General procedure for the synthesis of 5-hydroxybenzothiazole from 5-methoxybenzo[d]thiazole: Preparation of intermediate 25: A mixture of intermediate 24 (272 mg, 1.65 mmol) with 45% hydriodic acid (2 mL) was heated and refluxed for 5 hours. After completion of the reaction, the mixture was diluted with water and filtered. The filtrate was neutralized, the solid product was collected by filtration, washed with water and combined to give benzo[c]thiazol-5-ol (Intermediate 25) (206 mg, 83% yield). The product was analyzed by high performance liquid chromatography (HPLC) with a purity of 99% and a retention time (RT) of 2.038 min. Mass spectrometry (ESI) analysis showed m/z 152.1 [M + H]+.
