Asymmetric Conjugate Addition of Acetylacetone to Nitroolefins with Chiral Organocatalysts Derived from Both α‐Amino ­Acids and Carbohydrates

Abstract

AbstractBifunctional chiral tertiary amine thioureas derived from both α‐amino acids and carbohydrates were developed. These organocatalysts promoted the enantioselective conjugate addition of acetylacetone to various aromatic and aliphatic nitroolefins at room temperature in good yields (up to 93 %) and with good enantioselectivity (up to 90 % ee). Furthermore, an interesting matched–mismatched effect of two different chiral units in a chiral organocatalyst was disclosed. Both enantiomers of a product can be achieved in almost the same enantiomeric excess with the “matched” and “mismatched” chiral organocatalysts simply by changing the solvent from THF to toluene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)