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

Fingerprint

ethylenediamine
Epichlorohydrin
Brushes
Polymers
Catalysts
Kinetics
Silicon Dioxide
Silica
Catalyst deactivation
Enantioselectivity
Epoxy Compounds
Catalyst supports
Reaction rates
disalicylaldehyde ethylenediamine
Catalyst activity
Ligands

Keywords

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

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Enhanced cooperativity through design : Pendant CoIII-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion). / Gill, Christopher S.; Venkatasubbaiah, Krishnan; Phan, Nam T S; Weck, Marcus; Jones, Christopher W.

In: Chemistry - A European Journal, Vol. 14, No. 24, 18.08.2008, p. 7306-7313.

Research output: Contribution to journalArticle

@article{f1123cb9b1ea4063b4044b88ad00ab84,
title = "Enhanced cooperativity through design: Pendant CoIII-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion)",
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.",
keywords = "Asymmetric synthesis, Cobalt-salen, Heterogeneous catalysis, Kinetic resolution, Polymer brush",
author = "Gill, {Christopher S.} and Krishnan Venkatasubbaiah and Phan, {Nam T S} and Marcus Weck and Jones, {Christopher W.}",
year = "2008",
month = "8",
day = "18",
doi = "10.1002/chem.200800532",
language = "English (US)",
volume = "14",
pages = "7306--7313",
journal = "Chemistry - A European Journal",
issn = "0947-6539",
publisher = "Wiley-VCH Verlag",
number = "24",

}

TY - JOUR

T1 - Enhanced cooperativity through design

T2 - Pendant CoIII-salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion)

AU - Gill, Christopher S.

AU - Venkatasubbaiah, Krishnan

AU - Phan, Nam T S

AU - Weck, Marcus

AU - Jones, Christopher W.

PY - 2008/8/18

Y1 - 2008/8/18

N2 - 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.

AB - 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.

KW - Asymmetric synthesis

KW - Cobalt-salen

KW - Heterogeneous catalysis

KW - Kinetic resolution

KW - Polymer brush

UR - http://www.scopus.com/inward/record.url?scp=53849141862&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=53849141862&partnerID=8YFLogxK

U2 - 10.1002/chem.200800532

DO - 10.1002/chem.200800532

M3 - Article

VL - 14

SP - 7306

EP - 7313

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

SN - 0947-6539

IS - 24

ER -