Ammonia → (S)-4-((R)-1,1-difluoropropan-2-yl)oxazolidin-2-one

To liquid ammonia at −50° C. under argon was slowly added a solution of (S)-3-benzyl-4-((R)-1,1-difluoropropan-2-yl)oxazolidin-2-one (627 mg) (200 mg, 0.784 mmol) in diethylether (10 mL). Lithium (pellets; 54.4 mg, 7.84 mmol) were added in three portions. The reaction mixture became green then dark greenish blue over ˜10 min. The mixture was stirred for additional 15 min and then quenched slowly by the addition of saturated aqueous ammonium chloride solution (3 mL). The mixture was allowed to warm slowly to room temperature. The residue was diluted with diethylether (20 mL) and water (10 mL). The separated aqueous layer was extract with ether (2×25 mL) and DCM (3×20 mL). The DCM and ether layers were separately concentrated under reduced pressure. The residues were dissolved in DCM and combined. The organic layer was dried over magnesium sulfate, filtered off and concentrated under reduced pressure providing crude (S)-4-((R)-1,1-difluoropropan-2-yl)oxazolidin-2-one (114 mg) as a colorless solid, which was directly used without further purification. MS m/z 166.1 (M+H)+; Rt-0.37 min.