Nitrone Cycloadditions of 1,2-Cyclohexadiene.
Nitrone Cycloadditions of 1,2-Cyclohexadiene.
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DOI：
10.1021/jacs.5b13304
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发表时间：
2016-03-02
影响因子：
15
通讯作者：
Garg NK
中科院分区：
文献类型：
--
作者：
Barber JS;Styduhar ED;Pham HV;McMahon TC;Houk KN;Garg NK
我们报道了 1,2-环己二烯（一种很少被利用的应变丙二烯）的第一个 1,3-偶极环加成反应。 1,2-环己二烯在温和条件下原位生成，并用硝酮捕获，以合成有用的收率得到异恶唑烷产物。该反应以区域选择性发生并表现出显着的内切偏好，从而导致两个新键和两个立体中心的受控形成。逐步和协同反应路径的 DFT 计算用于合理化观察到的选择性。此外，硝酮环加合物的策略性操作证明了该方法对于组装带有多个杂环单元的化合物的实用性。这些研究展示了化学合成中传统上避免的反应中间体的利用。
We report the first 1,3-dipolar cycloadditions of 1,2-cyclohexadiene, a rarely exploited strained allene. 1,2-Cyclohexadiene is generated in situ under mild conditions and trapped with nitrones to give isoxazolidine products in synthetically useful yields. The reactions occur regioselectively and exhibit a notable endo preference, thus resulting in the controlled formation of two new bonds and two stereogenic centers. DFT calculations of stepwise and concerted reaction pathways are used to rationalize the observed selectivities. Moreover, the strategic manipulation of nitrone cycloadducts demonstrates the utility of this methodology for the assembly of compounds bearing multiple heterocyclic units. These studies showcase the exploitation of a traditionally avoided reactive intermediate in chemical synthesis.