Hydrogen Peroxide → 6-Benzyloxy-2,3-dibromo-benzo[b]thiophene 1-oxide

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Reaction Steps

Dissolve 6-benzyloxy-2,3-dibromo-benzo[b]thiophene (20 g, 50 mmol) in dichloromethane (88 mL) and add trifluoroacetic acid (88 mL). Stir for 10 minutes, then add 30% aqueous solution of hydrogen peroxide (5.1 mL, 50 mmol) and stir for 4 hours. Add solid sodium bisulfite (2.2 g, 21 mmol), dilute with water (30 mL), stir for 15 minutes, and then concentrate in vacuo. Partition residue between dichloromethane (150 mL) and saturated aqueous sodium bicarbonate (150 mL), separate layers, wash organic layer with additional saturated aqueous sodium bicarbonate (150 mL) and brine (100 mL). Dry with sodium sulfate, filter, and concentrate in vacuo. Chromatograph on a SiO2 column eluting with 100% dichloromethane to give 12.8 g of 6-benzyloxy-2,3-dibromo-benzo[b]thiophene 1-oxide (62%).

Provenance & Evidence