Studies dealing with thionium ion promoted mannich cyclization reactions.
Studies dealing with thionium ion promoted mannich cyclization reactions.
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DOI：
10.1002/chin.200016044
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发表时间：
2000-01
期刊：
影响因子：
--
通讯作者：
A. Padwa;A. Waterson
中科院分区：
文献类型：
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作者：
A. Padwa;A. Waterson
用二甲基（甲硫基）锍四氟硼酸盐（DMTSF）处理几种酰胺基取代的硫代缩醛产生合成有用的硫鎓离子，这些硫鎓离子被相邻的氮原子拦截，得到五元和六元烷硫基取代的内酰胺作为瞬态中间体。烷硫基取代的内酰胺与DMTSF的进一步反应产生N-酰基异丙基离子，其与束缚的芳环进行环化以产生氮杂多环环系统。当使用具有简单烯系链的酰胺基硫代缩醛时，发生相关的环化序列。整个过程代表了一种有效的一锅法对各种含氮环系统。采用环合反应合成刺桐生物碱家族的核心骨架。
Treatment of several amido-substituted thioacetals with dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) produces synthetically useful thionium ions that are intercepted by the adjacent nitrogen atom to afford both five- and six-membered alkylthio-substituted lactams as transient intermediates. Further reaction of the alkylthio-substituted lactam with DMTSF generates an N-acyliminium ion, which undergoes cyclization with the tethered aromatic ring to produce an azapolycyclic ring system. Related cyclization sequences occur when amido thioacetals possessing simple olefinic tethers were used. The overall procedure represents an efficient one-pot approach toward various nitrogen-containing ring systems. The cyclization reaction was employed for a synthesis of the core skeleton of the erythrina alkaloid family.