| 摘要 |
<p>PURPOSE:To obtain in high efficiency the title derivative useful as an intermediate for e.g. 1a,25-dihydroxy-20-oxa-21-norvitamin D3 by protecting the OH group at 17-site of a 17-hydroxytriene compound followed by enol acetylation, reduction etc. CONSTITUTION:The 17-site OH group of a compound of formula I is protected, followed by enol acetylation into a compound, which is then reduced into a compound of formula II (X is protecting group). This compound is then reacted with 4-phenyl-1,2,4-triazoline-3,5-dione into a compound of formula III. Thence, the 3-site OH group is protected and the 17-site group is deprotected and then protected again with a protective group inert to aluminum hydroxide etc., to form a compound of formula V (Y and Z are each protecting group), which is then treated with an epoxidizing reagent into a compound of formula V. Thence, the 3-site OH group of this compound is deprotected followed by reduction with e.g. aluminum hydroxide into a compound of formula VI. The OH groups at 1-and 3-sites of this compound are acetylated and the 17-site group is then deprotected into a compound of formula VII, which is then oxidized to obtain the objective compound of formula VIII.</p> |
