4-Methoxybenzaldehyde → (R)-2-(5-bromo-2-fluoro-phenyl)-2-(4-methoxy-benzylamino)-propan-1-ol

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Reaction Steps

A solution of (R)-2-amino-2-(5-bromo-2-fluoro-phenyl)-propan-1-ol (5.0 g, 20.2 mmol) and 4-methoxybenzaldehyde (2.8 g, 20.2 mmol) in 1,2-dichloroethane (150 ml) was treated with sodium triacetoxyborohydride (8.81 g, 40.3 mmol) at room temperature. TLC check (eluent: heptane:ethyl acetate=1:1) showed complete reaction after 30 minutes. For the workup, to the reaction mixture were added ethyl acetate (250 ml) and saturated sodium hydrogen-carbonate solution (100 ml). The aqueous layer was separated, and then extracted with ethyl acetate (250 ml). The combined organic layers were washed with saturated sodium chloride solution (100 ml), thereafter dried over sodium sulfate and evaporated at reduced pressure. After chromatography on Silicycle-Si-amine column using a gradient of heptane and ethyl acetate=100/0 to 50/50 as the eluent, (R)-2-(5-bromo-2-fluoro-phenyl)-2-(4-methoxy-benzylamino)-propan-1-ol was obtained as a colorless oil (7.29 g, 98% of theory). Mass (calculated) C17H19BrFNO2 [368.25]; (found) [M+H]+=368, [M+2-H]+=370.

Provenance & Evidence