o-Nitroaniline derivatives. Part 11. 4- and 7-Amino-1H-benzimidazole 3-oxides

Abstract

Of the two title compounds, the 4-amino isomer (1a) is easily obtained, either by reduction of the corresponding nitro compound, or in a five-step sequence from 2-nitro-1,3-phenylenediamine. The 7-amino isomer (1d) cannot be obtained by strictly analogous routes but it may be prepared in four steps from 2′,3′-dinitroacetanilide. Attempts to cyanomethylate monoacylated 3-nitro-1,2-phenylenediamines (8) lead to 1-acyl-2,3-dihydro-4-nitrobenzimidazoles (10).