On the Absolute Configurational Stability of Bromonium and Chloronium Ions
On the Absolute Configurational Stability of Bromonium and Chloronium Ions
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DOI：
10.1021/ja909965h
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发表时间：
2010-02-03
影响因子：
15
通讯作者：
Hoover, Andrew J.
中科院分区：
文献类型：
--
作者：
Denmark, Scott E.;Burk, Matthew T.;Hoover, Andrew J.
卤离子是烯烃卤代和卤代官能化反应的重要中间体。虽然这些主力反应已被广泛研究的机械和综合利用，缺乏对映体选择性的变体是惊人的。卤离子的可逆形成和烯烃-烯烃的转移是发展催化的对映体选择性卤官能化反应的核心问题。在这份报告中，构型定义和对映体富集溴和氯离子产生（对映体富集前体的溶剂分解），并显示被拦截分子间高对映体和非对映体特异性的各种亲核试剂。最重要的是，在烯烃的存在下，捕获的立体特异性没有被显著侵蚀。
Halonium ions have long been established as the critical intermediates in halogenation and halo functionalization of alkenes. Although these workhorse reactions have been extensively studied mechanistically and employed synthetically, the paucity of enantioselective variants is striking. A central problem in the development of catalytic enantioselective halofunctionalizations is the reversible formation of halonium ions and the facile olefin-to-olefin transfer. In this report, configurationally defined and enantiomerically enriched bromonium and chloronium ions are generated (by solvolysis of enantiomerically enriched precursors) and shown to be intercepted intermolecularly with high enantio- and diastereospecificity by various nucleophiles. Most importantly, the stereospecificity of capture is not significantly eroded in the presence of olefins.