Chlorosulfonic acid → 5-Bromo-2-oxo-2,3-dihydro-1,3-benzoxazole-6-sulfonyl chloride

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Reaction Steps

To a mixture of commercially-available 5-bromobenzo[d]oxazol-2(3H)-one (35-1, 500 mg, 2.336 mmol) in DCM (23 mLl) at RT was added chlorosulfonic acid (1565 μl, 23.36 mmol). The mixture became a solution that was stirred at RT. After 18 h, The solution was cooled to 0° C. and carefully quenched with ice chips and then partitioned between water (15 mL) and EtOAc (150 mL). The aqueous layer was extracted with 3×30 mL DCM. The combined organics were dried over Na2SO4, filtered, concentrated to give 35-2 as a white solid, which was carried forward without further purification.

Provenance & Evidence