반응 #1069840

반응 방정식

(R)-2-(α-Benzoxycarbonylethyl)-4,5-dehydro-1,2-oxazinan-3-one

(R)-2-(3-Oxo-3,6-dihydro-[1,2]oxazin-2-yl)-propionic acid benzyl ester

AD-mix-β

tert-butanol

Sodium sulfite

methanesulfonamide

→

product 8a

수율 81.0%

(αR,4S,5S)-2-(α-Benzoxycarbonylethyl)-4,5-dihydroxy-1,2-oxazinan-3-one

수율 81.0%

용매

water

반응 조건

후처리

1. 1
   workup.ADDITIONwas added
2. 2
   workup.ADDITIONwas added in one portion
3. 3
   기타to quench the oxidation
4. 4
   workup.STIRRINGstirring
5. 5
   workup.WAITwas continued for 1 h at RT
6. 6
   workup.ADDITIONCH2Cl2 (10 mL) was added
7. 7
   기타the upper organic layer was separated off
8. 8
   추출The aqueous phase was extracted with CH2Cl2 (5×5 mL)
9. 9
   건조The combined organic extracts were dried over MgSO4
10. 10
    기타After removal of the solvent
11. 11
    기타the yellowish semisolid residue was purified
12. 12
    건조by dry flash chromatography (Silica Gel 60H for TLC, 15% EtOAc-hexanes→EtOAc)

실험 절차

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).

출처