Catalytic oxidative bromination is performed by using a commercially available inexpensive vanadium catalyst in the presence of a bromide salt and a Brønsted acid or a Lewis acid under molecular oxygen. Similarly, the combination of Bu4NI and AlCl3 in the presence of a vanadium catalyst under molecular oxygen induces the catalytic chlorination reaction. The vanadium-catalyzed oxidation system can be applied to the catalytic oxidative aromatization of 2-cyclohexenones to afford the corresponding phenol derivatives. The catalytic direct amination of allyl alcohols with both aromatic and aliphatic amines is achieved by utilizing an oxovanadium(v) catalyst. Furthermore, oxovanadium(v) compounds catalyze direct hydrazination of allyl alcohol and deoxygenative homocoupling reaction of alcohols depending on hydrazine derivatives.