Synthesis of Bridged Azabicycles from Pyridines and Pyrrole by a Diallylboration - Ring Closing Metathesis Sequence
作者:Nikolai Yu. Kuznetsov、Viktor N. Khrustalev、Ivan A. Godovikov、Yuri N. Bubnov
DOI:10.1002/ejoc.200500560
日期:2006.1
A straightforward method for the preparation of bridged azabicycles by a diallylboration–ring closing metathesis (RCM) sequence was elaborated. The precursors for the metathesis reaction were prepared by reductive trans-diallylation of aromatic heterocycles such as pyridines, isoquinoline and pyrrole with triallylborane and an alcohol. Heating of the trans isomers with one equivalent of triallylborane
详细阐述了通过二烯丙基硼化-闭环复分解(RCM)序列制备桥连氮杂双环的简单方法。复分解反应的前体是通过芳香杂环如吡啶、异喹啉和吡咯与三烯丙基硼烷和醇的还原转二烯丙基化反应制备的。用一当量的三烯丙基硼烷加热反式异构体,可以得到相应的顺式异构体——或(在吡咯的情况下)顺式和反式异构体的混合物。胺官能团的 Boc 保护提供了具有烯丙基轴向取向的 RCM 反应的前体。该阶段的化学产率非常好,反应所需的格鲁布斯催化剂量不超过2.5 mol-%(第一代催化剂)或3.7 mol-%(第二代催化剂)。氮杂双环[4.2. 1]壬烯,从吡咯获得,是毒蕈胺的关键结构基序。通过单晶X射线分析研究了cis-1,3-diallyl-1,2,3,4-四氢异喹啉和氮杂双环[4.3.1]癸二烯的结构。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)