The remarkable effect of 7-amino substituents on the reactivity of 4-nitrobenzofurazans with nucleophiles
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Date
2005
Authors
Crampton, M.R.
Isanbor, C.
Willett, T.C.
Journal Title
Journal ISSN
Volume Title
Publisher
NRC Research Press
Abstract
The reactions of four 4-nitrobenzofurazans (4a–4d) substituted at the 7 position with (a) N-ethyl, (b) Nbutyl, (c) piperidino, or (d) pyrrolidino groups have been examined with sulfite ions and with hydroxide ions in water–
DMSO (80:20, v/v). Addition of sulfite at the 5 position gives σ adducts with equilibrium constants ca. 105 lower than
that for the formation of the corresponding adduct from 4-nitrobenzofurazan. These reductions are attributed to the stabilization of the parent molecules 4a–4d by conjugative interaction between the 4 and 7 substituents. In alkaline solution, 4a and 4b yield the conjugate bases while 4c and 4d suffer nucleophilic substitution to give 7-hydroxy-4-
nitrobenzofurazan. Reactivity here is relatively high because of the iminium ion character of the substrates.
Description
Keywords
Research Subject Categories::NATURAL SCIENCES::Chemistry::Physical chemistry::Spectroscopy , benzofurazans , σ adducts , nucleophilic reactivity , substitution
Citation
Crampton, M. R., Isanbor, C., & Willett, T. C. (2005). The remarkable effect of 7-amino substituents on the reactivity of 4-nitrobenzofurazans with nucleophiles. Canadian journal of chemistry, 83(9), 1222-1227.