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

Bifunctional chiral tertiary amine thioureas derived from both alpha-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. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)