Research News, May 25th, 2011
Iterative Dianion Relay Along the Ring: Formation of gem-Bis(trimethylsilyl) Cyclopentenones from 2,5-Bis(trimethylsilyl) Oxy-cyclopentadienyl Dianions and Acid Chlorides
Heng Li, Lantao Liu, Zitao Wang, Fei Zhao, Shaoguang Zhang, Wen-Xiong Zhang, and Zhenfeng Xi*
Chem. Eur. J.2011, online 20110525, DOI: 10.1002/chem.201100830
Dianionicrelay linchpins: A new type of anion relay linchpin for migrating silyl groups was developed to form the interesting gem-bis(trimethylsilyl) cyclopentenones containing a stable enol moiety. The dianion was relayed iteratively along the Cp ring with the exocyclic oxy anion as the posthouse. Furthermore, isolation and structural information of key intermediates were achieved to support the proposed mechanism.
背景介绍：
2009年，本研究室成功分离得到了双锂试剂1,4-二锂-1,3-丁二烯与一氧化碳反应产生的双锂氧代环戊二烯基双负离子活性中间体（OCp）（Lantao Liu, Wen-Xiong Zhang, Chao Wang, Congyang Wang, and Zhenfeng Xi*, Isolation, Structural Characterization and Synthetic Application of Oxy-cyclopentadienyl Dianions, Angew. Chem. Int. Ed. 2009, 48, 8111）。该类双负离子中间体代表一类全新双负离子化合物，具有丰富的反应化学和用途。
在进一步的工作中，我们坚持本研究室“基于机理研究和活性中间体的合成化学”研究理念，发现2，5位三甲基硅基取代的OCp可以作为一种新型的“阴离子接力合成子”，其在酰氯的诱导下，可以发生阴离子接力的硅基迁移反应。在反应过程中，氧负离子作为一个“驿站”将硅基从2位接力到5位。我们同时对该硅迁移机理进行了深入研究，分离并表征了反应中产生的重要中间体的单晶结构。