C[O:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[CH2:9][N:8]([CH:13]=[O:14])[CH2:7][C:6]2([CH3:16])[CH3:15].COC1C2C(=CC=CC=2)C(C)(C)CN1C=O.B(Br)(Br)Br>ClCCl>[OH:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[CH2:9][N:8]([CH:13]=[O:14])[CH2:7][C:6]2([CH3:16])[CH3:15]A stirred, cooled (−78° C.) solution of 6-methoxy-4,4-dimethyl-1,2,3,4-tetrahydro-isoquinoline-2-carbaldehyde (Intermediate 19, 3.26 g, 15 mmol) in anhydrous dichloromethane (15 mL) was treated with 1M solution of boron tribromide in dichloromethane (50 mL) stirred at ambient temperature for 3 h. It was then cooled again to 78° C. and quenched carefully with saturated aqueous sodium carbonate solution, diluted with water and the aqueous phase was extracted with ethyl acetate (×2). The combined organic extract was dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to afford the title compound as a solid foam (3 g, 99%).
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