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

TitleAlkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligands
Authors
Issue Date2006
PublisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/dalton
Citation
Dalton Transactions, 2006 n. 40, p. 4845-4851 How to Cite?
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.
Persistent Identifierhttp://hdl.handle.net/10722/70066
ISSN
2014 Impact Factor: 4.197
2014 SCImago Journal Rankings: 1.283
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLai, TSen_HK
dc.contributor.authorChan, FYen_HK
dc.contributor.authorSo, PKen_HK
dc.contributor.authorMa, DLen_HK
dc.contributor.authorWong, KYen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2010-09-06T06:19:24Z-
dc.date.available2010-09-06T06:19:24Z-
dc.date.issued2006en_HK
dc.identifier.citationDalton Transactions, 2006 n. 40, p. 4845-4851en_HK
dc.identifier.issn1477-9226en_HK
dc.identifier.urihttp://hdl.handle.net/10722/70066-
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.en_HK
dc.languageengen_HK
dc.publisherRoyal Society of Chemistry. The Journal's web site is located at http://www.rsc.org/daltonen_HK
dc.relation.ispartofDalton Transactionsen_HK
dc.titleAlkene cyclopropanation catalyzed by Halterman iron porphyrin: Participation of organic bases as axial ligandsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1477-9226&volume=&spage=4845&epage=4851&date=2006&atitle=Alkene+Cyclopropanation+Catalyzed+by+Halterman+Iron+Porphyrin:+Participation+of+Organic+Bases+as+Axial+Ligands+en_HK
dc.identifier.emailMa, DL:edmondma@hku.hken_HK
dc.identifier.emailChe, CM:cmche@hku.hken_HK
dc.identifier.authorityMa, DL=rp00760en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1039/b606757cen_HK
dc.identifier.pmid17033710-
dc.identifier.scopuseid_2-s2.0-33749849466en_HK
dc.identifier.hkuros157082en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-33749849466&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.issue40en_HK
dc.identifier.spage4845en_HK
dc.identifier.epage4851en_HK
dc.identifier.isiWOS:000241149100011-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLai, TS=7202203490en_HK
dc.identifier.scopusauthoridChan, FY=36719313500en_HK
dc.identifier.scopusauthoridSo, PK=14919747700en_HK
dc.identifier.scopusauthoridMa, DL=7402075538en_HK
dc.identifier.scopusauthoridWong, KY=7404760030en_HK
dc.identifier.scopusauthoridChe, CM=7102442791en_HK

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