The optically active tetracyclic ketone 8 was converted into the pentacylic core 14 of the C-19 methyl substituted Na-H sarpagine and ajmaline alkaloids via a critical haloboration reaction. The ketone 14 was then employed in the total synthesis of 19(S),20(R)-dihydroperaksine-17-al (1) and 19(S),20(R)-dihydroperaksine (2). The key regioselective hydroboration and controlled oxidation–epimerization
通过关键的卤
硼化反应,光学活性四环
酮8被转化为C-19
甲基取代的Na - H沙帕津和
阿马林生物碱的五环核14 。然后将
酮14用于19( S ),20( R )-二
氢帕拉克辛-17-al( 1 )和19( S ),20( R )-二
氢帕拉克辛( 2 )的全合成。该方法中开发的关键区域选择性
硼氢化和受控
氧化-差向异构序列应提供一种通用方法来功能化
阿马林相关
吲哚生物碱中的 C(20)-C(21) 双键。