Tin(II) chloride selectively reduces the aromatic nitro group to the amino group, the azoxy group remaining intact. This allows the preparation of 2-(R-NNO-azoxy)anilines from 2-(R-NNO-azoxy)nitrobenzenes bearing electron-donating or weak electron-withdrawing substituents (Me or Br) in the benzene ring and alkyl substituents at the distal N atom of the azoxy group. The presence of electron-withdrawing substituents at the azoxy group (for example, CO2Et) leads to a change in the direction of the reaction resulting in selective reduction of the azoxy group to the hydrazo group.
作者:O. Yu. Smirnov、A. M. Churakov、Yu. A. Strelenko、S. L. Ioffe、V. A. Tartakovsky
DOI:10.1023/a:1021344300420
日期:——
Benzo-1,2,3,4-tetrazine 1,3-dioxide (BTDO) and its derivatives were nitrated with HNO3/H2SO4 or HNO3/oleum and brominated with dibromoisocyanuric acid in CF3CO2H/H2SO4 (5 : 1) or H2SO4. The reactivity of positions in the benzene ring of this heterocyclic system as regards electrophilic substitution was found to change in the following order: 5 approximate to 7 > 8 > 6. Mono- and dinitro-BTDOs and mono- and polybromo-BTDOs were synthesized. Their structures were confirmed by H-1, C-13, and N-14 NMR spectra.