反应详情

Solid K2CO3 (16.3 g, 0.12 mol, 1.2 equiv) was added to a solution of crude 14 (20.6 g, ˜0.10 mol, 1.0 equiv) in DMF (200 mL) followed by benzyl bromide (17.1 g, 11.9 mL, 0.10 mol, 1.0 equiv). The yellow suspension was heated at to 80° C.-90° C. for 4.5 hr. The mixture was cooled to room temperature and stirred for 48 hr. The mixture was poured into H2O (750 mL) and the aqueous mixture extracted with EtOAc (500 mL). The organic phase was diluted with heptanes (500 mL) and the solution washed with H2O (3×250 mL), brine (300 mL), dried over Na2SO4, filtered and the solution concentrated under reduced pressure giving brown oil that crystallized. The crude product was absorbed onto silica gel using dichloromethane and dry-loaded on a column of silica gel (250 g) packed in heptanes. The column was eluted with heptanes (1 L), 2.5% EtOAc/heptanes (2 L) and 5% EtOAc/heptanes (2 L). Product-containing fractions were concentrated under reduced pressure. The slightly oily solid was pumped on high vacuum for 0.5 hr, then triturated with cold heptanes (100 mL), filtered, washed with a small volume of heptanes and dried to give 17.8 g (62%) of 15 as a white solid.

1. temperatureThe yellow suspension was heated at to 80° C.-90° C. for 4.5 hr
2. extractionthe aqueous mixture extracted with EtOAc (500 mL)
3. additionThe organic phase was diluted with heptanes (500 mL)
4. washthe solution washed with H2O (3×250 mL), brine (300 mL)
5. dry with materialdried over Na2SO4
6. filtrationfiltered
7. concentrationthe solution concentrated under reduced pressure
8. customgiving brown oil
9. customthat crystallized
10. customThe crude product was absorbed onto silica gel
11. washThe column was eluted with heptanes (1 L), 2.5% EtOAc/heptanes (2 L) and 5% EtOAc/heptanes (2 L)
12. concentrationProduct-containing fractions were concentrated under reduced pressure
13. waitThe slightly oily solid was pumped on high vacuum for 0.5 hr
14. customtriturated with cold heptanes (100 mL)
15. filtrationfiltered
16. washwashed with a small volume of heptanes
17. customdried