On the application of the extended Fujita-Nishioka equation to polysubstituted systems. A kinetic study of the rearrangement of several poly-substituted Z-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles in dioxane/water

Francesca D'Anna, Gabriella Macaluso, Vincenzo Frenna, Susanna Guernelli, Giovanni Petrillo, Camilla Zaira Lanza, Fiammetta Ferroni, Domenico Spinelli, Raffaella Spisani, Giovanni Petrillo, Vitalba Pace

Risultato della ricerca: Articlepeer review

25 Citazioni (Scopus)

Abstract

The rearrangement rates of several di-, tri-, tetra- or penta-substituted Z-arylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1a-18a) into the relevant 2-aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles (1b-18b) have been determined in 1:1 (v:v) dioxane/water in a wide range of pS + (3.80-12.50) at different temperatures. The kinetic data obtained have been correlated with those previously collected for the rearrangement of ortho-, meta- and para-substituted Z-arylhydrazones (19a-38a) by means of an extension of the linear free-energy relationship (LFER) proposed by Fujita and Nishioka, thus considering steric (E s) and field (F o) proximity effects in addition to the normal electronic effects (σ o,m,p). Excellent correlation coefficients have been calculated (R≥0.999), with susceptibility constants (ρ, δ and f) close to those previously obtained for 19a-38a, when only excluding data for the 2,6-bis-ortho-substituted Z-arylhydrazones 11a and 16-18a, which show a reactivity much higher than foreseeable, evidencing the first case of 'steric acceleration' in mononuclear rearrangements of heterocycles. A rationale for such a behaviour is proposed.
Lingua originaleEnglish
pagine (da-a)167-178
Numero di pagine12
RivistaTetrahedron
Volume61
Stato di pubblicazionePublished - 2005

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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