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標題: A short synthesis of (+)-narciclasine via a strategy derived from stereocontrolled epoxide formation and SnCl4-catalyzed arene-epoxide coupling
作者: Elango, S.
Yan, T.H.
關鍵字: asymmetric-synthesis
期刊/報告no:: Journal of Organic Chemistry, Volume 67, Issue 20, Page(s) 6954-6959.
摘要: A facile construction of the typical framework of narcissus alkaloids has been realized by virtue of the development of a practical route involving stereocontrolled epoxide formation and SnCl4-catalyzed arene-epoxide coupling. To achieve this goal, it proved to be necessary to devise a strategy that would enable chemical transformations to install an epoxy moiety in a congested environment. The successful preparation of a hindered epoxide from O-isopropylidene-protected 4-aminocyclo-hexenol required three steps consisting principally of controlled bromohydration and base-promoted closure and N-alkylation. It was found that a catalytic amount of SnCl4 not only maintained the catalytic cycle but also effected clean arylation to form a fused BC ring system. Several tactics that ultimately proved to be unsatisfactory are also discussed in an effort to set important boundary limits on arene-epoxide coupling. The requisite enantiopure 4-aminocyclohexenol was available via an asymmetric cycloaddition of diene to camphor-based chloronitroso. The total synthesis of (+)-narciclasine was realized in nine steps with an overall yield of 19%.
ISSN: 0022-3263
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