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General procedure for the synthesis of 2-chloro-3-hydroxyquinoline from 2-chloroquinoline-3-boronic acid: Step 1: 2-Chloroquinoline-3-boronic acid (15 g, 72.3 mmol) was suspended in Et2O/H2O (600 mL) and NH4Cl (7.16 g, 134 mmol) was added. Subsequently, 30% H2O2 aqueous solution (62 mL, 709 mmol) was added dropwise. The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the precipitate was collected by filtration, washed sequentially with H2O and Et2O, and then dried over P2O5 at 60 °C to afford 2-chloro-3-hydroxyquinoline (11.5 g, 89% yield). lCMS (ES+) m/z 180 ([M+H]+).

[1] Patent: WO2008/57209, 2008, A1. Location in patent: Page/Page column 58-59
[2] Patent: EP2268285, 2018, B1. Location in patent: Paragraph 0182; 0183