Diisopropylethylamine → (2S,3S,4S)-2-(3-chloro-2-fluoro-benzylcarbamoyl)-4-fluoro-3-methoxy-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To a solution of (2S,3S,4S)-4-fluoro-3-methoxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester and (2R,3R,4R)-3-fluoro-4-methoxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (1.55 g, 5.89 mmol) in CH2Cl2 (50 mL) were added 3-chloro-2-fluoro-benzylamine (1.03 g, 6.48 mmol), propylphosphonic anhydride (50% in EtOAc, 5.20 mL, 8.83 mmol) and DIPEA (3.08 mL, 17.7 mmol). The reaction mixture was stirred at RT for 2 h and concentrated. The crude residue was purified by flash column chromatography on silica gel (c-hexane/EtOAc 7:3) to give (2S,3S,4S)-2-(3-chloro-2-fluoro-benzylcarbamoyl)-4-fluoro-3-methoxy-pyrrolidine-1-carboxylic acid tert-butyl ester: Rf, TLC (c-hexane/EtOAc 1:1)=0.35; MS (UPLC): 405.1/407.2 [M+H]+, 349.1/351.1 [MH−tBu]+, 449.2/451.2 [M+HCOO]−; tR (HPLC conditions f): 2.12 min and (2R,3R,4R)-2-(3-chloro-2-fluoro-benzylcarbamoyl)-3-fluoro-4-methoxy-pyrrolidine-1-carboxylic acid tert-butyl ester: Rf, TLC (c-hexane/EtOAc 1:1)=0.5; MS (UPLC): 405.1/407.2 [M+H]+, 349.0/351.1 [MH−tBu]+, 449.2/451.2 [M+HCOO]−; tR (HPLC conditions f): 2.20 min.

Provenance & Evidence