o-Nitroaniline derivatives. Part 8. Synthesis of some unsymmetrical dimethylquinoxalines: a long-standing problem resolved

Abstract

Reduction of N-acetonyl-4-methyl-2-nitro-N-p-tolylsulphonylaniline, using tin(II) chloride in hydrochloric acid, gives 2,7-dimethylquinoxaline (42%) together with di-p-tolyl disulphide and toluene-p-thiol. 2,6- and 2,5-Dimethylquinoxalines are similarly obtained from the appropriately substituted nitro-anilines; the 2,8-dimethyl isomer, however, is obtained impure and in very low yield.