Enantioselective Michael Addition of Pyrazolin-5-ones to β-CF3-β-Disubstituted Nitroalkenes Catalyzed by Squaramide Organocatalyst

Abstract

A highly enantioselective Michael addition of pyrazolin-5-ones with β-CF₃-β-disubstituted nitroalkenes catalyzed by bifunctional squaramide has been developed. Various chiral β-CF₃-β-5-hydroxy-pyrazolin-3-yl-disubstituted nitroalkane derivatives bearing all-carbon quaternary stereocenter were prepared in good yields (up to 88%) and excellent enantioselectivities (up to 97% ee).