A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide

A convenient, rapid H2SO4-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H2SO4 using N-chlorosuccinimide and N-iodosuccinimide, respectively.