Asymmetric epoxidation of olefins with oxone was first catalyzed by chiral iminium salts generated in situ from chiral amines and aldehydes. With 2S,5S-2,5-dicyclohexylaminocarbonylpyrolidine and t-butylacetaldehyde, trans-stilbene were epoxdized in 80% conversion, 93% yield and 65% e.e. at 0 ℃.
