Switching the Enantioselectivities in Michael Addition of Pyrazolin‐5‐Ones to Nitroolefins by Benzoylthiourea Organocatalysts

A series ofnovel cinchonaalkaloid derived benzoylthiourea organocatalysts weresynthesized and applied as hydrogen bonding organocatalysts in the enantioselective Michael addition of pyrazolin-5-ones to nitroolefins. These organocatalysts promoted the Michael additions smoothly and gave the desired R or S enantiomers of the products flexibly in high yields with excellent enantioselectivities (up to 92 %ee and 89 %eerespectively) by the proper choice of organocatalysts.