Acetic Acid → (3R*,4S*)-4-Benzylamino-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester

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Reaction Steps

To a solution of (RS)-4-oxo-pyrrolidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester (commercial; 1 g, 3.9 mmol) in EtOH (15 mL) were added benzylamine (0.85 mL, 7.77 mmol) and AcOH (0.45 mL, 7.77 mmol) and the mixture was stirred 3 h at rt. Sodium cyanoborohydride (0.98 g, 15.5 mmol) was then added at rt and the mixture was heated to 75° C. for 5 h, then 15 h to 50° C. and again 1 h to 75° C. The mixture was concentrated under reduced pressure, water was added and the mixture extracted 3× with EA. The combined org. extracts were washed with brine dried over MgSO4 and concentrated under reduced pressure. The residue was purified by CC (Hep/EA from 2:1 to 1:1) to afford the title intermediate as a yellow oil (0.73 g, 54%).

Provenance & Evidence