p-Toluenesulfonic acid → 7-Bromo-1,2-benzothiazole

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Reaction Steps

A mixture of crude 1-[3-bromo-2-(tert-butylsulfanyl)phenyl]-N-hydroxymethanimine (7 g) and p-toluenesulfonic acid (730 mg, 3.88 mmol) in n-butanol (100 mL) was heated to reflux for 16 h. n-Butanol was evaporated, water (100 mL) and saturated aqueous sodium bicarbonate (50 mL) were added and the mixture was extracted with DCM (3×80 mL). The combined organic fractions were dried over anhydrous sodium sulfate, filtered and concentrated to afford 900 mg (17%) of the crude title compound as a brown solid. 1H NMR (300 MHz, CDCl3): δ 7.26-7.40 (t, J=8.1 Hz, 1H), 7.62 (d, J=6.9 Hz, 1H), 8.02 (d, J=8.4 Hz, 1H), 9.04 (s, 1H).

Provenance & Evidence