Synthesis
The general procedure for the synthesis of 2-chloro-6-hydroxyquinoline from 2-chloro-6-methoxyquinoline is as follows: General method: aryl methyl ether (1.0 eq.) was dissolved in dichloromethane (DCM, 10 mL) and cooled to 0 °C. Boron tribromide (BBr3, 5.0 eq.) was added slowly under stirring. The reaction mixture was stirred at 0 °C and then gradually warmed to room temperature and continued stirring at room temperature for 15 hours. Upon completion of the reaction, the reaction was quenched with sodium bicarbonate (NaHCO3) solution (50 mL) followed by extraction with DCM (4 x 10 mL). The organic layers were combined, washed with water (3 × 10 mL), dried over anhydrous sodium sulfate (Na2SO4), and finally concentrated under vacuum to obtain the target phenolic compounds. 2-Chloro-6-hydroxyquinoline (DHK-6-71) was prepared from 2 g scale of 2-chloro-6-methoxyquinoline using the above general method G. The product was a yellow solid in 93% (1.72 g) yield.
References
[1] Patent: CN102985411, 2016, B. Location in patent: Paragraph 0906-0908
[2] Patent: WO2012/48181, 2012, A1. Location in patent: Page/Page column 74
[3] Patent: WO2012/83165, 2012, A1. Location in patent: Page/Page column 91
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