Hydrazone ligated–vanadium(V) complex: catalytic oxidative bromination of organic substrates promoted by Brønsted acid or Lewis acid

Vanadium(V) complex was prepared by reaction of vanadium acetylacetonate with hydrazone ligand. The complex was characterized by IR, 1H NMR and UV-Visible spectroscopy. The structure of the complex was confirmed by single crystal X-ray crystallography. The complex shows biomimetic catalytic activity similar to that of haloperoxidases enzyme and brominate various organic substrates efficiently in presence of bromide salt, Lewis acid, or Brønsted acid. It was shown that using aluminium halide as a Lewis acid instead of a Brønsted acid produced a more workable approach for oxidative bromination reactions. In our current studies we observed that oxidative bromination reaction of ketones yielded only α-bromination products. It was discovered that AlBr3 functioned as a Lewis acid and a source of bromide to easily initiate the bromination reactions.