General procedure for the synthesis of 4-(hydroxymethyl)-1H-indazole from methyl indazole-4-carboxylate: synthesis of (1H-indazol-4-yl)-methanol (18b): the ester obtained above (40 mg, 0.23 mmol) was dissolved in 1 mL of tetrahydrofuran (THF) and the solution was cooled to 0°C. A THF solution (1.0 M, 2.3 mL, 2.3 mmol) of diisobutylaluminum hydride (DIBAL) was added slowly and dropwise. The addition of DIBAL was continued until the feedstock was completely consumed. Upon completion of the reaction, the reaction was quenched with saturated sodium potassium tartrate solution and gradually warmed to room temperature. The reaction mixture was extracted using ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate (MgSO4). Subsequently, the solvent was removed by reduced pressure distillation and the residue was purified by column chromatography (75% ethyl acetate/hexane). The final target product (20 mg, 60% yield) was obtained as a white solid. Mass spectrometry (electrospray ionization) analysis showed that the theoretical value of M + H = 149.1 and the measured value = 149.1.
