反应详情

To a cold (-78° C.) solution of LDA, from 0.2 mol of n-BuLi, 29 ml (0.207 mol) of diisopropylamine and 200 ml of dimethoxyethane was added a solution of 23.4 g (0.1 mol) of product of Example 34 in 500 ml of dimethoxyethane in 5 minutes. The reaction mixture turned red and precipitate formed and made magnetic stirring difficult. The reaction flask was shaken by hand for 5 minutes and the reaction mixture was treated with 25 ml (0.2 mol) of ethyl trifluoroacetate at once. The precipitate gradually dissolved. The reaction mixture was stirred and warmed to room temperature in 2 hours, then was poured into 500 ml of ice water. The mixture was extracted with ether. The aqueous layer was acidified with concentrated HCl to give a white solid. The ether layer was extracted with 10% K2CO3 (200 ml) and the basic extract was acidified with concentrated HCl to give additional solid. The combined solid was dissolved in 10% K2CO3 and washed with ether. The aqueous solution was acidified with concentrated HCl and filtered. The solid was recrystallized from chloroform-acetone to remove 8.0 g of a solid. The mother liquor was concentrated and the residue was kugelrohr distilled at 133 Pa (pot temperature 120° C.) to give an oil-solid mixture which was crystallized from hexane at low temperature to give 4.8 g (15%) of product; mp 23°-24.5° C. This material melted upon standing, nD25 1.4343.

1. customprecipitate formed
2. dissolutionThe precipitate gradually dissolved
3. stirringThe reaction mixture was stirred
4. extractionThe mixture was extracted with ether
5. customto give a white solid
6. extractionThe ether layer was extracted with 10% K2CO3 (200 ml)
7. extractionthe basic extract
8. customto give additional solid
9. washwashed with ether
10. filtrationfiltered
11. customThe solid was recrystallized from chloroform-acetone
12. customto remove 8.0 g of a solid
13. concentrationThe mother liquor was concentrated
14. distillationthe residue was kugelrohr distilled at 133 Pa (pot temperature 120° C.)
15. customto give an oil-solid mixture which
16. customwas crystallized from hexane at low temperature