Step 1: 6-Methoxy-3,4-dihydroisoquinolin-1(2H)-one (2.58 g, 14 mmol) was dissolved in dichloromethane at -78 °C and boron tribromide (2.7 mL, 28 mmol) was slowly added. The reaction mixture was gradually warmed to room temperature and stirred overnight. Upon completion of the reaction, the reaction was quenched with cold water and subsequently extracted with ethyl acetate. The organic phases were combined and concentrated in vacuum to remove the solvent. The crude product was purified by ISCO CombiFlash? system using silica gel column chromatography with a dichloromethane solution of 0-15% methanol as eluent to afford 6-hydroxy-3,4-dihydroisoquinolin-1-one as a light brown solid (1.8 g, 75% yield) with a melting point of 204-206 °C; mass spectrum (electrospray ionization) m/z 162.1 [M+H ]+.
[1] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 2, p. 814 - 819
[2] Patent: US2009/69300, 2009, A1. Location in patent: Page/Page column 23
[3] Journal of Medicinal Chemistry, 2012, vol. 55, # 5, p. 2452 - 2468
[4] Patent: US2003/225122, 2003, A1. Location in patent: Page 18-19
[5] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, # 16, p. 4727 - 4730
