(S)-Tert-butyl 2,2-dimethyl-4-(2-oxoethyl)oxazolidine-3-carboxylate → (S)-4-((S)-2-hydroxy-propyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid t-butyl ester

To a cooled solution of (S)-2,2-dimethyl-4-(2-oxo-ethyl)-oxazolidine-3-carboxylic acid t-butyl ester (2.05 g, 8.43 mmol) in dry tetrahydrofuran (25 mL) was added 1.4M methyl magnesium bromide in diethyl ether (6.02 mL) at −78° C. The mixture was stirred at −78° C. for 30 min and then warmed to −5° C. The mixture was extracted with diethyl ether and ammonium chloride solution. The organic layer was dried and concentrated. The crude mixture was purified by ISCO flash chromatography (0 to 60% ethyl acetate/hexanes) to give two fractions. The first fraction afforded (S)-4-((S)-2-hydroxy-propyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid t-butyl ester as a colorless oil (870 mg): 1H NMR (300 MHz, CDCl3) δ ppm 1.20 (d, J=6.0 Hz, 3H), 1.42-1.60 (m, 1H), 1.50 (s, 12H), 1.55 (s, 3H), 1.68-1.88 (m, 1H), 3.66 (d, J=8.8 Hz, 1H), 3.69-3.80 (m, 1H), 3.94-4.08 (m, 1H), 4.17-4.30 (m, 1H), 4.62 (br. s., 1H); The second fraction afforded (S)-4-((R)-2-hydroxy-propyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid t-butyl ester as a white solid (740 mg): 1H NMR (300 MHz, CDCl3) δ ppm 1.22 (d, J=6.0 Hz, 3H), 1.49 (s, 12H), 1.58 (br. s., 3H), 1.75-1.90 (m, 2H), 2.56 (br. s., 1H), 3.75-3.93 (m, 2H), 3.95-4.05 (m, 1H), 4.03-4.20 (m, 1H).

1. temperaturewarmed to −5° C
2. extractionThe mixture was extracted with diethyl ether and ammonium chloride solution
3. customThe organic layer was dried
4. concentrationconcentrated
5. customThe crude mixture was purified by ISCO flash chromatography (0 to 60% ethyl acetate/hexanes)
6. customto give two fractions

ORD 기록

ord-c998ee0b7cbd49e2aca538f3ae03d3e0

출처 데이터셋

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

특허 번호

US07741327B2