Lithium → Cholan-24-oic acid, 3-oxo-, methyl ester, (5alpha)-

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Reaction Steps

Into a solution of 3-oxo-4-cholenic acid methyl ester 3002 (13.0 g, 23.68 mmol) in dry ether (50 ml) was added distilled liquid ammonia (70 ml) at -78° C. Lithium (1.0 g, 144.1 mmol) was added in small portions until a blue coloration persisted for 10 minutes, after which the solution was quenched with solid NH4Cl (50 g). Ammonia was evaporated, and the resulting residue was partitioned between water (100 ml) and ether (150 ml). The aqueous solution was extracted further with ether (3×50 ml). The combined extracts were washed with brine (1×70 ml), dried (MgSO4), filtered and concentrated in vacuo to get the crude product. Flash chromatography of the crude product in silica gel using ethyl acetate:hexane (2:8) gave pure 3-oxo-5α-cholanic acid methyl ester 3003 (3.85 g, 29%). 1H NMR (400 MHz, CDCl3) δ: 0.69 (3 H, s, 18-CH 0.91 (3H, d, 21-CH3), 1.02 (3 H, s, 19-CH3) and 3.66 (3 H, s, CO2CH3).

Provenance & Evidence