Reactivity and Selectivity in the Wittig Reaction: A Computational Study.
The salt-free Wittig reaction of non-, semi-, and stabilized ylides has been investigated on realistic systems using density functional theory (DFT) calculations, including continuum solvation. Our results provide unequivocal support for the generally accepted mechanism and are in very good agreemen...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 7; pp. 2394 - 2410 |
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| Autores principales: | , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
2/22/2006
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| Materias: | |
| 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=20250856&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 20250856 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: 2/22/2006 vid: 128 iid: 7 pid: 997 pub: American Chemical Society artinfo: ui: 20250856 10.1021/ja056650q ppf: 2394 ppct: 16 formats: tig: atl: Reactivity and Selectivity in the Wittig Reaction: A Computational Study. aug: au: Robiette, Raphaël Richardson, Jeffery Aggarwal, Varinder K. Harvey, Jeremy N. affil: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K. su: Wittig reaction Density functionals Feasibility studies Nonmetals Chemical reactions Solution (Chemistry) sug: subj: Wittig reaction Density functionals Feasibility studies Nonmetals Chemical reactions Solution (Chemistry) ab: The salt-free Wittig reaction of non-, semi-, and stabilized ylides has been investigated on realistic systems using density functional theory (DFT) calculations, including continuum solvation. Our results provide unequivocal support for the generally accepted mechanism and are in very good agreement with experimental selectivities. This study shows that EIZ selectivity of non- and semi-stabilized ylides cannot be fully understood without considering the energy of the elimination TS. The influence of ylide stabilization and the nature of phosphorus substituents on reversibility of oxaphosphetane formation is clarified. Unexpectedly, the puckering ability of addition TSs is shown not to depend on ylide stabilization, but the geometry of the TS is decided by an interplay of 1,2; 1,3; and C-HߪO interactions in the case of non- and semi-stabilized ylides, whereas a dipole-dipole interaction governs the addition TS structures for stabilized ylides. The well-known influence of ylide stabilization on selectivity of PPh derivatives is explained as follows: in non- and semi-stabilized ylides reactions, cis and trans addition TSs have, respectively, puckered and planar geometries, and selectivity is governed by an interplay of 1,2 and 1,3 interactions. For stabilized ylides, the high E selectivity is due to a strong dipole-dipole interaction at the addition TS. The influence of the nature of phosphorus substituents on selectivity is also detailed, the different behavior of (MeO)PCHCOMe ylides being explained by their lower dipole. This novel picture of the factors determining TS structures and selectivity provides a sound basis for the design of new ylides. 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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