Phthalimide → 3-Phthalimidocholestane

Participants

Reaction Steps

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.

Provenance & Evidence