反应详情

To a solution of dihydrocholesterol (5.0 g, 12.9 mmol, Aldrich), phthalimide (2.0 g, 13.6 mmol, Aldrich), and triphenylphosphine (3.8 g, 13.6 mmol, Aldrich) in THF (20 ml, Aldrich) stirred at 0° C. under a nitrogen atmosphere was added dropwise diethylazodicarboxylate (2.3 ml, 14.5 mmol, Aldrich). Upon the completion of addition the reaction mixture was allowed to warm to ambient temperature and stirred overnight. The reaction mixture was concentrated in vacuo to a residue. This residue was dissolved in 50 ml hexane/ethyl acetate 95/5 and a precipitate formed. The mixture was filtered. The filtrate was concentrated to dryness in vacuo, dissolved in 25 ml of hexane/ethyl acetate 95/5 and chromatographed on 200 g silica gel (eluent 2 L hexane/ethyl acetate 95/5 then 1 L hexane/ethyl acetate 90/10). A 76% yield of the desired 3-phthalimidocholestane (5.43 g) was obtained.

1. additionUpon the completion of addition the reaction mixture
2. concentrationThe reaction mixture was concentrated in vacuo to a residue
3. dissolutionThis residue was dissolved in 50 ml hexane/ethyl acetate 95/5
4. customa precipitate formed
5. filtrationThe mixture was filtered
6. concentrationThe filtrate was concentrated to dryness in vacuo
7. dissolutiondissolved in 25 ml of hexane/ethyl acetate 95/5
8. customchromatographed on 200 g silica gel (eluent 2 L hexane/ethyl acetate 95/5