The IrelandâClaisen rearrangement of the lactate 8, prepared from the InhoffenâLythgoe diol 5, followed by iodolactonisation allowed easy access to the CâD-ring fragment 4, from which a novel convergent synthesis of (23S,25R)-1α,25-dihydroxyvitamin D3 26,23-lactone 1 has been accomplished via coupling with the A-ring fragment 3.
从Inhoffen-Lythgoe二醇5制备的
乳酸酯8通过Ireland-Claisen重排,随后经
碘代内酯化反应可以便捷地得到C-D环片段4。该片段与A环片段3偶联,完成了(23S,25R)-1α,25-二羟基
维生素D3-26,23-内酯1的一种新的收敛性合成。