4-Methoxybenzenesulfonamide → 1-(2-Chlorobenzyl)-6-(4-methoxybenzenesulfonylcarbamoyl)-2-methylbenzimidazole

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Reaction Steps

N,N′-carbonyldiimidazole (0.431 g) is added all at once to an N,N-dimethylformamide (15 ml) solution of 6-carboxy-1-(2-chlorobenzyl)-2-methylbenzimidazole (0.400 g) (example 75), and the solution is stirred for one hour at room temperature. Subsequently, an N,N-dimethylformamide (5 ml) solution of 4-methoxybenzenesulfonamide (0.498 g) and diazabicycloundecene (0.405 g) is added, and the solution is stirred for 67 hours at 100° C. The reaction solution is cooled and the solvent is removed through evaporation under reduced pressure. Water and chloroform are added to the residue. While being stirred, 10% hydrochloric acid is added until the aqueous layer became acidic. The organic layer, which is obtained through chloroform extraction (twice), is washed with a saturated sodium bicarbonate aqueous solution, and the solvent is removed through evaporation under reduced pressure. After purification using silica gel column chromatography (eluate: chloroform/methanol=100/2˜100/10) and then concentration, crystals are formed in a mixture solution of ethyl acetatc and diethylether. The crystals are separated through filtration, dried, and thus, 1-(2-chlorobenzyl)-6-(4-methoxybenzenesulfonylcarbamoyl)-2-methylbenzimidazole (0.450 g) is obtained.

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