[N+](C1C=CC(N)=C(N)C=1)([O-])=O.[CH:12]1([C:15]2[NH:16][C:17]3[CH:23]=[C:22]([N+:24]([O-])=O)[CH:21]=[CH:20][C:18]=3[N:19]=2)[CH2:14][CH2:13]1.[N+](C1NC2C=CC=CC=2N=1)([O-])=O>C1(C(O)=O)CC1.CCOC(C)=O.CO.[Pd]>[CH:12]1([C:15]2[NH:16][C:17]3[CH:23]=[C:22]([NH2:24])[CH:21]=[CH:20][C:18]=3[N:19]=2)[CH2:14][CH2:13]1A solution of 4-nitro-1,2-phenylenediamine (1.0 g, 6.6 mmol) in 15 ml of cyclopropanecarboxylic acid was stirred at reflux for 12 h. The reaction mixture was concentrated in vacuo to yield a oil, which was dissolved in 100 ml of EtOAc and washed with aqueous NaHCO3. Organic layer was dried over MgSO4 and concentrated in vacuo, yielding an oil which was characterized as 2-cyclopropyl-5-nitrobenzimidazole and subjected to a following reaction without further purification. The nitrobenzimidazole and 50 mg of 10% Pd-C were dissolved in 100 ml of MeOH and stirred for 12 h under H2. The reaction mixture was filtered and concentrated in vacuo to provide 0.87 g (4.9 mmol, 75%) of the desired product.
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