1-((Tert-butoxy)carbonyl)-4,4-difluoropyrrolidine-2-carboxylic acid → tert-Butyl (2S)-4,4-difluoro-2-(hydroxymethyl)pyrrolidine-1-carboxylate

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Reaction Steps

To a solution of 4,4-difluoro-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester (Compound 2a) (1.5 g; 6.0 mmol) in tetrahydrofuran (15 mL) was added borane-dimethylsulfide complex (3.79 mL; 7.58 mmol) dropwise at ambient temperature. The reaction mixture was refluxed for 2 h. The resultant mixture was allowed to cool to room temperature. The mixture was partitioned between EtOAc and H2O. The organic phase was washed with H2O, and then dried over Na2SO4. The mixture was filtered and the filtrate was evaporated under reduced pressure to give the crude material. The crude material was purified by flash column chromatography (SiO2), eluting with a heptane-EtOAc gradient to afford Compound 2b (1.2 g; 84% yield) as a colorless oil. 1H-NMR (400 MHz, CDCl3): δ4.08-4.23 (m, 2H), 3.61-3.87 (m, 4H), 2.45-2.57 (m, 1H), 2.15 (br.s, 1H), 1.49 (s, 9H).

Provenance & Evidence