Dimethylformamide → (2S,4S)-4-(9H-fluoren-9-ylmethoxycarbonylamino)-pyrrolidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester

Beteiligte Stoffe

Reaktionsschritte

To a suspension of (2S,4S)-4-(9H-fluoren-9-ylmethoxycarbonylamino)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (Aldrich) (1 g, 2.21 mmol) in methanol (6 mL) was added a solution potassium carbonate (153 mg, 1.1 mmol) in water (6 mL) dropwise. The mixture was stirred at room temperature for 1 hour, concentrated, and the residue slurried in toluene and evaporated to dryness 3 times and once from diethyl ether to give a white solid. The solid was mixed with DMF (6 mL), and bromomethyl-benzene (289 μL, 2.43 mmol) was added dropwise at room temperature. After 16 hours the mixture was diluted with water extracted with ethyl acetate. The combined extracts were washed with water, brine and dried over anhydrous magnesium sulfate and concentrated. The residue was purified by silica gel chromatography to give (2S,4S)-4-(9H-fluoren-9-ylmethoxycarbonylamino)-pyrrolidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester (0.92 g, 77%) as a foam.

Herkunft & Nachweise