BBr3 (1.0 M in CH2Cl2, 10.5 mL, 10.5 mmol) was slowly added dropwise to a solution of 2-[4-(N-monomethyl)aminophenyl]-6-methoxybenzothiazole (44,588 mg, 2.06 mmol) dissolved in dichloromethane (25 mL). The reaction mixture was stirred continuously for 12 hours at room temperature. Upon completion of the reaction, water and aqueous sodium bicarbonate were carefully added to quench the reaction, followed by extraction of the organic phase with dichloromethane. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford 2-[4-(N-monomethyl)aminophenyl]-6-hydroxybenzothiazole (45,530 mg, 99% yield) as a yellow solid, which did not require further purification. The structure of the product was confirmed by 1H NMR (200 MHz, DMSO-d6) and 13C NMR (100 MHz, DMSO-d6).
