26.1 g of 2,3-dimethoxy-5-sulphamoyl-benzoic acid (0.10 mole), 40 ml of water, 200 ml of acetone and 10.1 g of triethylamine (0.10 mole) are placed in 500 ml flask fitted with an agitator, a thermometer and a dropping funnel. The solution is cooled to between 0° and +5° C. and 10.9 g of ethyl chloroformate (0.10 mole) is added drop by drop. It is agitated for 1 hour 30 minutes with the temperature kept at about +5° C., then 19.6 g of 1-cyclohexylmethyl-2 aminomethyl pyrrolidine (0.10 mole) is added drop by drop. A precipitate forms progressively as more and more is added. The reaction medium is then agitated at room temperature, after which it is left to stand. The crystals are filtered, washed three times with water then with 100 ml of 10% ammonia and dried in an oven at 50° C. 50 g is obtained.
