Mechanistic basis for high reactivity of (salen)Co-OTs in the hydrolytic kinetic resolution of terminal epoxides

J Org Chem. 2012 Mar 2;77(5):2486-95. doi: 10.1021/jo300181f. Epub 2012 Feb 8.


The (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides is a bimetallic process with a rate controlled by partitioning between a nucleophilic (salen)Co-OH catalyst and a Lewis acidic (salen)Co-X catalyst. The commonly used (salen)Co-OAc and (salen)Co-Cl precatalysts undergo complete and irreversible counterion addition to epoxide during the course of the epoxide hydrolysis reaction, resulting in quantitative formation of weakly Lewis acidic (salen)Co-OH and severely diminished reaction rates in the late stages of HKR reactions. In contrast, (salen)Co-OTs maintains high reactivity over the entire course of HKR reactions. We describe here an investigation of catalyst partitioning with different (salen)Co-X precatalysts and demonstrate that counterion addition to epoxide is reversible in the case of the (salen)Co-OTs. This reversible counterion addition results in stable partitioning between nucleophilic and Lewis acidic catalyst species, allowing highly efficient catalysis throughout the course of the HKR reaction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cobalt / chemistry*
  • Epoxy Compounds / chemistry*
  • Ethylenediamines / chemistry*
  • Hydrolysis
  • Kinetics
  • Molecular Structure
  • Organometallic Compounds / chemistry*


  • Epoxy Compounds
  • Ethylenediamines
  • Organometallic Compounds
  • Cobalt
  • disalicylaldehyde ethylenediamine