Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by chiral ytterbium complexes

Several derivatives of (S)-(−)-BINOL ligands with 6,6′-substitutents were synthesized and applied as chiral ligands in the Yb(O-i-Pr)3-catalyzed asymmetric epoxidation of α,β-unsaturated ketones. Superior results were obtained with 6,6′-diphenyl-BINOL, exemplified in the asymmetric epoxidation of (E)-1,3-diphenylprop-2-en-1-one in 91% yield and up to 97% ee.