1186334-61-1

1114809-02-7

1186334-61-1

Step 2: 6-bromo-3-chloro-2-fluorobenzaldehyde (1.0 g, 4.24 mmol) was dissolved in 1,2-dimethoxyethane (DME, 5 mL), followed by hydrazine hydrate (5 mL). The reaction mixture was heated to reflux for 3 h. After completion of the reaction, it was cooled to room temperature. The solvent was evaporated under reduced pressure and water (100 mL) was added to the residue and extracted with ethyl acetate (3 x 30 mL). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to afford 4-bromo-7-chloro-1H-indazole in 51% yield. Mass spectrum (MS): m/z 230.9 [M + H]+.