Ammonium Chloride → 2-(R)-(2-(S)-Dibenzylamino-1-(S)-hydroxy-3-phenylpropyl)-5,5-dimethylpyrrolidine-1-carboxylic acid tert-butyl ester

Beteiligte Stoffe

Reaktionsschritte

Add sec-butyllithium (2.9 mL, 2.1 mmol) dropwise to a solution of freshly distilled (−)-sparteine (1 mL, 4.3 mmol) in diethyl ether (25 mL) over 3 min at −78° C. Add 2,2-dimethylpyrrolidine-1-carboxylic acid tert-butyl ester (645 mg, 3.2 mmol) in diethyl ether (2 mL) dropwise over 10 min. Stir 2 h, add 2-(S)-dibenzylamino-3-phenylpropionaldehyde (967 mg, 2.9 mmol) in diethyl ether (2 mL) over 5 min and stir 20 min. Add saturated aqueous ammonium chloride solution and ethyl acetate and let warm to room temperature, separate the layers, extract the aqueous layer with ethyl acetate, wash the organic layer with saturated aqueous sodium chloride solution, dry (magnesium sulfate), concentrate and purify (silica gel chromatography, eluting with 4:1 hexanes:ethyl acetate) to give the title compound as a colorless oil (182 mg, 12%).

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