Boron tribromide → 6-Hydroxy-4,4-dimethyl-1,2,3,4-tetrahydro-isoquinoline-2-carbaldehyde

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Reaction Steps

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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