Article: Alkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligands

File Download Links for fulltext
(May Require Subscription)
Supplementary
  • Basic View
  • Metadata View
  • XML View
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
2011 Impact Factor: 3.838
2011 SCImago Journal Rankings: 0.254
DOIhttp://dx.doi.org/10.1039/b606757c
ISI Accession Number IDWOS:000241149100011
ReferencesReferences in Scopus
DC Field
Value
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
2011 Impact Factor: 3.838
2011 SCImago Journal Rankings: 0.254
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
Author Affiliations
  1. Institute of Molecular Technology for Drug Discovery and Synthesis, Hong Kong
  2. Hong Kong Polytechnic University