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Article: Alkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligands
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TitleAlkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligands
 
AuthorsLai, TS2
Chan, FY2
So, PK2
Ma, DL2
Wong, KY2
Che, CM1
 
Issue Date2006
 
PublisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/dalton
 
CitationDalton Transactions, 2006 n. 40, p. 4845-4851 [How to Cite?]
DOI: http://dx.doi.org/10.1039/b606757c
 
AbstractWith the iron(iii) complex of the Halterman iron porphyrin [P*Fe(Cl)] and ethyl diazoacetate (EDA) as catalyst and carbene source, respectively, styrene-type substrates were converted to cyclopropyl esters with high trans/cis ratio (not less than 12) and high enantioselectivity for the trans-isomers (74-86% ee). The isomeric distribution of the cyclopropyl esters so obtained is akin to that obtained from the previously reported Ru(ii) counterpart [P*Ru(CO)]. A linear Hammett correlation log(k X/k H) = σ +ρ was observed with ρ = -0.57 suggesting the involvement of an electrophilic cyclopropanating species derived from the iron(ii) center as the reactive intermediate in the catalytic cycle. This is further supported by a dramatic decrease in the enantioselectivity and trans/cis ratio observed in an experiment of styrene cyclopropanation when the reaction mixture was deliberately exposed to air. Axial ligand effects on the selectivities was also investigated. Substantial improvement in trans/cis ratios could be achieved by addition of organic bases such as pyridine (py) and 1-methylimidazole (MeIm) to the catalytic reaction. The existence of axially ligated iron carbene moieties, [P*Fe(CHCO 2Et)(py)] and [P*Fe(CHCO 2Et)(MeIm)], was established by electrospray mass spectrometry. Study of secondary kinetic isotope effect indicated that a more product-like transition state was generated by addition of MeIm. © The Royal Society of Chemistry 2006.
 
ISSN1477-9226
2012 Impact Factor: 3.806
2012 SCImago Journal Rankings: 1.331
 
DOIhttp://dx.doi.org/10.1039/b606757c
 
ISI Accession Number IDWOS:000241149100011
 
ReferencesReferences in Scopus
 
DC FieldValue
dc.contributor.authorLai, TS
 
dc.contributor.authorChan, FY
 
dc.contributor.authorSo, PK
 
dc.contributor.authorMa, DL
 
dc.contributor.authorWong, KY
 
dc.contributor.authorChe, CM
 
dc.date.accessioned2010-09-06T06:19:24Z
 
dc.date.available2010-09-06T06:19:24Z
 
dc.date.issued2006
 
dc.description.abstractWith the iron(iii) complex of the Halterman iron porphyrin [P*Fe(Cl)] and ethyl diazoacetate (EDA) as catalyst and carbene source, respectively, styrene-type substrates were converted to cyclopropyl esters with high trans/cis ratio (not less than 12) and high enantioselectivity for the trans-isomers (74-86% ee). The isomeric distribution of the cyclopropyl esters so obtained is akin to that obtained from the previously reported Ru(ii) counterpart [P*Ru(CO)]. A linear Hammett correlation log(k X/k H) = σ +ρ was observed with ρ = -0.57 suggesting the involvement of an electrophilic cyclopropanating species derived from the iron(ii) center as the reactive intermediate in the catalytic cycle. This is further supported by a dramatic decrease in the enantioselectivity and trans/cis ratio observed in an experiment of styrene cyclopropanation when the reaction mixture was deliberately exposed to air. Axial ligand effects on the selectivities was also investigated. Substantial improvement in trans/cis ratios could be achieved by addition of organic bases such as pyridine (py) and 1-methylimidazole (MeIm) to the catalytic reaction. The existence of axially ligated iron carbene moieties, [P*Fe(CHCO 2Et)(py)] and [P*Fe(CHCO 2Et)(MeIm)], was established by electrospray mass spectrometry. Study of secondary kinetic isotope effect indicated that a more product-like transition state was generated by addition of MeIm. © The Royal Society of Chemistry 2006.
 
dc.description.natureLink_to_subscribed_fulltext
 
dc.identifier.citationDalton Transactions, 2006 n. 40, p. 4845-4851 [How to Cite?]
DOI: http://dx.doi.org/10.1039/b606757c
 
dc.identifier.doihttp://dx.doi.org/10.1039/b606757c
 
dc.identifier.epage4851
 
dc.identifier.hkuros157082
 
dc.identifier.isiWOS:000241149100011
 
dc.identifier.issn1477-9226
2012 Impact Factor: 3.806
2012 SCImago Journal Rankings: 1.331
 
dc.identifier.issue40
 
dc.identifier.openurl
 
dc.identifier.pmid17033710
 
dc.identifier.scopuseid_2-s2.0-33749849466
 
dc.identifier.spage4845
 
dc.identifier.urihttp://hdl.handle.net/10722/70066
 
dc.languageeng
 
dc.publisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/dalton
 
dc.publisher.placeUnited Kingdom
 
dc.relation.ispartofDalton Transactions
 
dc.relation.referencesReferences in Scopus
 
dc.titleAlkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligands
 
dc.typeArticle
 
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<contributor.author>Wong, KY</contributor.author>
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<description.abstract>With the iron(iii) complex of the Halterman iron porphyrin [P*Fe(Cl)] and ethyl diazoacetate (EDA) as catalyst and carbene source, respectively, styrene-type substrates were converted to cyclopropyl esters with high trans/cis ratio (not less than 12) and high enantioselectivity for the trans-isomers (74-86% ee). The isomeric distribution of the cyclopropyl esters so obtained is akin to that obtained from the previously reported Ru(ii) counterpart [P*Ru(CO)]. A linear Hammett correlation log(k X/k H) = &#963; +&#961; was observed with &#961; = -0.57 suggesting the involvement of an electrophilic cyclopropanating species derived from the iron(ii) center as the reactive intermediate in the catalytic cycle. This is further supported by a dramatic decrease in the enantioselectivity and trans/cis ratio observed in an experiment of styrene cyclopropanation when the reaction mixture was deliberately exposed to air. Axial ligand effects on the selectivities was also investigated. Substantial improvement in trans/cis ratios could be achieved by addition of organic bases such as pyridine (py) and 1-methylimidazole (MeIm) to the catalytic reaction. The existence of axially ligated iron carbene moieties, [P*Fe(CHCO 2Et)(py)] and [P*Fe(CHCO 2Et)(MeIm)], was established by electrospray mass spectrometry. Study of secondary kinetic isotope effect indicated that a more product-like transition state was generated by addition of MeIm. &#169; The Royal Society of Chemistry 2006.</description.abstract>
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Author Affiliations
  1. Institute of Molecular Technology for Drug Discovery and Synthesis, Hong Kong
  2. Hong Kong Polytechnic University