反应详情

The enol acetate of Example 896 is brominated and dehydrobrominated by the method described in Example 13. The crude product is then dissolved in methylene chloride and is added at -78° C. to a methylene chloride solution containing about seven molar equivalents of boron tribromide. After one hour at -78° C. the solution is allowed to warm to room temperature and is then kept at ambient temperatures for a total of 18 hours. The mixture is poured into water and extracted with ether. The organic phase is washed with saturated saline solution, then water and is dried. Evaporation of solvents leaves subject product, which is purified by distillation. The combined organic phases are washed with ice cold 5% sodium hydroxide solution, ice cold 5% hydrochloric acid, and saturated sodium chloride solution, dried with anhydrous magnesium sulfate and taken to dryness. Distillation gives a pale yellow oil; λ max 5.85 μ (carbonyl group).

1. customis then kept at ambient temperatures for a total of 18 hours
2. extractionextracted with ether
3. washThe organic phase is washed with saturated saline solution
4. dry with materialwater and is dried
5. customEvaporation of solvents
6. customleaves
7. distillationis purified by distillation
8. washThe combined organic phases are washed with ice cold 5% sodium hydroxide solution, ice cold 5% hydrochloric acid, and saturated sodium chloride solution
9. dry with materialdried with anhydrous magnesium sulfate
10. distillationDistillation
11. customgives a pale yellow oil