Organocatalytic Asymmetric Michael Addition of 5H-Oxazol-4-ones to Nitroolefins

The first organocatalytic asymmetric Michael addition of 5H-oxazol-4-ones to nitroolefins has been developed. In the presence of easily prepared L-tert-leucine-derived tertiary amine/thiourea catalyst, the Michael addition of 5H-oxazol-4-ones to nitroolefins proceeded in an excellent diastereo- and enantioselective manner (up to 99% ee and >19:1 dr). The Michael adducts obtained are valuable precursors for the synthesis of chiral α-alkyl-α-hydroxy carboxylic acid derivatives, which represent a series of versatile building blocks in many biologically active compounds.