Asymmetricepoxidation reaction of α,β-unsaturated carbonyl compounds with alkylperoxide was catalyzed by an external chiral tridentate aminodiether–lithium peroxide giving epoxides with good enantiomeric excess. Slow addition of alkylhydroperoxide was beneficial for a catalytic asymmetric reaction. Lone pair electron-differentiating coordination of a carbonyl oxygen to lithium is another critical