25917-87-7Relevant academic research and scientific papers
o-NITROANILINE DERIVATIVES. PART 10. 5- AND 6-AMINO-1H-BENZIMIDAZOLE 3-OXIDES
McFarlane, Michael D.,Moody, David J.,Smith, David M.
, p. 691 - 696 (2007/10/02)
Cyclisation of N-(4- or 5-acylamino-2-nitrophenyl)glycine esters in basic media gives alkyl 5- or 6-acylaminobenzimidazole-2-carboxylate N-oxides, e.g. (11a) or (11b).Acid hydrolysis of the latter, followed by the reaction of ammonia, gives the title compounds (1b) and (1c), in acceptable yield.The corresponding reaction sequence with 4-acylamino-N-cyanomethyl-o-nitroanilines also gives (1b); where the acyl group is methylsulphonyl, however, the final product is 5-methanesulphonamidobenzimidazole N-oxide (9).Compound (1b) is also obtainable from ethyl 5-nitrobenzimidazole-2-carboxylate N-oxide by reduction followed by hydrolysis.Attempts to cyclise N-(o-nitrophenyl)glycine derivatives containing a free amino group at the 5-position are unsuccessful.This failure is attributed to mesomeric deactivation of the nitro group by the amino lone pair.
Selective Functionalization in 2-Nitro-p-phenylenediamine : Part I - Synthesis of Derivatives of 5-Aminobenzimidazole
Rajappa, S.,Sreenivasan, R.
, p. 533 - 535 (2007/10/02)
2-Nitro-p-phenylenediamine (3) reacts with several electrophilic reagents selectively on the amine meta to the nitro group.The products (4) can be reduced catalytically to the diamines (5) and then cyclized by means of N-carbalkoxy-S-methylpseudothiourea
