"Naked" Lithium Cation: Strongly Activated Metal Cations Facilitated by Carborane Anions
"Naked" Lithium Cation: Strongly Activated Metal Cations Facilitated by Carborane Anions
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DOI：
10.1021/acs.joc.6b02677
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发表时间：
2017-02-17
影响因子：
3.6
通讯作者：
Uchiyama, Masanobu
中科院分区：
文献类型：
--
作者：
Kitazawa, Yu;Takita, Ryo;Uchiyama, Masanobu
实验和光谱研究揭示了“裸”锂阳离子与非常弱的配位阴离子（包括碳硼烷阴离子）的前所未有的反应性。超活化锂离子具有极大增强的刘易斯酸性，并介导了各种有机反应，如羰基-烯反应、未活化芳烃的NBS-溴化反应和Friedel-Crafts烷基化反应，这些反应是常规锂盐所不能促进的。抗衡阴离子的化学稳定性也在强活化锂阳离子的化学中起重要作用。
Experimental and spectroscopic studies revealed unprecedented reactivity of a "naked" lithium cation with very weakly coordinating anions, including carborane anions. The superactivated lithium cation has greatly enhanced Lewis acidic character and mediates various organic reactions such as carbonyl-ene reaction, NBS-bromination of unactivated aromatics, and Friedel-Crafts alkylation, which are not promoted by conventional lithium salts. Chemical robustness of the counteranion also plays an important role in the chemistry of the strongly activated lithium cation.