Sulfuric Acid → 1,2-Benzisothiazole-3-carboxylic acid, 6-bromo-5-fluoro-, methyl ester

Participants

Reaction Steps

6-Bromo-5-fluorobenzo[d]isothiazole-3-carboxylic acid (I-25D) (57 mg, 0.21 mmol) was suspended in dry methanol (5 mL) and H2SO4 (0.2 mL) and refluxed for 3 hours. After this time the reaction was cooled to room temperature and diluted with water (3 mL) and neutralized with 5% aquesou Na2CO3 and extracted with ethyl acetate. The organic layer was washed with brine, dried over sodium sulfate and concentrated in vacuo to yield methyl 6-bromo-5-fluorobenzo[d]isothiazole-3-carboxylate (I-25E). MS 289.9 and 291.9 (M+1; Br79/Br81 isotope pattern).

Provenance & Evidence