Acetic Acid → 5beta-Chol-9(11)-en-24-oic acid, 3alpha-hydroxy-12-oxo-, methyl ester, acetate

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Reaction Conditions

Reaction Steps

CrO3 (17.0 g, 170 mmol) was added to a solution of compound 1.8a (17 g, 39.5 mmol) in AcOH (270 mL). The resulting mixture was heated at 50° C. for 24-36 h. Upon complete disappearance of the starting material by TLC, the solvent was evaporated under vacuum and the crude material was dissolved in ethyl acetate (400 mL) and water (200 mL). The two phases were separated and the organic layer was washed twice with water (2×100 mL) and then once with saturated brine solution (100 mL). The organic phase was dried over anhydrous Na2SO4 (40 g) and filtered. The filtrate was concentrated under vacuum and the resulting solid was purified by column chromatography [49 mm (W)×600 mm (L), 60-120 mesh silica, 120 g], eluting with ethyl acetate/hexane (1:5) [10 mL fractions, 3 mL/min elution, monitored by TLC and detected with UV light (254 nm) lamp]. The product-containing fractions were combined and concentrated under vacuum to afford compound 1.9a (8.8 g, 50% yield) as a white solid.

Provenance & Evidence