Theoretical Investigation of Enolborane Addition to α-Heteroatom-Substituted Aldehydes. Relevance of the Cornforth and Polar Felkin-Anh Models for Asymmetric Induction.
The addition of enolborane nucleophiles to chiral α-heteroatom-substituted aldehydes (CHCH-(X)CHO, X = F, Cl, OMe, SMe, NMe, and PMe) was investigated using density functional theory by means of B3LYP/6-31G(d) calculations, with particular emphasis on determining the relevance of the polar Felkin-An...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 9; pp. 2920 - 2931 |
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| Autores principales: | , , |
| Formato: | Artículo |
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American Chemical Society
3/8/2006
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=20426315&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 20426315 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 3/8/2006 vid: 128 iid: 9 pid: 997 pub: American Chemical Society artinfo: ui: 20426315 10.1021/ja0555670 ppf: 2920 ppct: 11 formats: tig: atl: Theoretical Investigation of Enolborane Addition to α-Heteroatom-Substituted Aldehydes. Relevance of the Cornforth and Polar Felkin-Anh Models for Asymmetric Induction. aug: au: Cee, Victor J. Cramer, Christopher J. Evans, David A. affil: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455 su: Density functionals Aldehydes Asymmetric synthesis Chirality Functional analysis Organic compounds sug: subj: Density functionals Aldehydes Asymmetric synthesis Chirality Functional analysis Organic compounds ab: The addition of enolborane nucleophiles to chiral α-heteroatom-substituted aldehydes (CHCH-(X)CHO, X = F, Cl, OMe, SMe, NMe, and PMe) was investigated using density functional theory by means of B3LYP/6-31G(d) calculations, with particular emphasis on determining the relevance of the polar Felkin-Anh and Cornforth models for asymmetric induction in these reactions. The relative energy of the polar Felkin-Anh and Cornforth transition-state structures is found to depend on the nature of the α-heteroatom substituent, with electronegative substituents (F, OMe, CI) favoring Cornforth structures, while less electronegative substituents (PMe, SMe, NMe) favor polar Felkin-Anh structures. These transition-state preferences are correlated with the relative energy of the corresponding rotamer of the uncomplexed reactant aldehyde, indicating that the transition states are particularly sensitive to the conformation of the aldehyde. The proposed Nu ↵ σ* interaction that forms the basis of the polar Felkin-Anh model appears to be insignificant in reactions with enolborane nucleophiles. The calculated transition-state structures for the addition of E- and Z-enolborane nucleophiles to 2-methoxypropanal predict a diastereofacial selectivity that is in good agreement with the experimentally determined values. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
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