| 摘要 |
<p>PURPOSE:To obtain the titled compound useful as a calcium metabolic adjustor, by isomerizing a hydroxycholesta-5,7-diene protected by a lower alkoxy group thermally under irradiation of ultraviolet light. CONSTITUTION:A hydroxycholesta-5,7-diene of formula I (R1 and R2 are lower alkoxycarbonyl R3 and R4 are H or lower alkoxycarbonyloxy) is isomerized thermally under irradiation of ultraviolet light to give a mixture of an active vitamin D3 derivative of formula II in which the hydroxyl groups are protected with the unreacted hydroxycholesta-5, 7-diene of formula I. The unreacted compound of formula I and the compound of formula II are then separated from the resultant mixture, and the unreacted compound of formula I is circulated for reuse. The protecting groups in the compound of formula II are then removed to afford the titled compound of formula III (R3' and R4' are H or OH).</p> |
