To a mixture of (Z)-5-((dimethylamino)methylene)-1-phenyl-6,7-dihydro-1H-indazol-4(5H)-one (1 g, 3.74 mmol) and 1-(4-methoxybenzyl)-1H-pyrazol-5-amine (3.5 g, 17.2 mmol) was added trifluoroacetic acid (0.8 mL, 10.3 mmol). The reaction mixture was heated at 100° C. for 2 hours. The reaction mixture was then poured into ice-cooled water (100 mL) and extracted with dichloromethane (3×75 mL). The combined organic extracts were dried using sodium sulfate and concentrated under reduced pressure to give a dark residue. The crude product was purified by flash column chromatography (SiO2, gradient from 100% chloroform to 2% methanol in chloroform) to a residue, which was further purified by crystallization from methanol and isopropanol to give the pure desired product (0.8 g, 15%) as a solid. 1H NMR (CDCl3, 400 MHz): δ 8.33 (s, 1H), 7.87 (s, 1H), 7.78 (s, 1H), 7.55-7.49 (m, 4H), 7.41-7.39 (m, 1H), 7.38 (d, J=8.4 Hz, 2H), 6.83 (d, J=8.4 Hz, 2H), 5.66 (s, 2H), 3.75 (s, 3H), 3.14-3.09 (m, 4H); LCMS [M+H]: 408.
