Metal-free regioselective mono- and poly-halogenation of 2-substituted indazoles

An unprecedented metal-free regioselective halogenation of 2H-indazoles has been revealed, which not only realized the highly selective synthesis of mono-halogenated products, but also completed poly-halogenations by fine tuning the reaction conditions. Various mono-/poly-/hetero-halogenated indazoles were obtained in moderate to excellent yields. Notably, this approach features environmentally friendly solvents, mild reaction conditions, simple execution and short reaction time.

Automated summary

We report an unprecedented metal-free regioselective halogenation of 2H-indazoles, which achieved highly selective synthesis of mono-halogenated products and completed poly-halogenations by fine tuning the reaction conditions. Various mono-/poly-/hetero-halogenated indazoles were obtained in moderate to excellent yields. Importantly, this approach offers environmentally friendly solvents, mild reaction conditions, simple execution, and short reaction time.