13.4 g of 5-methoxy-2-[1-(4-methoxybenzyl)-1H-indazol-3-yl]-N-(pyridin-4-yl)-pyrimidin-4-amine (1-5-1, 30.6 mmol, 1 eq.) was suspended in 121 ml of 1,2-dichloroethan. First 71 ml of trifluoroacetic acid (918 mmol, 30 eq.) were added dropwise, followed by 27 ml of trifluoromethanesulfonic acid (306 mmol, 10 eq.). The reaction mixture was stirred for three days under nitrogen atmosphere. The mixture was cooled with an ice bath to +3° C., upon which 2M aq. sodium hydroxide solution was added until pH=12. The resulting brown suspension was stirred for 18 hours at room temperature and then the precipitate was filtered off and dried under vacuo at 70° C. to yield 9.74 g (27.7 mmol, 90.3%) of the analytically pure target compound as a light brown solid.
