Synthesis
Concentrated sulfuric acid (0.543 g, 5.53 mmol) was slowly added to a stirred solution of indazole-3-acetic acid (4.86 g, 27.5 mmol) in methanol (250 mL). The reaction mixture was refluxed at 68 °C for 16 h, during which the reaction progress was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the methanol was evaporated to dryness by rotary evaporator. The residual gel was alkalized to pH 7-8 with saturated sodium bicarbonate solution and subsequently extracted with ethyl acetate (3 x 50 mL). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated by rotary evaporator under reduced pressure to give methyl 2-(1H-indazol-3-yl)acetate (4.90 g, 25.7 mmol, 93% yield) as a light brown solid.
References
[1] Patent: WO2017/197046, 2017, A1. Location in patent: Page/Page column 328
[2] Bioorganic and Medicinal Chemistry Letters, 2011, vol. 21, # 24, p. 7344 - 7350
[3] Tetrahedron, 2012, vol. 68, # 48, p. 10049 - 10058,10
[4] Tetrahedron, 2012, vol. 68, # 48, p. 10049 - 10058
[5] Tetrahedron, 2012, vol. 68, # 49, p. 10180 - 10187
