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

The regio‐ and stereoselective aminobromination of α,β‐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 α,β‐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.