An Efficient Synthesis of 1-Substituted 5-Bromo-1H-tetrazoles

1-Substituted 1H-tetrazole-5-thiols were efficiently converted into the corresponding 1-substituted 5-bromo-1H-tetrazoles by treatment with zinc(II) bromide and 50% hydrogen peroxide or 36% peracetic acid at 70–80 °C. In most cases, the 5-bromotetrazole products could be isolated simply by dilution of the reaction mixture with water followed by filtration and washing of the precipitated product. Column chromatography was needed only in the case of one tetrazole that was additionally brominated on its side chain under the reaction conditions.