To a mixture of 5-amino-4-(4-fluorophenyl)-3-(pyridin-4-yl)pyrazole (100 mg) and concentrated hydrochloric acid (0.2 ml) in water (0.4 ml) was added sodium nitrite (28 mg) in water (0.12 ml) under ice cooling. The mixture was stirred for 30 minutes and to the mixture were added cold dichloromethane (5 ml), an aqueous saturated sodium bicarbonate (2 ml) solution and 1-(triphenylphosphoranylidene)-2-propanone (126 mg) in dichloromethane (2 ml). The mixture was stirred at 10° C. for 2 hours. The organic layer was separated, dried and concentrated in vacuo. The residue was purified by column chromatography on silica gel and the obtained oil was crystallized from diisopropyl ether to give 8-(4-fluorophenyl)-4-methyl-7-(pyridin-4-yl)pyrazolo[5,1-c][1,2,4]triazine (41 mg).
