“…2-(3-Aminophenyl)-1H-benzimidazol-5-amine (32, R 1 = H; R 2 = 3-H 2 NC 6 H 4 ; R 5 = NH 2 ): [194] A mixture of N 2 -(3-aminobenzoyl)benzene-1,2,4-triamine (24.2 g, 0.1 mol) and 4 M HCl (250 mL), or 1 M H 2 SO 4 (500 mL), was heated to its boiling point and maintained at that temperature for 0.5 h. After cooling, the precipitated salt was filtered and adjusted to pH 8.0±8.5 with 4 M NaOH, and the solid product was filtered off, washed with H 2 O, and dried at 102±105 8C, and then at 150 8C to remove H 2 O of crystallization, before final recrystallization (EtOH); yield: 19 g (85%); mp 257±258 8C. N-Alkyl-N-(ethoxycarbonyl)-2-nitroanilines; General Procedure: [197] A stirred soln of the 2-nitroaniline (20 mmol) and ethyl chloroformate (60 mmol) in xylene (30 mL) was heated for 14±18 h under reflux.…”