Crampton, M. R. and Lunn, R. E. A. and Lucas, D. (2003) 'sigma-adduct formation and oxidative substitution in the reactions of 4-nitrobenzofurazan and some derivatives with hydroxide ions in water.', Organic & biomolecular chemistry., 1 (19). pp. 3438-3443.
The reactions of hydroxide ions with 4-nitrobenzofurazan, 1a, 4-nitrobenzofuroxan, 1b, and with three 4-nitro-7-substituted benzofurazans have been examined using H-1 NMR and UV-visible spectroscopies. In each case initial reaction is at the 5-position to give an anionic sigma-adduct. Kinetic and equilibrium results are reported. NMR spectra show that in the case of 1a oxidation of the anionic adduct yields 4-nitro-5-hydroxybenzofurazan. In the case of 1b rearrangement of the 5-hydroxy adduct to the thermodynamically more stable 7-hydroxy adduct, possibly by a Boulton-Katritzky mechanism, precedes oxidation. When the 7-substituent in the 4-nitrobenzofurazan is Cl, OMe or OPh the eventual product is 7-hydroxy-4-nitrobenzofurazan produced by nucleophilic displacement of the substituent.
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|Publisher Web site:||http://dx.doi.org/10.1039/b307648m|
|Record Created:||10 May 2007|
|Last Modified:||08 Apr 2009 16:31|
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