2-Nitro-1H-benzimidazole → 2-cyclopropyl-1H-benzimidazol-5-amine

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Reaction Steps

A 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.

Provenance & Evidence