Metalloradical activation of carbonyl azides for enantioselective radical aziridination.
Metalloradical activation of carbonyl azides for enantioselective radical aziridination.
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DOI：
10.1016/j.chempr.2021.03.001
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发表时间：
2021-04-08
期刊：
影响因子：
23.5
通讯作者：
Zhang XP
中科院分区：
文献类型：
--
作者：
Riart-Ferrer X;Sang P;Tao J;Xu H;Jin LM;Lu H;Cui X;Wojtas L;Zhang XP
有机叠氮化物由于其易于制备和生成良性N2作为催化烯烃叠氮化反应的唯一副产物而被越来越多地用作氮源。在常见的有机叠氮化物中，羰基叠氮化物以前没有被证明是分子间烯烃叠氮化的有效氮源，尽管n -羰基叠氮化物在合成上很有用。作为金属催化的一种新应用，我们开发了一种能在室温下有效利用羰基叠氮化物TrocN3进行烯烃高度不对称叠氮化反应的催化体系。所得到的对映体富集的n - trocaziridine已被证明是有价值的手性合成物，可用于立体选择性合成其他手性叠氮嘧啶和各种手性胺。Co（II）基金属体系具有独特的步进自由基机制，为烯烃与有机叠氮化物不对称合成手性叠氮醚提供了一种通用的方法。羰基叠氮化物TrocN3（2,2,2-三氯乙氧羰基叠氮化物）是通过Co（II）基金属催化（MRC）进行自由基烯烃叠氮化反应的有效氮自由基前体。d2对称手性氨基卟啉3,5-迪布-青卟啉的钴（II）配合物是一种有效的催化剂，可在室温下激活TrocN3合成各种苯乙烯衍生物，以高收率和优异的对映选择性制备手性n -羰基aziridines。新的Co（II）基催化体系甚至可以使缺乏电子的烯烃（如甲基丙烯酸酯和乙基丙烯酸酯）实现不对称叠氮化。生成的n -Troc-aziridine除了可以方便地去除Troc基生成无保护的aziridine外，还可以被不同类型的亲核试剂有效地打开，从而产生一系列具有良好立体特异性的手性胺衍生物。一些计算和实验证据支持潜在的Co（II）催化烯烃叠氮化的逐步自由基机制。这是采用羰基叠氮化物作为氮源的不对称分子间烯烃叠氮化的第一个例子。以羰基叠氮化物TrocN3为氮源，建立了一种Co（II）基体系，用于烯烃的对映选择性自由基叠氮化。该催化体系在室温下，在中性和非氧化条件下工作，既适用于芳烃，也适用于缺电子烯烃，并能以高收率合成n-羰基偶氮吡啶，具有优异的对映选择性。富含对映体的n -羰基叠氮嘧啶已被证明是立体选择性有机合成的有价值的中间体。研究表明，Co（II）催化的叠氮化反应是通过逐步自由基机制进行的。
Organic azides have been increasingly employed as nitrogen sources for catalytic olefine aziridination due to their ease of preparation and generation of benign N2 as the only byproduct. Among common organic azides, carbonyl azides have not been previously demonstrated as effective nitrogen sources for intermolecular olefin aziridination despite the synthetic utilities of N-carbonyl aziridines. As a new application of metalloradical catalysis, we have developed a catalytic system that can effectively employ the carbonyl azide TrocN3 for highly asymmetric aziridination of alkenes at room temperature. The resulting enantioenriched N-Trocaziridines have been shown as valuable chiral synthons for stereoselective synthesis of other chiral aziridines and various chiral amines. The Co(II)-based metalloradical system, which proceeds with distinctive stepwise radical mechanism, may provide a general method for asymmetric synthesis of chiral aziridines from alkenes with organic azides. The carbonyl azide TrocN3 (2,2,2-trichloroethoxycarbonyl azide) is a potent nitrogen radical precursor for radical olefin aziridination via Co(II)-based metalloradical catalysis (MRC). The cobalt(II) complex of D2-symmetric chiral amidoporphyrin 3,5-DitBu-QingPhyrin proves to be an efficient catalyst that can activate TrocN3 at room temperature to aziridinate various styrene derivatives, providing chiral N-carbonyl aziridines in high yields with excellent enantioselectivities. The new Co(II)-based catalytic system can even enable asymmetric aziridination of electron-deficient alkenes, such as methyl and ethyl acrylates. In addition to facile removal of Troc group for generation of unprotected aziridines, the resulting N-Troc-aziridines can be effectively opened by different types of nucleophiles to afford a series of chiral amine derivatives with excellent stereospecificity. Several lines of computational and experimental evidence support the underlying stepwise radical mechanism for Co(II)-catalyzed olefin aziridination. This represents the first example of asymmetric intermolecular olefin aziridination that employs carbonyl azides as the nitrogen source. A Co(II)-based system has been developed for enantioselective radical aziridination of alkenes using the carbonyl azide TrocN3 as the nitrogen source. The catalytic system, which operates at room temperature under neutral and nonoxidative conditions, is applicable to both aromatic and electron-deficient olefins and enables the synthesis of N-carbonyl aziridines in high yields with excellent enantioselectivities. The enantioenriched N-carbonyl aziridines have been demonstrated as valuable intermediates for stereoselective organic synthesis. The Co(II)-catalyzed aziridination has been shown to proceed with stepwise radical mechanism.
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影响因子：
15
作者：
Gansaeuer, Andreas;Fan, Chun-An;Keil, Jutta
通讯作者：
Keil, Jutta
影响因子：
3.6
作者：
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影响因子：
2.8
作者：
Fantauzzi, Simone;Gallo, Emma;Cenini, Sergio
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影响因子：
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作者：
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影响因子：
16.6
作者：
Gansaeuer, Andreas;Hildebrandt, Sven;Flowers, Robert A., II
通讯作者：
Flowers, Robert A., II