Enantioselective cyclizations and cyclization cascades of samarium ketyl radicals
Enantioselective cyclizations and cyclization cascades of samarium ketyl radicals
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DOI：
10.1038/nchem.2841
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发表时间：
2017-12-01
期刊：
影响因子：
21.8
通讯作者：
Procter, David J.
中科院分区：
文献类型：
--
作者：
Kern, Nicolas;Plesniak, Mateusz P.;Procter, David J.
从简单的起始材料快速生成复杂的分子是合成中的一个关键挑战。对映选择性自由基环化级联具有在一个步骤中提供复杂的、密集堆积的、多环结构并控制三维形状的潜力。不幸的是，由于自由基的高反应性，以对映体控制的方式进行与自由基的反应仍然具有挑战性。对于使用经典试剂SmI2产生的自由基的反应，情况尤其如此。在这里，我们证明了对映选择性的SmI2介导的自由基环化和级联，利用一个简单的，可回收的手性配体可以将对称的酮酯复杂的碳环产品承载多个立体中心，高对映体和非对映体控制。计算研究已被用来探测的对映体选择性的起源。我们的研究表明，许多依赖于SmI2的过程可以通过设计合适的配体来实现对映选择性。
The rapid generation of molecular complexity from simple starting materials is a key challenge in synthesis. Enantioselective radical cyclization cascades have the potential to deliver complex, densely packed, polycyclic architectures, with control of three-dimensional shape, in one step. Unfortunately, carrying out reactions with radicals in an enantiocontrolled fashion remains challenging due to their high reactivity. This is particularly the case for reactions of radicals generated using the classical reagent, SmI2. Here, we demonstrate that enantioselective SmI2-mediated radical cyclizations and cascades that exploit a simple, recyclable chiral ligand can convert symmetrical ketoesters to complex carbocyclic products bearing multiple stereocentres with high enantio-and diastereocontrol. A computational study has been used to probe the origin of the enantioselectivity. Our studies suggest that many processes that rely on SmI2 can be rendered enantioselective by the design of suitable ligands.