl)‐3‐(2‐hydroxyaryl)indazoles were prepared in moderate to good yields through a transition metal‐free radical O‐arylation and sequential [3,3]‐rearrangement cascade strategy from N‐hydroxyindazoles and diaryliodonium salts. The equivalents of diaryliodonium salts controlled the formation of the product structures. Mechanistic studies revealed that the O‐arylation and N−O bond cleavage via [3,3]‐rearrangement involved an intermolecular radical process. The reaction tolerated various sensitive functional groups, such as halides, ester, and aldehyde groups. [ABSTRACT FROM AUTHOR]