Highly Regio- and Stereoselective Synthesis of alpha-(N-Alkyl-N-p-toluenesulfonyl)-beta-Bromo-Ketones via Ni(OAc)(2)-Catalyzed Aminobromination of Chalcones

The combinations of N-methyl-p-toluenesulfonamide/NBS and N-ethyl-p-toluenesulfonamide/NBS were found to be good nitrogen/halogen resources for the aminohalogenation of α,β-unsaturated ketones in the presence of Ni(OAc)₂ as the catalyst for the synthesis of vicinal haloamino ketone derivatives. The introduction of N-alkyl groups to the nitrogen resources resulted in excellent regio- and stereoselectivity for both electron-donating and electron-withdrawing group-attached unsaturated ketone substrates. The structure of the resulting products has been unambiguously confirmed by X-ray crystal structure analysis.