反应详情

5-Amino-7-cyano4-methylbenzimidazole (4 g) is prepared treating a heterogeneous solution of 7-cyano-4-methyl-5-nitrobenzimidazole (0.91 g, 0.0045 mol) and 10% Pd/C (100 mg) in methanol (200 mL) with an atmosphere of H2 (1 atm, balloon) for 14 hr. The resulting mixture is filtered through celite and concentrated via rotary evaporation to give rise to a yellow residue. This residue is chromatographed (silica gel, 95:5 ethyl acetate:methanol) to give rise to 5-amino-7-cyano4-methylbenzimidazole. 5-amino-7-cyano-4-methylbenzinidazole N-methoxycarbonyl-2-thiomethyl-2-imidazoline (4.45 g, 1.1 eq.) (prepared as described in Example 2) are dissolved in acetonitrile (100 mL) and glacial acetic acid (10 mL), and the reaction mixture is stirred at 70° C. until the coupling step is complete. The reaction mixture is diluted with methanol (50 mL) and refluxed until deprotection is complete, and then the acetonitrile is evaporated under reduced pressure. The acetic acid solution obtained is dissolved in water (9.25 mL) and the resulting mixture is cooled to 0° C. A 5 molar aqueous solution of H2SO4 (5.1 mL) is added dropwise to the cold mixture. The solution is then heated to 65° C. and absolute ethanol is added until cloudiness is observed. The mixture is allowed to come to room temperature and is then cooled to 5° C. The solid obtained is filtered, washed with ethanol and dried to provide N-(4,5-dihydro-1H-imidazol-2-yl)-7-cyano-4-methyl-1H-benzimidazol-5-amine as its sulfuric acid salt.

1. filtrationThe resulting mixture is filtered through celite and
2. concentrationconcentrated via rotary evaporation
3. customto give rise to a yellow residue
4. customThis residue is chromatographed (silica gel, 95:5 ethyl acetate:methanol)
5. customto give rise to 5-amino-7-cyano4-methylbenzimidazole