Biomimetic Cyclization of Epoxide Precursors of Indole Mono-, Sesqui- and Diterpene Alkaloids by Lewis Acids
作者:Tetsuya ISAKA、Morifumi HASEGAWA、Hiroaki TOSHIMA
DOI:10.1271/bbb.110511
日期:2011.11.23
Cyclization of the synthesized epoxide precursors of indole mono-, sesqui- and diterpene alkaloids was performed to elucidate the mechanism for biomimetic cationic cyclization to polycyclic structures. 3-(6,7-Epoxygeranyl)indole (11), 3-(10,11-epoxyfarnesyl)indole (2) and 3-(14,15-epoxygeranylgeranyl)indole (3) were respectively synthesized from geraniol, farnesol and geranylgeraniol in 6 or 7 steps
进行吲哚单,倍半萜和二萜生物碱的合成环氧化物前体的环化,以阐明将仿生阳离子环化为多环结构的机理。分别由香叶醇,法呢醇和香叶基香叶醇合成3-(6,7-环氧香叶基)吲哚(11),3-(10,11-环氧法尼基)吲哚(2)和3-(14,15-环氧香叶基香叶基)吲哚(3)。分6步或7步。四个路易斯酸(MeAlCl(2),BF(3)·OEt(2),TiCl(4)和SnCl(4))用于合成环氧化物前体的仿生环化。色谱分离后,分离出环化产物(一种产物来自11种,两种产物来自2种,三种产物来自3种)。使用NMR(COSY,HSQC,HMBC,NOESY等)和HRMS分析确定其结构。结果表明仿生环化产生了类似于天然吲哚萜烯生物碱的新的多环化合物。我们得出结论,当使用路易斯酸时,阳离子中间体的稳定性应确定通过仿生环化形成产物的偏好。