Enantioselective Bromolactonization of Deactivated Olefinic Acids

A novel enantioselective bromolactonization of α,β-unsaturated ketones using bifunctional amino-urea catalysts has been developed. The scope of the reaction is evidenced by 23 examples of halolactones bearing various functionalities with up to 99% yield and 99:1 er. Unlike typical urea catalysts that require electron-deficient substituents to enhance the hydrogen bond strength, it is interesting to realize that electron-rich ureas are essential for high enantioselectivity in this case. Moreover, experimental data reveals that the halolactone compounds exhibit considerable anti-inflammatory effects on LPS-induced RAW 264.7 cells.