[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][N:6]=[CH:5]2.C([O-])([O-])=O.[K+].[K+].Br[CH2:18][CH:19]([CH3:21])[CH3:20]>CN(C=O)C>[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH2:18][CH:19]([CH3:21])[CH3:20])[N:6]=[CH:5]2The crude 5-bromo-1H-indazole (compound 2f, 100 mmol) was dissolved in 250 mL of DMF. K2CO3 (20.7 g, 150 mmol) and 1-bromo-2-methylpropane (16.3 mL, 150 mmol) were added. The mixture was heated to 120° C. under nitrogen atmosphere for 16 hours. The mixture was cooled to room temperature and concentrated under reduced pressure. Water (200 mL) and CH2Cl2 (200 mL) were added to the residue and stirred vigorously for 30 minutes. The layers were separated and the aqueous layer was extracted with CH2Cl2. The combined extracts were dried over anhydrous MgSO4, filtered through Celite, and concentrated under reduced pressure to provide about 30 g of crude material. The crude material was purified by chromatography (1:9 to 1:4 ether/hexanes) to provide 12.870 g of compound 3f as a dark red oil, yielding 50.8% for steps A and B. MS ESI (+) m/z 253 and 255 (M+1) detected. 1H-NMR (400 MHz, CDCl3) δ 7.93 (s, 1H), 7.87 (m, 1H), 7.43 (m, 1H), 7.29 (m, 1H), 7.29 (m, 1H), 4.15 (m, 2H), 2.33 (m, 1H), 0.92 (m, 6H).
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