122 g (233 mmol) of 5-isopropyl-pyridine-2-sulfonic acid [6-chloro-2-(2-cyano-pyridine-4-yl)-5-(2-methoxy-phenoxy)-pyrimidine-4-yl]-amide was suspended in 450 ml of N,N-dimethyl formamide and the mixture was cooled down to 15° C. At this temperature, 35 ml of hydrazine hydrate were added dropwise within 1 hr. The resulting solution was stirred at 15° C. to 20° C. for 16 hr and thereafter diluted with 600 ml of de-ionized water. Then 50 ml of glacial acetic acid were added dropwise at 0° C. to 5° C. until pH=5.5. 600 g of ice were added and the suspension was stirred for 1 hr. The solid was filtered off under suction, washed with 3000 ml of water and dried at 40° C., 2000 Pa for 24 hr. There were obtained 126 g (97% of theory) of 5-isopropyl-pyridine-2-sulfonic acid [6-chloro-2-[2-(hydrazino-imino-methyl)-pyridine-4-yl]-5-(2-methoxy-phenoxy)-pyrimidine-4-yl]-amide with a HPLC purity of 91.8% (w/w).
