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

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Reaction Steps

To a solution of (2S,3S,4S)-4-fluoro-3-methoxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (500 mg, 1.90 mmol) in DMF (20 mL) were added 3-chloro-2-fluoro-benzylamine (330 mg, 2.1 mmol), HBTU (1.4 g, 3.8 mmol) and DIPEA (1.32 mL, 7.6 mmol). The reaction mixture was stirred at RT for 2 h then was poured into water (50 mL). After extraction with ETOAc (3×30 mL), the organic phases were joined, washed with brine, dried over Na2SO4, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (c-hexane to c-hexane/EtOAc 1:1) 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)=0.37; 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. 1H NMR (400 MHz, DMSO-d6) δ (ppm): 8.59 (m, 1H), 7.48 (m, 1H), 7.37 (m, 1H), 7.20 (m, 1H), 5.20 (br.d, 1H), 4.47-4.26 (m, 3H), 4.19 (ddd, 1H), 3.81-3.65 (m, 1H), 3.54-3.40 (m, 1H), 3.36 (s, 3H), 1.42 and 1.27 (2 s, 9H).

Provenance & Evidence