Novel Chiral Bifunctional L-Thiazoline-Thiourea Derivatives: Design and Application in Enantioselective Michael Reactions

Several novel chiral bifunctional L-thiazoline-thiourea derivatives were easily synthesized from commercially available L-cysteine in high yield. These catalysts were subsequently applied to the enantioselective Michael addition of acetylacetone to β-nitrostyrenes. The products with S configuration were obtained in 98% enantiomeric excess (ee) when the L-thiazoline-thiourea derivatives were used. A plausible transition state model is proposed to explain the observed enantioselectivities. Chirality 27:979-988, 2015.