Oxidative Nucleophilic Substitution of Hydrogen versus Ring-Opening in the Reaction of 4-R-2-Nitrothiophenes with Amines. The Crucial Effect of 4-Alkyl Groups

4-Alkyl-2-nitrothiophenes [10:  R = CH3, CH(OH)CH3, CH(OCH3)CH3] react with secondary aliphatic amines, in the presence of AgNO3, to give 3-alkyl-2-amino-5-nitrothiophenes (12) through an oxidative nucleophilic substitution of hydrogen (ONSH) of synthetic interest. This behavior is in striking contr...

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Veröffentlicht in:Journal of organic chemistry 2007-07, Vol.72 (15), p.5771-5777
Hauptverfasser: Bianchi, Lara, Maccagno, Massimo, Petrillo, Giovanni, Sancassan, Fernando, Tavani, Cinzia, Morganti, Stefano, Rizzato, Egon, Spinelli, Domenico
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Sprache:eng
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Zusammenfassung:4-Alkyl-2-nitrothiophenes [10:  R = CH3, CH(OH)CH3, CH(OCH3)CH3] react with secondary aliphatic amines, in the presence of AgNO3, to give 3-alkyl-2-amino-5-nitrothiophenes (12) through an oxidative nucleophilic substitution of hydrogen (ONSH) of synthetic interest. This behavior is in striking contrast with that of the parent 2-nitrothiophene (6), which was found to undergo ring-opening in analogous reaction conditions. A possible rationale for the crucial effect of alkyl groups is suggested, grounded also on a study of the corresponding Meisenheimer-like adducts.
ISSN:0022-3263
1520-6904
DOI:10.1021/jo070610i