Metal-free electrochemical regioselective aromatic C–H bromination of N,N-disubstituted anilines using propargyl bromide as the unprecedented bromine source

Source of a functional group is always an important factor in the chemical synthesis. Herein a new method for the highly regioselective monobromination of N,N-disubstituted anilines has been disclosed using propargyl bromide as the unconventional bromine source under electrochemical condition. Unlike other bromine sources, neither it requires any polarization nor any activator. The reaction smoothly proceeds at room temperature without using any metal catalyst or bromide salt. For unsubstituted anilines regioselective para-bromination was observed whereas both meta- and para-substituted anilines undergo predominant ortho-bromination leading to the corresponding N,N-disubstituted bromoanilines in good yields. Plausible mechanism has been depicted with supporting B3LYP/6-31G DFT calculations to explain the relative energy driven process.