Practical and regioselective brominations of aromatic compounds using tetrabutylammonium peroxydisulfate

Direct bromination of wide range of aromatic compounds substituted with electron donating groups such as methoxy, hydroxy, or amino groups have been achieved with high regioselectivity by the reaction with Br₂ in the presence of tetrabutylammonium peroxydisulfate 1 under mild conditions in acetonitrile in excellent yields. The use of lithium bromide as a bromination reagent afforded high yields of monobromo compounds with complete regioselectivity under neutral and mild reaction conditions in acetonitrile.