| 摘要 |
<p>NEW MATERIAL:A compound of formula I (R1 is H, hydroxyl-protecting group; R2 and R3 incorporate to represent =O or X). EXAMPLE:The compound of formula Ia. USE:A synthetic intermediate of 25-hydroxycholesterol which is readily led to vitamin D3 analogues. It can be produced from readily available lithocholic acid through simple processes. PREPARATION:For example, lithocholic acid of formula II is used as a starting compound and the objective compound is obtained in accordance with the reaction equations.</p> |
