1H-Indazole-3-carboxamide(6CI,7CI,9CI)

Synthesis

General procedure for the synthesis of 1H-indazole-3-carboxamide from indazole-3-carboxylic acid: indazole-3-carboxylic acid (0.3 g, 1.86 mmol) was dissolved in anhydrous THF (7 mL) under nitrogen protection. To this solution, isobutyl chloroformate (0.39 g, 2.94 mmol) and N-methylmorpholine (NMM) (0.297 g, 2.94 mmol) were added sequentially. The reaction mixture was stirred at -20 °C for 2 hours. Subsequently, 5 mL of ammonia solution was added to the reaction system and the mixture was continued to be stirred at room temperature for 1 hour. Upon completion of the reaction, the reaction mixture was diluted with ethyl acetate (5 mL) and subsequently washed with water (2 x 10 mL). The organic phase was dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by column chromatography with the eluent dichloromethane/methanol (95:5, v/v) to afford the white crystalline product 1H-indazole-3-carboxamide (0.41 g, 85% yield) with a melting point of 284-286 °C. The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6, with TMS as internal standard): δ 7.22 (t, 1H, 1H J = 15.00 Hz), 7.32 (s, 1H), 7.40 (t, 1H, J = 14.32 Hz), 7.59 (d, 1H, J = 8.40 Hz), 7.71 (s, 1H), 8.16 (d, 1H, J = 8.16 Hz), 13.51 (s, 1H).

References

[1] Patent: US2012/130078, 2012, A1. Location in patent: Page/Page column 2-3
[2] Chemical Biology and Drug Design, 2012, vol. 79, # 4, p. 488 - 496
[3] Patent: CN103626705, 2016, B. Location in patent: Paragraph 0041; 0042; 0043; 0044
[4] ChemMedChem, 2013, vol. 8, # 5, p. 722 - 725
[5] Patent: WO2017/98328, 2017, A2