Catalytic, stereospecific syn-dichlorination of alkenes.
Catalytic, stereospecific syn-dichlorination of alkenes.
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DOI：
10.1038/nchem.2141
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发表时间：
2014-02
期刊：
影响因子：
21.8
通讯作者：
Denmark SE
中科院分区：
文献类型：
--
作者：
Cresswell AJ;Eey ST;Denmark SE
作为已知的一些最古老的有机化学反应，元素卤素（例如溴和氯）与烯烃的离子加成是立体定向反应的典型例子，通常通过反加成产生邻位二卤化物。虽然对映选择性变体的发明是一个持续的挑战，但推翻这些转化的内在反非对映特异性的能力在很大程度上也是一个尚未解决的问题。在本文中，我们描述了使用基于氧化还原活性主族元素（即硒）的基团转移催化剂进行烯烃的第一个催化、同立体有择二氯化。因此，以二苯基二硒化物 (PhSeSePh) (5 mol%) 作为预催化剂，以苄基三乙基氯化铵 (BnEt3NCl) 作为氯化物源，以 N-氟吡啶鎓盐作为氧化剂，多种官能化环状和无环 1,2-二取代烯烃，包括简单的烯丙醇，可提供具有精细立体控制的顺二氯化物。该方法有望在简化多氯天然产物（例如氯磺脂）的合成中得到应用。
As some of the oldest organic chemical reactions known, the ionic additions of elemental halogens such as bromine and chlorine to alkenes are prototypical examples of stereospecific reactions, typically delivering vicinal dihalides resulting from anti-addition. Whilst the invention of enantioselective variants is an ongoing challenge, the ability to overturn the intrinsic anti-diastereospecificity of these transformations is also a largely unsolved problem. In this Article, we describe the first catalytic, syn-stereospecific dichlorination of alkenes, employing a group transfer catalyst based on a redox-active main group element (i.e., selenium). Thus, with diphenyl diselenide (PhSeSePh) (5 mol %) as the pre-catalyst, benzyltriethylammonium chloride (BnEt3NCl) as the chloride source, and an N-fluoropyridinium salt as the oxidant, a wide variety of functionalized cyclic and acyclic 1,2-disubstituted alkenes, including simple allylic alcohols, deliver syn-dichlorides with exquisite stereocontrol. This methodology is expected to find applications in streamlining the synthesis of polychlorinated natural products such as the chlorosulfolipids.