反应详情

To a solution of (3aS,4R,5R,6R,7aS)-4,5-bis(benzyloxy)-6-((benzyloxy)methyl)hexahydrobenzo[d]oxazol-2(3H)-one (3.00 g, 6.34 mmol) in acetic anhydride (60 mL) and acetic acid (10 mL) was added anhydrous ZnCl2 (8.62 g, 63.4 mmol). The mixture was stirred at room temperature for 3 h. Most of the solvents were removed by evaporation under high vacuum. The residue was diluted with aqueous saturated NaHCO3 (200 mL) and extracted with EtOAc (2×50 mL). The extracts were washed with brine, dried with MgSO4. The solvent was evaporated to give white foam. This was dissolved in MeOH (50 mL) and K2CO3 (1.75 g, 12.7 mmol) was added. The mixture was stirred at room temperature for 2 h. Solvent was evaporated. The residue was diluted with water (50 mL) and extracted with DCM (2×30 mL). The extracts were washed with brine, dried with MgSO4. The solvent was evaporated to give white foam which was purified by a silica gel column, eluting with 5% MeOH in DCM to give 3aS,4R,5R,6R,7aS)-4,5-bis(benzyloxy)-6-(hydroxymethyl)hexahydrobenzo[d]oxazol-2(3H)-one as a white solid (1.86 g, 77%). 1H NMR (400 MHz, CDCl3) δ 7.33-7.42 (m, 10H), 4.95 (d, J=11.8 Hz, 1H), 4.89 (d, J=10.9 Hz, 1H), 4.82 (s, 1H), 4.69 (d, J=11.3 Hz, 1H), 4.64-4.69 (m, 1H), 4.60 (d, J=11.8 Hz, 1H), 3.72-3.77 (m, 1H), 3.50-3.56 (m, 3H), 3.40 (t, J=9.1 Hz, 1H), 2.12 (dt, J=15.3 Hz, 3.1 Hz, 1H), 1.91-1.98 (m, 1H), 1.69-1.77 (m, 1H), 1.55 (t, J=4.9 Hz, 1H).

1. customMost of the solvents were removed by evaporation under high vacuum
2. additionThe residue was diluted with aqueous saturated NaHCO3 (200 mL)
3. extractionextracted with EtOAc (2×50 mL)
4. washThe extracts were washed with brine
5. dry with materialdried with MgSO4
6. customThe solvent was evaporated
7. customto give white foam
8. stirringThe mixture was stirred at room temperature for 2 h
9. customSolvent was evaporated
10. additionThe residue was diluted with water (50 mL)
11. extractionextracted with DCM (2×30 mL)
12. washThe extracts were washed with brine
13. dry with materialdried with MgSO4
14. customThe solvent was evaporated
15. customto give white foam which
16. customwas purified by a silica gel column
17. washeluting with 5% MeOH in DCM