著者

Tetsuya ISAKA Morifumi HASEGAWA Hiroaki TOSHIMA

出版者

Japan Society for Bioscience, Biotechnology, and Agrochemistry

雑誌

Bioscience, Biotechnology, and Biochemistry (ISSN:09168451)

巻号頁・発行日

pp.1109292684, (Released:2011-11-07)

参考文献数

28

被引用文献数

20

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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. Four Lewis acids (MeAlCl2, BF3·OEt2, TiCl4 and SnCl4) were applied for biomimetic cyclization of the synthesized epoxide precursors. The cyclization products (one product from 11, four products from 2, and three products from 3) were isolated after separation by chromatography. Their structures were determined by using NMR (COSY, HSQC, HMBC, NOESY, etc.) and HRMS analyses. The results show that biomimetic cyclization gave new polycyclic compounds similar to natural indole terpene alkaloids. We conclude that the stability of cation intermediates should determine the preference for product formation by biomimetic cyclization when using a Lewis acid.