An electron-catalyzed cope cyclization. The structure of the 2,5-dicyano-1,5-hexadiene radical anion in the gas phase.
An electron-catalyzed cope cyclization. The structure of the 2,5-dicyano-1,5-hexadiene radical anion in the gas phase.
复制标题
电子催化的上环化。
DOI：
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发表时间：
2003
影响因子：
15
通讯作者：
P. Wenthold
中科院分区：
文献类型：
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作者：
Loubna A. Hammad;P. Wenthold
2，5-二氰基-1，5-己二烯自由基阴离子在流动余辉三重四极装置中发生了Cope环化反应。利用化学反应活性确定了2，5-二氰基-1，5-己二烯阴离子的环状结构。离子与二氧化碳和CS2通过加成反应，而闭壳分子的自由基阴离子，如富马腈，不与这些试剂反应。该离子表现出远离子的反应性特征，因为它顺序地添加二氧化碳和NO或NO2。它通过在m/z 135处形成对应于加成之后失去HCN的产物来与NO反应。产物离子在m/z135处的反应性和CID谱与草酸根离子的反应活性和CID谱一致，后者需要一个环状前驱体离子。生成丙烯腈和2，6-二氰基-1，6-庚二烯自由基阴离子的尝试没有成功，这为2，5-二氰基-1，5-己二烯自由基阴离子的线性结构作为稳定结构提供了额外的证据。2，5-二氰基-1，5-己二烯自由基阴离子的环化反应是电子催化环化反应的第一例。
The radical anion of 2,5-dicyano-1,5-hexadiene is shown to undergo Cope cyclization in a flowing afterglow-triple quadrupole apparatus. The cyclic structure of the 2,5-dicyano-1,5-hexadiene radical anion was established by using chemical reactivity. The ion reacts with CO2 and CS2 by addition, whereas the radical anions of closed-shell molecules such as fumaronitrile do not react with these reagents. The ion exhibits reactivity characteristic of a distonic ion in that it sequentially adds CO2 and NO or NO2. It reacts with NO by forming a product at m/z 135 corresponding to addition followed by loss of HCN. The reactivity and CID spectrum of the product ion at m/z 135 agrees with that of oximate ion, which requires a cyclic precursor ion. Attempts to generate radical anions of acrylonitrile and 2,6-dicyano-1,6-heptadiene were unsuccessful, providing additional evidence against a linear structure as a stable structure for 2,5-dicyano-1,5-hexadiene radical anion. The cyclization of the radical anion of the 2,5-dicyano-1,5-hexadiene is the first example of an electron-catalyzed Cope cyclization.