Chiral Scandium Catalysts for Enantioselective Michael Reactions of β‐Ketoesters

A highly enantioselective Michael reaction of β‐ketoesters with α,β‐unsaturated ketones promoted by a chiral scandium catalyst has been developed. In the presence of Sc(OTf) 3 and ( S , S )‐6,6′‐bis(1‐hydroxy‐2,2′‐dimethylpropyl)‐2,2′‐bipyridine, the desired Michael reactions proceeded smoothly in dichloroethane at 40 °C to afford the corresponding adducts in good to high yields with excellent enantioselectivities in most cases. It was found in this reaction that a lower concentration of the reaction mixture was key to attaining high enantioselectivities.