Asymmetric epoxidation of unfunctionalized alkenes catalyzed by sugar moiety-modified chiral salen-Mn(III) complexes

Carbohydr Res. 2009 Jan 5;344(1):61-6. doi: 10.1016/j.carres.2008.10.005. Epub 2008 Oct 14.

Abstract

Several chiral Schiff-base ligands with sugar moieties at C-3 (3') or C-5 (5') of salicylaldehyde were synthesized from reaction of salicylaldehyde derivatives with diamine. These ligands coordinated with Mn(III) to afford the corresponding chiral salen-Mn(III) complexes characterized by FT-IR, MS, and elementary analysis. These complexes were used as catalysts for the asymmetric epoxidation of unfunctionalized alkenes. Only weak enantioselectivity is induced by the chiral sugar moieties at C-3 (3') or C-5 (5') in the case of absence of chirality in the diimine bridge moiety. It was also shown that the sugars at C-5 (5') having the same rotation direction of polarized light as the diimine bridge in the catalyst could enhance the chiral induction in the asymmetric epoxidation, but the sugars with the opposite rotation direction would reduce the chiral induction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkenes / chemistry*
  • Carbohydrates / chemistry*
  • Catalysis
  • Epoxy Compounds / chemical synthesis*
  • Epoxy Compounds / chemistry
  • Ethylenediamines / chemistry*
  • Molecular Structure
  • Organometallic Compounds / chemistry*
  • Stereoisomerism

Substances

  • Alkenes
  • Carbohydrates
  • Epoxy Compounds
  • Ethylenediamines
  • Organometallic Compounds
  • N,N'-bis(salicylideneamino)ethane-manganese(II)