C-24 stereochemistry of marine Sterols: (22E)-24-Ethyl-24-methylcholesta-5,22-dien-3b-oβl and 24-Ethyl-24-methylcholest-5-en-3β-ol
作者:Shizue Echigo、Leonardo Castellanos、Carmenza Duque、Hidehiro Uekusa、Noriyuki Hara、Yoshinori Fujimoto
DOI:10.1590/s0103-50532011000500026
日期:——
and (24S)-samples that were synthesized in routes involving the orthoester Claisen rearrangement of Δ23-22-allylic alcohols. This is the first synthetic study where the Claisen rearrangement is used to introduce a C-24 quaternary center in a stereospecific manner with acceptable yield. X-ray analysis of 1 confirmed these stereochemical assignments.
(22E)-24-乙基-24-甲基胆甾5,22-dien-3β-ol(1)和24-乙基-24-甲基胆甾-5-en-3β-ol(2)的C-24构型,分离自哥伦比亚加勒比海海绵Topsentia ophiraphidites的NMR数据与立体定义的(24R)和(24S)样品的NMR数据进行比较,分别确定其为R和S,这些样品在涉及Δ23的原酸酯克莱森重排的路线中合成-22-烯丙醇。这是第一项综合研究,其中使用克莱森重排以立体特异性方式以可接受的产率引入C-24四元中心。X射线分析1证实了这些立体化学分配。