Rapid and halide compatible synthesis of 2-N-substituted indazolone derivatives via photochemical cyclization in aqueous media

Indazolone derivatives exhibit a wide range of biological and pharmaceutical properties. We report a rapid and efficient approach to provide structurally diverse 2-N-substituted indazolones via photochemical cyclization in aqueous media at room temperature. This straightforward protocol is halide compatible for the synthesis of halogenated indazolones bearing a broad scope of substrates, which suggests a new avenue of great importance to medicinal chemistry.