4-Nitroindazole → NoName_3327

Participants

Reaction Steps

A mixture of 4-nitro-1H-indazole (200 g, 1.22 moles) and 10% palladium on carbon (20.0 g,) in EtOH (3000 ml) was hydrogenated at ambient temperature (reaction was exothermic and temperature increased to 50° C.). After completion of reaction, the catalyst was removed by filtration. The solvent was evaporated under vacuum at below 80° C. and cooled to room temperature and n-hexane (1000 ml) was added to the residue and stirred for 30 min. Isolated solid was filtered and washed with n-hexane (200 ml). Product was dried under vacuum at 70-80° C. for 10-12 h to give 4-amino-1H-indazole as a brown solid (114 g, 70%), m. p.: 136-143° C. 1H NMR (200 MHz, CDCl3) δ 12 (br, 1H), 8.0 (s, 1H), 7.1-7.0 (dd, 2H), 6.5 (d, 1H), 3.9 (m, 2H). ESMS m/z 134 (M+1). Purity: 90-95% (HPLC)

Provenance & Evidence