A mixture of 1H-indazole-5-carboxylic acid (400 mg, 2.47 mmol), 2,2-dimethyloxirane (889 mg, 12.33 mmol) and K2CO3 (1.71 g, 12.33 mmol) in NMP (7 mL) was irradiated with microwave (180° C., 30 min). The mixture was poured into H2O, extracted with EtOAc, dried over Na2SO4, filtered and concentrated. The residual oil was purified by amino gel column chromatography (0-35% EtOAc in hexane) to give 2-hydroxy-2-methylpropyl 1-(2-hydroxy-2-methylpropyl)-1H-indazole-5-carboxylate (468 mg, 62% yield) as a white solid.
