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- Publisher Website: 10.1002/chem.200700145
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- PMID: 17508383
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Article: On the mechanism and stereochemistry of chiral lithium-carbenoid-promoted cyclopropanation reactions
Title | On the mechanism and stereochemistry of chiral lithium-carbenoid-promoted cyclopropanation reactions |
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Authors | |
Keywords | Carbenoids Cyclopropanation Density functional calculations Reaction mechanisms Stereochemistry |
Issue Date | 2007 |
Publisher | Wiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry |
Citation | Chemistry - A European Journal, 2007, v. 13 n. 23, p. 6724-6731 How to Cite? |
Abstract | An investigation into the mechanism and stereochemistry of chiral lithium-carbenoid-promoted cyclopropanation reactions by using density functional theory (DFT) methods is reported. Previous work suggested that this type of cyclopropanation reaction may proceed by competition between a methylene-transfer mechanism and a carbometalation mechanism. In this paper, it is demonstrated that the intramolecular cyclopropanation reactions promoted by chiral carbenoids 1 and 2 proceed by the methylene-transfer mechanism. The carbometalation mechanism was found to have a much higher reaction barrier and does not appear to compete with the methylenetransfer mechanism. The Lewis base group does not enhance the carbometalation pathway enough to compete with the methylene-transfer pathway. The present computational results are consistent with experimental observations for these cyclopropanation reactions. The factors governing the stereochemistry of the intramolecular cyclopropanation reaction by the methylene-transfer mechanism were examined to help elucidate the origin of the stereoselectivity observed in experiments. Both the directing group and the configuration at the C 1 centre were found to play a key role in the stereochemistry. Carbenoid 1 has a chiral C 1 centre of R configuration. The Lewis base group directs the cyclization of carbenoid 1 to form a single product. In contrast, the Lewis base group cannot direct the cyclization of carbenoid 2 to furnish a stereoselective product due to the S configuration of the chiral C 1 centre in carbenoid 2. This relationship of the stereochemistry to the chiral character of the carbenoid has implications for the design of new efficient carbenoid reagents for stereoselective cyclopropanation. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
Persistent Identifier | http://hdl.handle.net/10722/168133 |
ISSN | 2023 Impact Factor: 3.9 2023 SCImago Journal Rankings: 1.058 |
ISI Accession Number ID | |
References |
DC Field | Value | Language |
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dc.contributor.author | Ke, Z | en_US |
dc.contributor.author | Zhou, Y | en_US |
dc.contributor.author | Gao, H | en_US |
dc.contributor.author | Zhao, C | en_US |
dc.contributor.author | Phillips, DL | en_US |
dc.date.accessioned | 2012-10-08T03:15:29Z | - |
dc.date.available | 2012-10-08T03:15:29Z | - |
dc.date.issued | 2007 | en_US |
dc.identifier.citation | Chemistry - A European Journal, 2007, v. 13 n. 23, p. 6724-6731 | en_US |
dc.identifier.issn | 0947-6539 | en_US |
dc.identifier.uri | http://hdl.handle.net/10722/168133 | - |
dc.description.abstract | An investigation into the mechanism and stereochemistry of chiral lithium-carbenoid-promoted cyclopropanation reactions by using density functional theory (DFT) methods is reported. Previous work suggested that this type of cyclopropanation reaction may proceed by competition between a methylene-transfer mechanism and a carbometalation mechanism. In this paper, it is demonstrated that the intramolecular cyclopropanation reactions promoted by chiral carbenoids 1 and 2 proceed by the methylene-transfer mechanism. The carbometalation mechanism was found to have a much higher reaction barrier and does not appear to compete with the methylenetransfer mechanism. The Lewis base group does not enhance the carbometalation pathway enough to compete with the methylene-transfer pathway. The present computational results are consistent with experimental observations for these cyclopropanation reactions. The factors governing the stereochemistry of the intramolecular cyclopropanation reaction by the methylene-transfer mechanism were examined to help elucidate the origin of the stereoselectivity observed in experiments. Both the directing group and the configuration at the C 1 centre were found to play a key role in the stereochemistry. Carbenoid 1 has a chiral C 1 centre of R configuration. The Lewis base group directs the cyclization of carbenoid 1 to form a single product. In contrast, the Lewis base group cannot direct the cyclization of carbenoid 2 to furnish a stereoselective product due to the S configuration of the chiral C 1 centre in carbenoid 2. This relationship of the stereochemistry to the chiral character of the carbenoid has implications for the design of new efficient carbenoid reagents for stereoselective cyclopropanation. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. | en_US |
dc.language | eng | en_US |
dc.publisher | Wiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry | en_US |
dc.relation.ispartof | Chemistry - A European Journal | en_US |
dc.subject | Carbenoids | - |
dc.subject | Cyclopropanation | - |
dc.subject | Density functional calculations | - |
dc.subject | Reaction mechanisms | - |
dc.subject | Stereochemistry | - |
dc.subject.mesh | Cyclopropanes - Chemistry | en_US |
dc.subject.mesh | Hydrocarbons - Chemistry | en_US |
dc.subject.mesh | Lithium - Chemistry | en_US |
dc.subject.mesh | Methane - Analogs & Derivatives - Chemistry | en_US |
dc.subject.mesh | Molecular Conformation | en_US |
dc.subject.mesh | Thermodynamics | en_US |
dc.title | On the mechanism and stereochemistry of chiral lithium-carbenoid-promoted cyclopropanation reactions | en_US |
dc.type | Article | en_US |
dc.identifier.email | Phillips, DL:phillips@hku.hk | en_US |
dc.identifier.authority | Phillips, DL=rp00770 | en_US |
dc.description.nature | link_to_subscribed_fulltext | en_US |
dc.identifier.doi | 10.1002/chem.200700145 | en_US |
dc.identifier.pmid | 17508383 | - |
dc.identifier.scopus | eid_2-s2.0-34547773279 | en_US |
dc.relation.references | http://www.scopus.com/mlt/select.url?eid=2-s2.0-34547773279&selection=ref&src=s&origin=recordpage | en_US |
dc.identifier.volume | 13 | en_US |
dc.identifier.issue | 23 | en_US |
dc.identifier.spage | 6724 | en_US |
dc.identifier.epage | 6731 | en_US |
dc.identifier.isi | WOS:000248710700022 | - |
dc.publisher.place | Germany | en_US |
dc.identifier.scopusauthorid | Ke, Z=14048262500 | en_US |
dc.identifier.scopusauthorid | Zhou, Y=16835391600 | en_US |
dc.identifier.scopusauthorid | Gao, H=36666205500 | en_US |
dc.identifier.scopusauthorid | Zhao, C=7403563836 | en_US |
dc.identifier.scopusauthorid | Phillips, DL=7404519365 | en_US |
dc.identifier.issnl | 0947-6539 | - |