Acetic Anhydride → 5-bromo-3-cyano-2-(4-fluorophenyl)-6-nitro-2H-indazole 1-oxide

Participants

Reaction Conditions

Reaction Steps

To a stirred suspension of 5-bromo-2,4-dinitrobenzaldehyde (6.5 g, 0.024 mol) in acetic acid (120 mL) was added 4-fluoroaniline (9.28 g, 0.054 mol) and the reaction mixture was heated to 60° C. to get a clear solution. To this was added sodium cyanide portionwise (6.0 g, 0.123 mol) and the reaction mixture was stirred at 60° C. for 5 min. Acetic anhydride (1.9 mL, 0.020 mol) was added and the reaction mixture was stirred for 5 min at the same temperature. Sodium cyanide (6.0 g, 0.123 mol) was then added at the same temperature at which time the product precipitated out. After stirring for 30 min, the mixture was cooled to RT, diluted with water (50 mL), filtered and washed with ethanol to afford crude product, which was purified by flash column chromatography eluting with PE/EtOAc (100/1) to give pure 5-bromo-3-cyano-2-(4-fluorophenyl)-6-nitro-2H-indazole 1-oxide (5.0 g, 56%). 1H-NMR (CDCl3, 400 MHz) δ 8.40 (s, 1H), 8.15 (s, 1H), 7.67˜7.70 (m, 2H), 7.38˜7.42 (m, 2H). MS (M+H)+: 377/379.

Provenance & Evidence