Benzyl Bromide → 1-Benzyl-5,6-dichloro-1H-benzimidazole-2-amine

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Reaction Steps

2-Amino-5,6-dichlorobenzimidazole (4) (1 g, 4.95 mmole) was dissolved in acetonitrile (200 ml) and NaOH (198 mg, 4.95 mmole) was added. After stirring for 1 hr at room temperature, benzyl bromide (0.589 ml, 4.95 mmole) was added and the mixture was allowed to stir overnight. The mixture was concentrated under reduced pressure and purified on a silica gel column (3.5×5 cm) using 5% MeOH/CHCl3 to give 1.23 g (85%) of 2-amino-1-benzyl-5,6-dichlorobenzimidazole (182). The compound was then recrystallized from EtOH/H2O to give a white powder. 1H NMR (DMSO-d6): d 5.28 ppm (s, 2H), 6.95 (s, 2H), 7.16 (d, 2H), 7.25 (d, 1H), 7.31 (m, 4H). 13C NMR (DMSO-d6): d 44.74 ppm, 109.15, 115.37, 119.62, 122.66, 126.82, 127.37, 128.55, 134.10, 136.46, 143.13, 156.91. MS (Electron Impact): m/e 291, 200, 158, 91, 65. MP: 245°-246° C. Elemental Analysis: (C14H11Cl2N3,): Calculated: C, 57.55; H, 3.79; N, 14.38. Found: C, 57.66; H, 3.83; N, 13.98. UV imax nm (e×104): (pH 7) 230 (0.761), 260 (0.324), 302 (0.452); (pH 1) 238 (0.306), 294 (0.383), 299 (0.359); (pH 11) 229 (0.869), 257 (0.316), 301 (0.443).

Provenance & Evidence