Ammonia → 3a,7ss-Dihydroxycholansaure

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A mixture of 100 g of 3α-hydroxy-7-keto-cholanic acid, 1000 ml of tetrahydrofuran and 30 ml of methanol was stirred until dissolution occured and the solution was cooled to -32° C. Then, 1000 ml of liquid ammonia were added thereto all at once and then 10 g of lithium in small particles were added thereto at -32° C. over 45 to 60 minutes. 100 ml of methanol were added to the mixture over 15 minutes and the ammonia was evaporated by placing the mixture in a water bath at 30° C. for one hour. 400 ml of demineralized water were added all at once to the reaction mixture which was then adjusted to a pH of ≃2 by addition of 200 ml of 22° Be hydrochloric acid. The mixture was extracted four times with 200 ml of ethyl acetate and the organic phase was washed with demineralized water and evaporated to dryness of 60° C. under reduced pressure. The residue was taken up 3 times with 100 ml of ethyl acetate and the organic phase was evaporated to dryness at 70° C. under reduced pressure to obtain 104 g of crystalline crude 3α,7β-dihydroxy-cholanic acid with a specific rotation of [α]D20 =+50°±1° (c=1% in ethanol). Thin layer chromatograpy showed the raw product contained about 8% of chenodesoxycholic acid (3α,7α-dihydroxy-5β-cholanic acid).

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