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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.

( S )-6,6′-Dibromo-BINOL and ( S )-6,6′-diphenyl-BINOL have been developed as efficient chiral ligands applicable to lanthanoid catalyzed asymmetric epoxidation of α,β-unsaturated ketones in the presence of cumene hydroperoxide. Excellent chemical yield and enantioselectivity have been achieved for several epoxides at room temperature by using 5 mol% of La( O - i -Pr) 3 -( S )-6,6′-dibromo-BINOL and Gd( O - i -Pr) 3 -( S )-6,6′-diphenyl-BINOL, respectively. Up to 95% ee was obtained for epoxychalcone with Gd( O - i -Pr) 3 -( S )-6,6-diphenyl-BINOL catalyst at room temperature. A plausible catalyst structure as well as the catalytic cycle has also been suggested.