[Br:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]=[N:5][NH:6]2.CC1C=CC(S(O)(=O)=O)=CC=1.O.[O:23]1[CH:28]=[CH:27][CH2:26][CH2:25][CH2:24]1>C1COCC1>[Br:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]=[N:5][N:6]2[CH:24]1[CH2:25][CH2:26][CH2:27][CH2:28][O:23]1A mixture of 4-bromo-1H-indazole (0.5 g, 2.53 mmol), p-TsOH.H2O (50 mg, 0.25 mmol), and 3,4-dihydro-2H-pyran (0.64 g, 7.61 mmol) in THF (20 mL) was degassed then heated to reflux overnight. After the solvent was removed, the residue was partitioned between DCM (300 mL) and water (50 mL). The organic layer was separated, dried (MgSO4), filtered and concentrated. The crude residue was purified by SiO2 chromatography eluting with a DCM/MeOH gradient (0.5 to 1% MeOH) to afford 570 mg (81%) of 4-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole (196) as yellow solid: MS (ESI) m/z=282.2 [M+1]+.
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