[CH:1]1([C:4]([N:6]2[C:15]3[C:10](=[C:11]([O:16]C)[CH:12]=[CH:13][CH:14]=3)[CH2:9][CH2:8][C@@H:7]2[CH3:18])=[O:5])[CH2:3][CH2:2]1.[B]>ClCCl>[CH:1]1([C:4]([N:6]2[C:15]3[CH:14]=[CH:13][CH:12]=[C:11]([OH:16])[C:10]=3[CH2:9][CH2:8][C@@H:7]2[CH3:18])=[O:5])[CH2:2][CH2:3]1A 1000-mL round-bottom flask was charged with (2S)-1-cyclopropanecarbonyl-5-methoxy-2-methyl-1,2,3,4-tetrahydroquinoline (15.0 g, 61.2 mmol) and dichloromethane (300 mL). A solution of boron tribomide (1 M in dichloromethane, 308 mL, 308 mmol) was added dropwise at 0° C., and the resulting solution stirred for 1 h at 0° C. The reaction mixture was then poured into 500 mL of water/ice and extracted with dichloromethane (2×500 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was purified via column chromatography on silica gel (eluting with 0-80% ethyl acetate/petroleum ether) to afford (2S)-1-cyclopropanecarbonyl-2-methyl-1,2,3,4-tetrahydroquinolin-5-ol (9.4 g, 66%) as an off-white solid. MS (ES, m/z): 232 [M+H]+
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