1-(3-fluorobenzyl)-5-nitro-1H-indazole → 1-(3-Fluorobenzyl)-1H-indazol-5-amine

Reaction equation

[N+:1]([C:4]1[CH:5]=[C:6]2[C:10](=[CH:11][CH:12]=1)[N:9]([CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[C:16]([F:20])[CH:15]=1)[N:8]=[CH:7]2)([O-])=O>C(O)(=O)C.CCOC(C)=O.[Fe]>[NH2:1][C:4]1[CH:5]=[C:6]2[C:10](=[CH:11][CH:12]=1)[N:9]([CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[C:16]([F:20])[CH:15]=1)[N:8]=[CH:7]2

Participants

Procedure

5-nitro-1-N-(3-fluorobenzyl)indazole (7.9 g, 29.1 mmol, 1 equiv) and iron (8.13 g, 145.6 mmol, 5 equiv) were mixed in 200 mL acetic acid and 50 mL EtOAc, and were stirred at rt for 36 h. The reaction mixture was filtered through a pad of Celite®. The filtrate was concentrated in vacuo to 10 mL volume. The contents were diluted with water (10 mL) and neutralized with saturated Na2CO3 solution. The solution was extracted with EtOAc (3×500 mL), the combined organic layers dried over MgSO4, filtered, and concentrated in vacuo. The resulting crude material was purified by column chromatography eluting with hexanes/EtOAC (4:1 to 3:1) to give 5-amino-1-N-(3-fluorobenzyl)indazole (5.32 g, 76%) as a light brown solid. 1H-NMR (DMSO-d6) δ 7.72 (s, 1H), 7.22-7.36 (m, 2H), 6.87-7.05 (m, 3H), 6.70-6.77 (m, 2H), 5.48 (s, 2H), 4.78 (br s, 2H); LCMS RT=1.66 min; [M+H]+=242.2.