Chlorosulfonic acid → Benzo[c]isothiazole-7-sulfonyl chloride

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Reaction Steps

Benzo[c]isothiazole 24B (1 g, 7.45 mmol) was added dropwise to chlorosulfonic acid (5.5 mmol) at 0° C. After the addition was complete, the mixture was stirred at room temperature for 0.5 h and then heated at 105° C. and stirred overnight. The resulting mixture was cooled to −10° C. and quenched by pouring on crushed ice slowly. The resulting mixture was extracted with EtOAc (100 mL×2). The combined organic phase was washed with brine, dried over anhy. Na2SO4 and concentrated in vacuo. Column chromatography (15% PE/EtOAc) afforded 200 mg of title compound. 1H NMR (CHLOROFORM-d) δ: 9.68 (s, 1H), 8.66 (d, J=1.9 Hz, 1H), 8.10 (d, J=9.4 Hz, 1H), 7.99 (dd, J=9.4, 2.1 Hz, 1H).

Provenance & Evidence