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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)