methyl 4-amino-1H-indazole-1-carboxylate hydrochloride synthesis

Yield:-

Reaction Conditions:

Stage #1: 4-nitroindazole-1-carboxylic acid methyl esterwith hydrogen;5%-palladium/activated carbon in methanol at 20; under 2068.65 Torr; for 1.5 h;
Stage #2: with hydrogenchloride in methanol;water;

Steps:

24C

Example 24C; methyl 4-amino-1H-indazole-1-carboxylate; The product of Example 24B (1.66 g, 7.5 mmol) and 10% Pd/C were combined in ethanol (20 mL) and exposed to a hydrogen atmosphere. The reaction mixture was heated at 80° C. for 20 minutes, allowed to cool to room temperature, and filtered through Celite. The filtrate was evaporated to provide title compound. ¹H NMR (300 MHz, DMSO-d₆) δ 6.1 (s, 2H), 6.41 (dd, 1H), 7.21 (m, 2H), 8.42 (s, 1H). Alternatively, to the reaction vessel was charged the product of Example 24B, MeOH (2000 mL), and 5% Pd/C (10.6 g). The mixture was pressured with H₂ (40 psi) and shaken at ambient temperature. The reaction was completed in 1.5 hours. The mixture was filtered to obtain the product in MeOH. Conc., 37% HCl (100 mL) was added to the reaction mixture. The product solution was concentrated to furnish a light brown solid. The solid was reslurried in isopropyl alcohol (200 mL) for 15 minutes. The solid was filtered and washed with fresh isopropyl alcohol (3×50 mL), and dried in a vacuum oven to provide 94.9 g of 4-aminoindazole-1-carboxylic acid methyl ester, HCl salt as a light brown solid.

References:

US2006/128689,2006,A1 Location in patent:Page/Page column 18