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温度

0 °C

(S)-4-(2-Hydroxy-pent-4-enyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (2.54 g, 8.91 mmol) was dissolved in dry tetrahydrofuran (60 mL). Sodium hydride (60% suspension in mineral oil, 360 mg) was added. The mixture was stirred at 0° C. for 5 min. Then allylbromide (1.60 mL) was added. The mixture was stirred at room temperature for 18 h. Solvents were evaporated and the residue was extracted with diethyl ether and citric acid solution. The organic layer was washed with saturated sodium chloride solution and concentrated. The crude material was purified through flash column chromatography (silica gel, 5-30% ethyl acetate/hexanes) to afford (S)-4-(2-allyloxy-pent-4-enyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid t-butyl ester (1.38 g, 48% yield for two steps) as an oil: 1H NMR (300 MHz, CDCl3) δ ppm 1.48 (s, 12H), 1.56, 1.60 (2×s, 3H), 1.64-1.77 (m, 1H), 1.80-2.07 (m, 1H), 2.32 (br. s., 2H), 3.48 (br. s., 1H), 3.79-4.23 (m, 5H), 4.98-5.19 (m, 3H), 5.26 (d, J=17.2 Hz, 1H), 5.72-5.98 (m, 2H).

1. stirringThe mixture was stirred at room temperature for 18 h
2. customSolvents were evaporated
3. extractionthe residue was extracted with diethyl ether and citric acid solution
4. washThe organic layer was washed with saturated sodium chloride solution
5. concentrationconcentrated
6. customThe crude material was purified through flash column chromatography (silica gel, 5-30% ethyl acetate/hexanes)