Abstract: A novel chiral oligomeric cyclic salen ligand was synthesized by the reaction of a novel dialdehyde with (1R,2R)-1,2-diaminocyclohexane. From this ligand, the chiral oligomeric cyclic salen-Mn(Ⅲ) complex was prepared. The ligand and complex were characterized by nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, UV-Vis spectroscopy, gel permeation chromatography, and elemental analysis. The complex was used as a catalyst for the asymmetric epoxidation of olefin using NaClO and m-chloroperoxybenzoic acid as the oxidants, respectively. In the asymmetric epoxidation of cis-β-methylstyrene, the selectivity and enantiometric excess for the epoxides reached 96% and 78%, respectively. The recyclability of the catalyst was also studied.

Key words: asymmetric epoxidation, non-functional olefin, oligomeric salen-Mn(Ⅲ) complex, electronic effect, axial ligand