General procedure for the synthesis of tert-butyl (R)-(1-hydroxybut-3-en-2-yl)carbamate from (R)-N-Boc-2,2-dimethyl-4-vinyl oxazolidine: vinyl oxazolidine 11 (500 mg, 2.2 mmol) was dissolved in ethanol (10 mL) under ice-bath cooling conditions, and p-toluenesulfonic acid monohydrate (42 mg, 0.22 mmol). The reaction mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, the reaction was quenched with aqueous sodium bicarbonate and extracted with ethyl acetate (3 x 10 mL). The organic phases were combined, washed sequentially with saturated aqueous sodium bicarbonate (2 x 10 mL) and brine (10 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by column chromatography (eluent: hexane-ethyl acetate, v/v 9:1) to give 330 mg (80% yield) of colorless oily target compound. The 1H NMR and 13C NMR spectra of the product were in agreement with literature data [59]. Infrared spectra (ATR, cm?1) ν: 3344, 2998, 2932, 1692, 1522, 1366, 1171, 1053; 1H NMR (400 MHz, CDCl3) δ: 5.81 (m, 1H, =CH?), 5.25 (m, 2H, =CH2), 4.94 (br s, 1H, NH), 4.25 ( br s, 1H, CH?N), 3.65 (m, 2H, CH2?OH), 2.39 (br s, 1H, OH), 1.46 (s, 9H, Boc); 13C NMR (100 MHz, CDCl3) δ: 156.0, 135.4, 116.6, 79.8, 65.2, 54.7, 28.3; high-resolution mass spectra ( ESI): calculated value C9H17NO3Na [M+Na]+ m/z 210.1106, measured value 210.1109.
