Catalysis Letters, Vol.90, No.1-2, 91-94, 2003
Catalytic asymmetric epoxidation of unfunctionalized olefins by supported Cu(II)-amino acid complexes
Polymer-supported Cu(II) complexes with L-phenyl alanine and L-valine were used as chiral catalysts for asymmetric epoxidation of nonfunctionalized straight-chain terminal olefins viz. 1-octene, 1-hexene, 2-methyl-1-pentene and 4-methyl-1-pentene using m-chloroperbenzoic acid (m-CPBA) as oxidant giving high conversions and selectivity. Enantiomeric yields, though moderate, are comparable with the best-reported ees using homogeneous catalysts. All catalysts displayed good recycling efficiency. Variations in percent ee have been discussed on the basis of the structural geometry of the supported catalysts and the trajectory of the olefin approach to the active oxo-intermediate.
Keywords:Cu-amino acid complexes;polymer-supported catalyst;asymmetric epoxidation;1-octene;recycling