Hydrazine hydrate (1:1) → 4-(3-bromo-5-chlorophenoxy)-5-chloro-1H-indazole

Reaction equation

[Br:1][C:2]1[CH:3]=[C:4]([CH:16]=[C:17]([Cl:19])[CH:18]=1)[O:5][C:6]1[C:13]([Cl:14])=[CH:12][CH:11]=[C:10](F)[C:7]=1[CH:8]=O.O.[NH2:21][NH2:22]>C(O)C.O>[Br:1][C:2]1[CH:3]=[C:4]([CH:16]=[C:17]([Cl:19])[CH:18]=1)[O:5][C:6]1[C:13]([Cl:14])=[CH:12][CH:11]=[C:10]2[C:7]=1[CH:8]=[N:21][NH:22]2

Participants

Procedure

To a suspension of 2-(3-bromo-5-chlorophenoxy)-3-chloro-6-fluorobenzaldehyde (77.5 g, 213 mmol) in ethanol (120 mL) was added hydrazine hydrate (31 mL, 639 mmol). The resulting mixture was then heated at reflux for 4 days, after which the mixture was cooled to room temperature, diluted with water (100 mL) and the resulting solid was filtered. The solid was absorbed onto silica gel (300 g) and purified on a silica gel (1500 g) column (0-40% EtOAc/CH2Cl2) to give the title product as a white solid. LRMS (M+1)=358.8