New catalytic system for aminohalogenation of β-methyl-β- nitrostyrenes to give opposite regiochemistry

A new combination of catalyst and co-additive has been found for aminohalogenation reaction of β-methyl-β-nitrostyrenes with N,N-dichloro-p-tolunesulfonamide (4-TsNCl₂). The reaction was achieved by using MnSO₄ as the catalyst together with tolunesulfonamide to give vicinal haloamino nitroalkanes with opposite regiochemistry to that generated from other electron-deficient olefins observed previously. The reaction proceeded smoothly at room temperature under nitrogen atmosphere to give useful to good yields and excellent regio and stereoselectivity. A mechanism involving the formation of chloronium intermediate was proposed to explain the resulting regio and stereochemistry.