[C:1]([O:5][C:6](=[O:12])[NH:7][C@@H:8]([CH3:11])[CH:9]=O)([CH3:4])([CH3:3])[CH3:2].[CH3:13]OP(C(=[N+]=[N-])C(=O)C)(=O)OC.C(=O)([O-])[O-].[K+].[K+]>CO.C(OCC)(=O)C.[Cl-].[Na+]>[CH3:11][C@H:8]([NH:7][C:6](=[O:12])[O:5][C:1]([CH3:4])([CH3:3])[CH3:2])[C:9]#[CH:13]A solution of (S)-tert-butyl(1-oxopropan-2-yl)carbamate (500 mg, 2.89 mmol), dimethyl(1-diazo-2-oxopropyl)phosphonate (610 mg, 3.18 mmol, 1.1 equiv), and potassium carbonate (638 mg, 4.62 mmol, 1.6 equiv) in methanol (14.4 mL) was stirred at room temperature for 18 hours. The reaction was then diluted with ethyl acetate (30 mL) and saturated aqueous sodium chloride (40 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (30 mL) and the combined organic extracts were dried over Na2SO4, filtered and concentrated. Silica gel column chromatography (20% EtOAc in Heptane) provided (S)-tert-butyl but-3-yn-2-ylcarbamate (0.258 g, white solid) in 53% yield. 1H NMR (400 MHz, CDCl3) δ 4.49 (m, 1H), 2.26 (d, J=2.2 Hz, 1H), 1.46 (s, 9H), 1.41 (d, J=6.8 Hz, 3H).
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