Ethanol → Colestolone

Participants

Reaction Conditions

Reaction Steps

A mixture of 3β-benzoyloxy-14α,15α-epoxy-5α-cholest-7-ene (26, 12.0 g, 23.8 mmol), 95% ethanol (300 mL), and water (35 mL) was cooled to 5° C. in an ice water bath. To this solution was added, in portions of 5 mL, concentrated sulfuric acid (65.0 mL). After the addition (~5 min) the reaction mixture was heated under reflux for 22 h. Stirring must be effective to prevent clumping of the starting material. The clear reaction mixture was cooled to ambient temperature, then poured into ice (700 g). A sticky precipitate was formed (could not be filtered). The water phase was extracted three times with ethyl acetate (400, 200, and 200 mL). The combined ethyl acetate phase was washed with water, 5% sodium bicarbonate, and sodium chloride solution, and dried over sodium sulfate. Evaporation of the solvent gave a semisolid yellowish compound (14 g). The crude compound 27 was purified by flash chromatography (4.0×35 cm column) and eluted with ethyl acetate/hexane (1:3). Fractions containing product were combined and evaporated to give after crystallization from methanol/water pure product as fine needles 4.5 (47%). Mp, NMR, and IR data were in agreement with published data.

Provenance & Evidence