Hydrochloric Acid → 1-(4-Bromophenyl)-2,4,4,4-tetrafluoro-1,3-butanedione

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Reaction Steps

To a solution of 1-(4-bromophenyl)-2-fluoro-1-ethanone (3.54 g, 16.3 mmol) in tetrahydrofuran (50 ml) was added dropwise 1M lithium hexamethyldisilazide tetrahydrofuran solution (19.6 ml, 19.6 mmol) at −78° C. After stirring for 45 min., N-trifluoroacetylimidazole (2.3 ml, 19.6 mmol) was added. The resulting mixture was allowed to warm up to room temperature and stirred for 1.5 hr. The mixture was acidified with 2M hydrochloric acid and extracted with diethyl ether (300 ml). The separated organic layer was washed with water (100 ml×3) and dried over magnesium sulfate. The solution was evaporated to give 5.2 g of 1-(4-bromophenyl)-2,4,4,4-tetrafluoro-1,3-butanedione as a brown oil. This residue was heated with 5-hydrazino-2-pyrisinesulfonamide hydrochloride (1.10 g, 4.89 mmol) at refluxing temperature for 18 hr. After evaporation, the obtained residue was chromatographed on a column of silica gel (500 g) eluting with ethyl acetate/hexane (1:3 to 1:1) to afford 930 mg (12%) of the title compound as a yellow solid.

Provenance & Evidence