Sterically Hindered Free-Radicals .21. 1,2- and 1,4-Additions of Diphenylmethyl Radicals to Substituted Acrylonitriles
| dc.contributor.author | Zarkadis, A. K. | en |
| dc.contributor.author | Neumann, W. P. | en |
| dc.contributor.author | Dunnebacke, D. | en |
| dc.contributor.author | Penenory, A. | en |
| dc.contributor.author | Stapel, R. | en |
| dc.contributor.author | Stewen, U. | en |
| dc.date.accessioned | 2015-11-24T16:47:53Z | |
| dc.date.available | 2015-11-24T16:47:53Z | |
| dc.identifier.issn | 0009-2940 | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/9249 | |
| dc.rights | Default Licence | - |
| dc.subject | radical additions | en |
| dc.subject | acrylonitriles | en |
| dc.subject | diphenylmethyl radicals | en |
| dc.subject | steric effects | en |
| dc.subject | electron-spin-resonance | en |
| dc.subject | photoelectron-spectroscopy | en |
| dc.subject | addition-reactions | en |
| dc.subject | alkenes | en |
| dc.subject | olefins | en |
| dc.subject | methyl | en |
| dc.subject | ethyl | en |
| dc.title | Sterically Hindered Free-Radicals .21. 1,2- and 1,4-Additions of Diphenylmethyl Radicals to Substituted Acrylonitriles | en |
| heal.abstract | Additions of the substituted diphenylmethyl radicals Ar1Ar2CR 2 (R = CMe3, SiMe3, GeMe3, SnMe3, OSiMe3, CF3, CO2Me, CN) to various acrylonitriles CH2 = C(X)CN 3 (X = SMe, SiPr, StBu, OAc, OSiMe3, OSiEt3, OMe, OEt) lead to 1,2-5 or 1,4-adducts 6 (ketenimines), depending mainly on the steric hindrance by the substituents R and X. Bulky substituents like tBu in 2 and tBuS in the acrylonitrile favour the formation of the extended and nearly strainless ketenimine system 6 (1,4-adduct); smaller substituents like OSiMe3 (radical 2) and SMe, OAc, OSiMe3, OSiEt3, OMe, OEt (acrylonitrile) allow isolation of the sterically crowded 1,2-adducts. Substituents of intermediate bulkiness like CF3 (radical 2) and SiPr (acrylonitrile) give a mixture of 1,2-adducts (6cb,hb) and dimers 7 of the adduct radicals 4 (7cb,hb). The voluminous tBu group directly bound to the olefin (3j,k) prevents addition. The latter is generally reversible, and the various adducts 5, 6, or 7 dissociate to the adduct radicals 4 and/or fragment to the initial radicals 2 at temperatures which reflect the steric strains of the corresponding substituents R, X. The complete inertness, even toward the electron-rich olefin 3i, of the electrophilic alpha-carbonyl-substituted radicals 2q-s (R = CHO, COMe, COPh) in the above additions is discussed. Additions of the radicals 2a-c,f,i,n,o to the conjugated olefin 3n are described and are in accordance with the conclusion that steric effects predominate in adduct formation, whereas electronic effects are of distinct but minor importance. | en |
| heal.access | campus | - |
| heal.fullTextAvailability | TRUE | - |
| heal.identifier.primary | DOI 10.1002/cber.19931260518 | - |
| heal.identifier.secondary | <Go to ISI>://A1993LF23000017 | - |
| heal.identifier.secondary | http://onlinelibrary.wiley.com/store/10.1002/cber.19931260518/asset/19931260518_ftp.pdf?v=1&t=hmsuc0va&s=48a41570803706f315114055b2e01ff24c0116c8 | - |
| heal.journalName | Chemische Berichte-Recueil | en |
| heal.journalType | peer reviewed | - |
| heal.language | en | - |
| heal.publicationDate | 1993 | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας | el |
| heal.type | journalArticle | - |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.type.en | Journal article | en |
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