In 70 ml of methylene chloride were dissolved 3.24 g of 2-(N-methyl-N-benzylamino)ethylamine and 2.0 g of triethylamine, and to the solution was added dropwise 50 ml of a methylene chloride solution containing 3.0 g of 5-isoquinolinesulfonyl chloride under cooling with ice. After the dropwise addition of the methylene chloride solution, the mixed solution was stirred at a temperature of 15° C. to 25° C. for one hour, and then the reaction solution was washed with water and extracted with a 10% aqueous hydrochloric acid solution. The aqueous layer was washed with chloroform, rendered alkaline with a 1N aqueous sodium hydroxide solution, extracted with chloroform, and then the chloroform layer was washed with water, dried with anhydrous magnesium sulfate and the chloroform was distilled therefrom under reduced pressure. The residue thus obtained was subjected to a silica gel column chromatography (silica gel:100 g; solvent:chloroform) to give 3.84 g of N-[2-(N-methyl-N-benzylamino)ethyl]-5-isoquinolinesulfonamide, i.e., Compound (65) in a yield of 84%.
