Asymmetric synthesis of epoxides from aromatic aldehydes and benzyl halides catalyzed by C-2 symmetric optically active sulfides having a binaphthyl skeleton

Reactions of aromatic aldehydes with benzyl bromide or iodide in the presence of a catalytic amount (10 mol%) of a C-2 symmetric sulfide having a binaphthyl skeleton afford the corresponding trans-stilbene oxides in moderate to good yields with moderate enantioselectivities (up to 55% enantiomeric excess). The addition of tetra-n-butylammonium iodide to the catalytic reaction system much improves the yield of the epoxides. (C) 2002 Wiley Periodicals, Inc.