Aluminium Powder-Catalyzed Regio- and Stereoselective Aminobromination of α,β-Unsaturated Carbonyl Compounds and Simple Olefins with thep-Toluenesulfonamide/N-Bromosuccinimide (TsNH₂-NBS) System

The regio- and stereoselective aminobromination of alpha,beta-unsaturated carbonyl compounds and simple olefins catalyzed by elementary aluminium powder has been established by using p-toluenesulfonamide (TsNH2) and N-bromosuccinimide (NBS) as the nitrogen/bromine sources. The reaction was convenient to carry out with a loading of 1 mol% catalyst at room temperature without inert gas protection. This method provides an easy approach to trans vicinal haloamino derivatives of alpha,beta-unsaturated carbonyl compounds and simple olefins in high yields (up to 99.8%) and in excellent regio- and stereoselectivities. The electron-rich and electron-deficient olefins show significant differences in activity to the aminobromination reaction and give the opposite regioselectivities. Two possible pathways involving separately a bromonium or an aziridinium intermediate have been proposed.