Benzenesulfonamide → 6-Benzenesulfonylcarbamoyl-1-(2-chlorobenzyl)-2-methylbenzimidazole

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Reaction Steps

N,N′-carbonyldiimidazole (45.8 g) is added all at once to an N,N-dimethyl-formamide (950 ml) solution of 6-carboxy-1-(2-chlorobenzyl)-2-methylbenzimidazole (45.0 g) (example 75), and the solution is stirred for one hour at room temperature. Subsequently, benzenesulfonamide (47.1 g) and diazabicycloundecene (35.0 g) are added, and the solution is stirred for 70 hours at 100° C. The reaction solution is cooled and the solvent is removed through evaporation under reduced pressure. Water (300 ml) and methanol (200 ml) are added to the residue, and moreover, 35% hydrochloric acid is added to adjust the acidity of the solution to pH 5.5. Precipitated crystals are separated through filtration, washed with a mixture solution (200 ml) of methanol and water (1/1), dried and thus, 6-benzenesulfonylcarbamoyl-1-(2-chlorobenzyl)-2-methylbenzimidazole (38.4 g) is obtained. In addition, water is added to filtrates and crystals precipitated. The crystals are separated through filtration, washed with water, dried and thus, of the material (13.3 g) is obtained. Both sets of crystals are gathered and dissolved by adding acetone (3300 ml) and water (900 ml) and by heating. The solvent is removed through evaporation as this solution is heated. Then the solution is cooled. Precipitated crystals are separated through filtration, dried, and thus, of 6-benzenesulfonylcarbamoyl-1-(2-chlorobenzyl)-2-methylbenzimidazole (33.8 g) is obtained. 1H-NMR (DMSO-d6δ): 2.53 (3H, s), 5.46 (2H, s), 6.34 (1H, d, J=7.8 Hz), 7.11 (1H, m), 7.27 (1H, m), 7.48 (1H, m), 7.52 (2H, m), 7.60 (1H, m), 7.69 (1H, d, J=8.6Hz), 7.90 (1H, m), 8.09 (2H, m), 8.11 (1H, s), 11.84 (1H, br s).

Provenance & Evidence