Catalytic diamination of alkenes using N,N-dibromo-p-toluenesulfonamide as electrophile and nitriles as nucleophiles

An efficient diamination reaction of alkenes has been developed for the synthesis of bromoalkyl-branched imidazolines by using CuI-PPh₃ as the catalyst and N,N-dibromo-p-toluenesulfonamide as the nitrogen/halogen sources. A good scope of alkene substrates, including α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins, was achieved for this reaction. Meanwhile, various nitriles were utilized as nucleophilic nitrogen sources. Modest to good yields and excellent regio- and stereoselectivity have been obtained. The stereochemistry was unambiguously confirmed by X-ray structural analysis. A new mild condition was found for the opening of resulting imidazolines by using SnCl₄ as the promoter.