The chemical transformations of α-santonin (1), a C-6 lactonized eudesmanolide, into C-8 lactonized eudesmanolides, i.e., yomogin (2) and four diastereoisomers of dihydrograveolide (36-39), are described. Transposition of 6, 13-olide into 8, 13-olide in eudesmanolides was investigated. Allylic oxidation of the trienone (12) with tert-butyl chromate gave 3, 8-dioxotriene (20) and 3, 6-dioxotriene (22). Reductive lactonization of 20 gave 11α- and 11β-methyl cis-lactones (30 and 31). Yomogin (2) was synthesized from the cis-lactones (32 and 33) by phenylselenenylation and deselenoxylation procedures. Catalytic reduction of 30 and 31 gave diastereoisomers of dihydrograveolide (36-39).
α-
山道年(1)是一种C-6内酯化的桉叶烷内酯,本文描述了其转化为C-8内酯化的桉叶烷内酯,即扁
蒿素(2)和二氢墓亭内酯(36-39)的四种立体异构体的过程。研究了桉叶烷内酯中6,13-内酯向8,13-内酯的转移。
三烯酮(12)与叔丁基
铬酸酯的烯丙位氧化得到3,8-二氧
三烯(20)和3,6-二氧
三烯(22)。20的部分还原内酯化得到11α-和11β-甲基顺式内酯(30和31)。通过苯基
硒化和去
硒氧化的方法,从顺式内酯(32和33)合成了扁
蒿素(2)。30和31的催化还原得到二氢墓亭内酯(36-39)的立体异构体。