3-Methylbutanal → 2-(R)-[2-(R)-(Benzhydrylidene-amino)-1-(S)-hydroxy-3-phenylpropyl]-4-(3-methyl-butyl)-piperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

Dissolve (2-(R)-[2-(R)-(benzhydrylidene-amino)-1-(S)-hydroxy-3-phenylpropyl]-piperazine-1-carboxylic acid tert-butyl ester (167 mg, 0.33 mmol) in 1,2-dichloroethane (2.5 mL) and add 3-methylbutyraldehyde (0.042 mL, 0.41 mmol). After 5 min, add sodium triacetoxyborohydride (100 mg, 0.47 mmol) and stir for 1 h. Add saturated aqueous sodium bicarbonate solution (5 mL) and stir for 10 min. Add ethyl acetate and separate the layers. Extract the aqueous layer with ethyl acetate, combine the organic layers, wash the organic layer with saturated aqueous sodium chloridesolution, dry (magnesium sulfate), concentrate and purify (silica gel chromatography, eluting with ethyl acetate) to give the title compound as a colorless oil (165 mg, 87%).

Provenance & Evidence