反应详情

A solution of crude 17 (˜5 mmol, 1.0 equiv) in THF (25 mL) was cooled in an ice-bath and 3M MeMgBr in Et2O (4.0 mL, 12.0 mmol, 2.4 equiv) was added dropwise via syringe and <5° C. The mixture was stirred at <5° C. for 10 min then allowed to warm to room temperature and stirred 1 hr. The mixture was recooled to ˜8° C. and quenched with saturated NH4Cl solution (5 mL). The mixture was diluted with H2O (20 mL) and extracted with 1:1 EtOAc/heptanes (100 mL). The organic phase was washed with brine (25 mL), dried over Na2SO4, filtered and the solution concentrated under reduced pressure giving a yellow oil. The crude product was dissolved in few mL of dichloromethane/heptanes, absorbed onto silica gel and dry-loaded on a column of silica gel (30 g) packed in heptanes. The column was eluted with heptanes (150 mL), 2% EtOAc/heptanes (250 mL) and 3% EtOAc/heptanes (250 mL). Product fractions were concentrated under reduced pressure to give 1.90 g (93%) of 7 as a nearly colorless oil.

1. stirringstirred 1 hr
2. customwas recooled to ˜8° C.
3. customquenched with saturated NH4Cl solution (5 mL)
4. additionThe mixture was diluted with H2O (20 mL)
5. extractionextracted with 1:1 EtOAc/heptanes (100 mL)
6. washThe organic phase was washed with brine (25 mL)
7. dry with materialdried over Na2SO4
8. filtrationfiltered
9. concentrationthe solution concentrated under reduced pressure
10. customgiving a yellow oil
11. customabsorbed onto silica gel and dry-loaded on a column of silica gel (30 g)
12. washThe column was eluted with heptanes (150 mL), 2% EtOAc/heptanes (250 mL) and 3% EtOAc/heptanes (250 mL)
13. concentrationProduct fractions were concentrated under reduced pressure