Regio- and stereoselective copper-catalyzed synthesis of vicinal haloamino ketones from α,β-unsaturated ketones

The regio- and stereoselective aminochlorination of α,β- unsaturated ketones has been developed. The reaction was conducted with N,N-dichloro-p-toluenesulfonamide (4-TsNCl₂) as the nitrogen/halogen source and CuOTf as the catalyst, at 0 °C to room temperature. This method provides an easy access to vicinal haloamino ketones, with excellent regioselectivity and up to quantitative yields. Both aromatic and aliphatic enones react well with 4-TsNCl₂ under the present system, but give opposite regioselectivity.