2.5- Dimethoxy-4-nitroaniline

Transfer hydrogenation of aromatic nitro compounds. Aromatic nitro compounds are reduced to anilines when refluxed in excess cyclohexene in the presence of ordinary commerical 10% Pd/C catalyst. The method is very useful for selective reduction of polynitrobenzenes. Halogen, if present, is eliminated. Cyclohexene is superior to cyclohexa-1,3-diene as hydrogen donor. The reaction is usually successful, but slower, with sulfur-containing substrates. 4-Methoxy-2,5-dinitroanisole is reduced to 2,5-dimethoxy-4-nitroaniline in 10 min. in the steam bath under these conditions. 

When an analogous strategy was used for the synthesis of pyrrolo[l,2-fl] quinoxaline from 3,6-dimethoxy-2-nitroaniline, 6,9-dimethoxypyrrolo[l,2-a] quinoxaline 191c, interesting in view of the presence of the methoxy groups, was obtained under the right conditions, it was converted into 6,9-dihydroxypyrrolo [ 1,2-a]quinoxaline and pyrrolo[l,2-a]quinoxaline-6,9-dione 192 (Scheme 3.57). 

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