Enhanced cooperativity through design: Pendant CoIII-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion)

Christopher S. Gill, Krishnan Venkatasubbaiah, Nam T.S. Phan, Marcus Weck, Christopher W. Jones

Research output: Contribution to journalArticle

Abstract

The CoIII-salen-catalyzed (salen = N,N'-bis(salicylidene) ethylenediamine dianion) hydrolytic kinetic resolution (HKR) of racemic epoxides has emerged as a highly attractive and efficient method of synthesizing chiral C3 building blocks for intermediates in larger, more complex molecules. HKR reaction rates have displayed a second order dependency on the concentration of active sites, and thus researchers have proposed a bimetallic transition state for the HKR mechanism. Here we report the utilization of pendant CoIII-salen catalysts on silica supported polymer brushes as a catalyst for the HKR of epichlorohydrin. The novel polymer brush architecture provided a unique framework for promoting site-site interactions as required in the proposed bimetallic transition state of the HKR mechanism. Furthermore, the polymer brushes mimic the environment of soluble polymer-based catalysts, whereas the silica support permitted facile recovery and reuse of the catalyst. The polymer brush catalyst displayed increased activities over the soluble Jacobsen Co-salen catalyst and was observed to retain its high enantioselectivities (> 99%) after each of five reactions despite decreasing activities. Analysis indicated decomposition of the salen ligand as an underlying cause of catalyst deactivation.

Original languageEnglish (US)
Pages (from-to)7306-7313
Number of pages8
JournalChemistry - A European Journal
Volume14
Issue number24
DOIs
StatePublished - Aug 18 2008

Keywords

  • Asymmetric synthesis
  • Cobalt-salen
  • Heterogeneous catalysis
  • Kinetic resolution
  • Polymer brush

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

Fingerprint Dive into the research topics of 'Enhanced cooperativity through design: Pendant Co<sup>III</sup>-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion)'. Together they form a unique fingerprint.

Cite this