Eliminations from (E)-2,4-Dinitrobenzaldehyde O-Aryloximes Promoted by R3N in MeCN. Effects of β-Aryl Group and Base-Solvent on the Nitrile-Forming Transition-State

Nitrile-forming eliminations from (E)-2,4-(NO2)2C6H2CH=NOC6H4-2-X-4-NO2 (1a-e) promoted by R3N in MeCN have been studied kinetically. The reactions are second-order and exhibit Brönsted β = 0.83-1.0 and |βlg| = 0.41-0.46. The results have been interpreted in terms of highly E1cb-like transition stat...

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Veröffentlicht in:Bulletin of the Korean Chemical Society 2012, 33(9), , pp.2976-2980
Hauptverfasser: Bong Rae Cho, Eun Mi Ryu, Sang Yong Pyun
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Sprache:eng
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Zusammenfassung:Nitrile-forming eliminations from (E)-2,4-(NO2)2C6H2CH=NOC6H4-2-X-4-NO2 (1a-e) promoted by R3N in MeCN have been studied kinetically. The reactions are second-order and exhibit Brönsted β = 0.83-1.0 and |βlg| = 0.41-0.46. The results have been interpreted in terms of highly E1cb-like transition state with extensive Cβ- H bond cleavage and limited Nα-OAr bond cleavage. Comparison with existing data reveals that the structure of the transition state changes from E2-central to highly E1cb-like either by the change of the β-aryl group from Ph to 2,4-dinitrophenyl under the same condition or by the base-solvent system variation from EtO−-EtOH to Et3N-MeCN for a given substrate (1a-e). KCI Citation Count: 2
ISSN:0253-2964
1229-5949
DOI:10.5012/bkcs.2012.33.9.2976