Metal-free selective mono-halodecarboxylation of heteroarenes under mild conditions

The halodecarboxylation of heteroarene carboxylic acids by treatment with N-bromosuccinimide or N-chlorosuccinimide was performed. This procedure provides a convenient route to synthetically useful mono-halogenated heteroarene intermediates such as halo-indoles, -aza-indoles, -indazoles and -aza-indazoles. The mild conditions employed and simple protocol provides an advantage over traditional halodecarboxylation procedures that require expensive and toxic metal catalysts, basic conditions, time-consuming intermediate isolation and elevated reaction temperatures.