[F:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[N:7][N:8]2[C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])=[CH:4][C:3]=1[CH:18]=[O:19].[BH4-].[Na+]>CO.O.CCOC(C)=O>[OH:19][CH2:18][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][C:2]=1[F:1])[N:8]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[N:7]=[CH:6]2A solution of tert-butyl 6-fluoro-5-formyl-1H-indazole-1-carboxylate (29E, 3.55 g, 13.4 mmol) in methanol (50.00 mL) was treated with NaBH4 (1.02 g, 26.9 mmol) at 0° C. and stirred for 1 h. The reaction mixture was diluted with water and EtOAc (500 mL). The organic layer was separated and washed with aq. HCl (1M, 200 mL), aq. NaOH (1M, 200 mL) brine (200 mL) dried (MgSO4), filtered, concentrated in vacuo and residue was purified using chromatography (SiO2, EtOAc/hexanes) to yield tert-butyl 5-(hydroxymethyl)-6-fluoro-1H-indazole-1-carboxylate (29F, 3.00 g; Yield=83.9%) as a colorless solid.
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