tert-Butanol → (alphaR,4S,5S)-2-(alpha-Benzoxycarbonylethyl)-4,5-dihydroxy-1,2-oxazinan-3-one

Participants

Reaction Steps

A mixture of K2OsO2(OH)4 (0.0063 g, 0.017 mmol), (DHQD)2PHAL (0.032 g, 0.041 mmol), and AD-mix-β (1.41 g) was dissolved in a mixture of tert-butanol (5 mL) and water (5 mL). After dissolution of the salts, methanesulfonamide (0.0994 g, 1.04 mmol) was added and the mixture was cooled to −2˜0° C. (R)-2-(α-Benzoxycarbonylethyl)-4,5-dehydro-1,2-oxazinan-3-one (7a) (0.264 g, 1.01 mmol) was added in one portion and the heterogeneous slurry was stirred vigorously for 14 h at −2˜+2° C. Sodium sulfite (1.5 g) was added in order to quench the oxidation and stirring was continued for 1 h at RT. CH2Cl2 (10 mL) was added and the upper organic layer was separated off. The aqueous phase was extracted with CH2Cl2 (5×5 mL). The combined organic extracts were dried over MgSO4. After removal of the solvent, the yellowish semisolid residue was purified by dry flash chromatography (Silica Gel 60H for TLC, 15% EtOAc-hexanes→EtOAc) to afford 0.158 g (81%) the product 8a as a white solid. 1H NMR (400 MHz) in CDCl3+2 drops of CD3OD (J, Hz): δ 1.53 (3H, d, 3J=7.3, α-MeCH), 3.96 (1H, dd, 2J=−11.8, 3J=2.5, 6-HA), 4.41 (1H, d, 3J=4.1, 4-H), 4.44 (1H, dd, 2J=−11.8, 3J=6.8, 6-HB), 4.55-4.51 (1H, m, 5-H), 5.11 (1H, q, 3J=7.3, α-CH), 5.13 (1H, s, CH2Ph), 7.34-7.24 (5H, m, Ph).

Provenance & Evidence