Abstract: A novel chiral salen ligand was synthesized through the reaction of1,2:5,6-di-O-isopropylidene-3-O-methylene-[5-(3-tert-butyl-2-hydroxybenzaldehyde)]-α-D-glucofuranose with (1S,2S)-(-)-1,2-diphenylethylenediamine. The sugar-based chiral salen-Mn(Ⅲ) complex was prepared from this ligand. The ligand and complex were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and elemental analysis. The complex was then used as a catalyst for the asymmetric epoxidation of alkenes using NaClO and m-chloroperoxybenzoic acid as the oxidants. The results showed that the chiral sugar moiety that was incorporated into C5(5′) of the ligand had certain effect on enantioselectivity. Furthermore, the recycle ability of the catalyst was studied in the epoxidation of styrene with m-chloroperoxybenzoic acid as terminal oxidant in the presence of the ionic liquid [bmim]PF6. The enantiomeric excess of the epoxides was still 51% even after the catalyst was used three times.

Key words: asymmetric epoxidation, salen-Mn(Ⅲ) complex, glucose derivative, diphenylethylenediamine, ionic liquid