General procedure for the synthesis of tert-butyl (R)-but-3-yn-2-ylcarbamate from Boc-L-alaninal and dimethyl (1-diazido-2-oxopropyl)phosphonate:
1. Boc-L-alaninal (500 mg, 2.89 mmol), dimethyl (1-diazido-2-oxopropyl)phosphonate (610 mg, 3.18 mmol, 1.1 eq.) and potassium carbonate (638 mg, 4.62 mmol, 1.6 eq.) were dissolved in methanol (14.4 mL).
2. The reaction mixture was stirred at room temperature for 18 hours.
3. Upon completion of the reaction, the reaction mixture was diluted with ethyl acetate (30 mL) and saturated aqueous sodium chloride solution (40 mL).
4. The organic and aqueous layers were separated and the aqueous layer was further extracted with ethyl acetate (30 mL).
5. Combine all organic extracts, dry with anhydrous sodium sulfate, filter and concentrate.
6. The product was purified by silica gel column chromatography (eluent: 20% ethyl acetate in heptane solution) to give tert-butyl (R)-but-3-yn-2-ylcarbamate (0.258 g, white solid) in 53% yield.
7. The product was characterized by 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).
