Nitrone dipolar cycloaddition routes to piperidines and indolizidines. Part 9.Part 8. See Ref. 22. Formal synthesis of (–)-pinidine and total synthesis of (–)-histrionicotoxin, (+)-histrionicotoxin and (–)-histrionicotoxin 235AThis manuscript is dedicated to the sixtieth birthday of Professor L. Tietze.
作者:Edwin C. Davison、Martin E. Fox、Andrew B. Holmes、Stephen D. Roughley、Catherine J. Smith、Geoffrey M. Williams、John E. Davies、Paul R. Raithby、Joseph P. Adams、Ian T. Forbes、Neil J. Press、Mervyn J. Thompson
DOI:10.1039/b200328g
日期:2002.6.7
for the enantioselective synthesis of the cyclic nitrones 36 and 44. We have demonstrated the use of a novel nitrone protection strategy by cycloaddition of styrene to the cyclic nitrone 44 in the synthesis of the spirocyclic core of the histrionicotoxin family of alkaloids. Deprotection by dipolar cycloreversion of the styrene adduct (the bicyclic isoxazolidine 39) and in situ intramolecular dipolar
分子内 羟胺--炔烃 环化用于环状硝酮36和44的对映选择性合成。我们已经证明了新的硝酮保护策略的使用环加成 的 苯乙烯环硫酮44的环硫毒素家族的螺环核心的合成中生物碱。偶极脱保护环回 的 苯乙烯 加合物(双环 异恶唑烷 39)和原位分子内偶极环加成(Z)-α,β-不饱和侧链的腈与相应的(Z)-烯炔36相比,中间体硝基50上的异恶唑烷51的收率高,区域选择性出人意料。该方法适合于合成三环核心结构的对映异构体51和62,它们可以分别通过常见的中间体(例如53和ent - 53)转化为天然构型。生物碱(-)-histrionicotoxin 1和(-)-histrionicotoxin 235A 65以及非天然(+)-histrionicotoxin 63。