Thionyl Chloride → 1-(2-Bromoethyl)-5-(chloromethyl)-3-nitro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A 50-mL three-necked round-bottomed flask equipped with a nitrogen inlet and a reflux condenser was purged with nitrogen and charged with 296b (438 mg, 1.76 mmol) and chloroform (10 mL). The reaction was cooled to −5° C. using an ice/acetone bath and SOCl2 (628 mg, 5.28 mmol) was added portion-wise. The cooling bath was removed and the reaction was stirred at 70° C. for 3 h. After this time, the solvent was removed under reduced pressure. ethyl acetate was added to the residue and the resulting solution was cooled to −5° C. Saturated aqueous sodium bicarbonate (3 mL) was added until a pH of 8.5 was reached. The mixture was partitioned between ethyl acetate and water. The combined organic layer was washed with saturated aqueous sodium carbonate (2×5 mL), brine (10 mL), and dried over sodium sulfate. The drying agent was removed by filtration. The filtrate was concentrated under reduced pressure to afford 296c (284 mg, 60%).

Provenance & Evidence