| 摘要 |
PURPOSE:A 3-oxo-4-cholic acid derivative is treated with acetic anhydrid or the like, then the product is reduced to enable simple and industrially advantageous production of the title compound which is used as a synthetic intermediate of vitamin D analogues. CONSTITUTION:A 3-oxo-4-cholic acid of formula I (R is lower alkyl) is treated with acetic anhydride or isopropenyl acetate in the presence of an acid catalyst such as p-toluenesulfonic acid, preferably at about 80 deg.C to prepare 3-acetoxy-3,5- diene-cholanic acid derivative of formula II. Then, the product is reduced using, e.g., sodium borohydride to give the objective compound of formula III.
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