[Br:1][C:2]1[CH:3]=[C:4]2[C:10]([C:11]([N:13]([O:15][CH3:16])[CH3:14])=[O:12])=[N:9][NH:8][C:5]2=[N:6][CH:7]=1.[O:17]1[CH:22]=[CH:21][CH2:20][CH2:19][CH2:18]1.CC1C=CC(S([O-])(=O)=O)=CC=1.C1C=C[NH+]=CC=1>C(Cl)Cl>[Br:1][C:2]1[CH:3]=[C:4]2[C:10]([C:11]([N:13]([O:15][CH3:16])[CH3:14])=[O:12])=[N:9][N:8]([CH:18]3[CH2:19][CH2:20][CH2:21][CH2:22][O:17]3)[C:5]2=[N:6][CH:7]=1To a solution of 5-bromo-N-methoxy-N-methyl-1H-pyrazolo[3,4-b]pyridine-3-carboxamide (XIX) (0.250 g, 0.88 mmol) in dry DCM (10 mL) was added 3,4-dihydro-2H-pyran (0.179 mL, 1.98 mmol) and PPTS (22 mg, 0.08 mmol) and refluxed 5 h under nitrogen. Another equivalent of 3,4-dihydro-2H-pyran (0.179 mL, 1.98 mmol) and PPTS (22 mg, 0.08 mmol) was added and the solution was further heated at refluxed overnight under nitrogen. The solution was cooled, diluted with DCM, washed subsequently with a saturated aqueous NaHCO3 solution and brine. The organic layer was dried over MgSO4, filtered and concentrated under reduced pressure to give 5-bromo-N-methoxy-N-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamide (XX) as a viscous liquid (302 mg, 0.82 mmol, 93% yield). 1H NMR (CDCl3) δ ppm 1.51-1.62 (m, 2H), 1.91-2.13 (m, 2H), 2.33-2.44 (m, 2H), 3.40 (s, 3H), 3.66 (m, 1H), 3.75 (s, 3H), 3.87-3.98 (m, 1H), 6.07 (dd, J=10.07 Hz, J=2.52 Hz, 1H), 8.57 (d, J=3.01 Hz, 1H), 8.73 (d, J=3.01 Hz, 1H); ESIMS found for C14H17BrN4O3 m/z 369.4 (M+H).
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