反应详情

Compound 20a (39.96 g, 165.7 mmol) was dissolved in dioxane (25 mL) and the solution added dropwise with stirring to 4 N HCl in dioxane (Aldrich, 250 mL). After 45 min, TLC analysis indicated complete deprotection. Volatiles were removed under reduced pressure, and the residue co-evaporated twice with MeOH (2×100 mL). Ether (300 mL) and MeOH (10 mL) were added to the brown, oily residue and the mixture stirred overnight at room temperature resulting in the precipitation of a semi-solid. Additional MeOH (15 mL) was added and stirring continued for 6 h, at which point a yellowish solid was collected by filtration. The product was washed with 5% MeOH in ether (50 mL) and ether (2×50 mL), and dried in vacuo to give compound 20b as a yellowish solid (22.60 g, 76% yield). Filtrates (including washings) were evaporated in vacuum to give additional 20b as a brown oil (7.82 g, 26% yield). Both fractions were pure enough for use in the synthesis of HCV protease inhibitors: [a]D25+38.2° (c 1.0, MeOH).

1. additionthe solution added dropwise
2. customVolatiles were removed under reduced pressure
3. additionEther (300 mL) and MeOH (10 mL) were added to the brown, oily residue
4. customresulting in the precipitation of a semi-solid
5. stirringstirring
6. waitcontinued for 6 h, at which point
7. filtrationa yellowish solid was collected by filtration
8. washThe product was washed with 5% MeOH in ether (50 mL) and ether (2×50 mL)
9. customdried in vacuo