2-Amino-6-methoxybenzothiazole → 2-Amino-6-benzothiazolol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension of 2-amino-6-methoxybenzothiazole (5.00 g, 27.8 mmol) in dichloromethane (70 mL) was cooled to 0° C. under nitrogen and boron tribromide (3.93 mL, 41.6 mmol) was added dropwise. The light yellow mixture was stirred for 3 h, allowing to warm-up slowly from 0° C. to 10° C. The reaction was slowly quenched by dropwise addition of methanol and tafter stirring overnight at room temperature, the white solid was collected by filtration (6.04 g, 88% yield). This hydrobromic salt was dissolved in water, washed with ethyl acetate, and neutralized with a saturated aqueous solution of NaHCO3. The resulting crystals were collected by filtration and dried in the oven at 135° C. for 1 h to afford the title compound 225 as colorless crystals (3.63 g, 79% yield). 1H NMR: (CD3OD) δ (ppm): 7.27 (d, J=8.8 Hz, 1H), 7.08 (d, J=2.2 Hz, 1H), 6.80 (dd, J=8.4, 2.2 Hz, 1H).

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