ether of (S)-2-methylglycidol with lithium 4,4′-di-t-butylbiphenylide, addition of aldehyde 3 to the resulting β-lithioalkoxide, followed by acidic hydrolysis, yields the advanced (23S,25R)-calcitriol lactone intermediate 4 plus its 23R epimer (∼1:1, 69%).
(S)-2-甲基
缩水甘油的((1-甲基-1-甲氧基)乙基)醚与4,4'-二叔丁基
联苯锂的还原裂解,向所得β-
硫代醇盐中添加醛3,然后通过酸性
水解,得到高级的(23S,25R)-
骨化三醇内酯中间体4加上其23R差向异构体(〜1∶1,69 %)。