Total Synthesis of (±)-Methyl Atis-16-en-19-oate via Homoallyl−Homoallyl Radical Rearrangement
作者:Masahiro Toyota、Toshihiro Wada、Keiichiro Fukumoto、Masataka Ihara
DOI:10.1021/ja9739042
日期:1998.5.1
Total synthesis of (±)-methyl atis-16-en-19-oate (5c), a tetracyclic diterpenoid possessing a bicyclo[2.2.2]octane ring system, was accomplished. Intramolecular Diels−Alder reaction of tetraene 14 was employed in a construction of kaurene skeleton 13. The pivotal step involved a homoallyl−homoallyl radical rearrangement process of (±)-methyl 12-hydroxykaur-16-en-19-oate monothioimidazolide 12, which
完成了 (±)-methyl atis-16-en-19-oate (5c) 的全合成,这是一种具有双环 [2.2.2] 辛烷环系统的四环二萜。四烯14的分子内Diels-Alder反应用于构建贝壳杉烯骨架13。关键步骤涉及(±)-甲基12-羟基kaur-16-en-19-oate单硫咪唑化物12的高烯丙基-高烯丙基重排过程,其中导致 5c 的良率很高。有趣的是,在双(乙二醇)中,在 KOH 存在下,在 200 °C 下用一水合肼处理 12-oxo-kaur-16-en-19-oate 30 导致环丙烷化,直接提供 trachyloban-19-oic酸 (4b),连同 kaur-16-en-19-oic 酸 (6b)。