[Br:1][C:2]1[CH:3]=[C:4]2[C:10]([C:11](N(OC)C)=[O:12])=[N:9][N:8]([CH:17]3[CH2:22][CH2:21][CH2:20][CH2:19][O:18]3)[C:5]2=[N:6][CH:7]=1.[H-].[Al+3].[Li+].[H-].[H-].[H-]>C1COCC1>[Br:1][C:2]1[CH:3]=[C:4]2[C:10]([CH:11]=[O:12])=[N:9][N:8]([CH:17]3[CH2:22][CH2:21][CH2:20][CH2:19][O:18]3)[C:5]2=[N:6][CH:7]=1To a solution of 5-bromo-N-methoxy-N-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamide (XX) (0.290 g, 0.78) in dry THF (5 mL) stirred at 0° C. under nitrogen was added lithium aluminum hydride (36 mg, 0.94 mmol). The solution was further stirred at 0° C. for 30 min. The reaction was quenched with a 0.4 N NaHSO4 solution (10 mL). The solution was extracted with DCM (3×15 mL). The combined organic layer was washed subsequently with water and brine. The organic layer was dried over MgSO4, filtered and concentrated under reduced pressure to produce 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine-3-carbaldehyde (III) as a viscous liquid (218 mg, 0.70 mmol, 91% yield). 1H NMR (CDCl3) δ ppm 1.52-1.74 (m, 2H), 1.95-2.18 (m, 2H), 2.37-2.49 (m, 2H) 3.87-3.98 (m, 1H), 3.99 (m, 1H), 6.18 (dd, J=10.20 Hz, J=2.39 Hz, 1H), 8.73 (d, J=3.01 Hz, 1H), 8.85 (d, J=3.01 Hz, 1H), 10.16 (s, 1H); ESIMS found for C12H12BrN3O2 m/z 310.4 (M+H).
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