反应详情

温度

-75 °C

A solution of propargyl 4-pyridyl ether (prepared according to (Thummel et al, J. Org. Chem. 1978, 43 4882) (173 mg, 1.3 mmol) in dry THF (15 mL) was treated with n-BuLi (2.5M in THF, 1,3 mmol, 0.52 mL) at −70° C. After stirring the mixture at −75° C. for 0.5 hr, a solution of 5β-pregnan-3,20-dione, cyclic 20-(1,2-ethanediyl acetal) (180 mg, 0.5 mmol) in THF (15 mL) was added and the mixture was stirred at −78° C. for 20 min. The cooling bath was removed and the stirring was continued at rt for 1 hr. The mixture was quenched with NH4Cl solution (2 mL). The solvent was removed and the residue was then dissolved in acetone (25 mL). After adding 2N HCl (2 mL) the s olution was stirred at rt for 20 min. Sat. NaHCO3 soln. was added to neutralize the acid. The solvents were removed and the residue was extracted with EtOAc. The organic layer was washed with water, and brine. After drying over anhyd. MgSO4 the solution was filtered and evaporated to yield the crude product (250 mg). This crude product was then dissolved in a small amount of CH2Cl2 and poured on a column of silica gel. Elution with CH2Cl2:acetone mixture (90:10) gave 3α-hydrocy-3β-[3-4′-pyridinyloxy)-1-propynyl]-5β-pregnan-20-one (145 mg) as a colorless solid; mp 84-90° C.; TLC Rf (CH2Cl2:acetone 85:15)=0.17.

1. stirringthe mixture was stirred at −78° C. for 20 min
2. customThe cooling bath was removed
3. waitthe stirring was continued at rt for 1 hr
4. customThe mixture was quenched with NH4Cl solution (2 mL)
5. customThe solvent was removed
6. dissolutionthe residue was then dissolved in acetone (25 mL)
7. additionAfter adding 2N HCl (2 mL) the s olution
8. stirringwas stirred at rt for 20 min
9. additionwas added
10. customThe solvents were removed
11. extractionthe residue was extracted with EtOAc
12. washThe organic layer was washed with water, and brine
13. customAfter drying over anhyd
14. filtrationMgSO4 the solution was filtered
15. customevaporated
16. customto yield the crude product (250 mg)
17. additionpoured on a column of silica gel
18. washElution with CH2Cl2