Research news, Apr. 8th, 2014
Magnesiacyclopentadienes as the First Alkaline-Earth Metallocyclopentadienes: Facile Synthesis, Structural Characterization, and Synthetic Application
Junnian Wei, Liang Liu, Ming Zhan, Ling Xu, Wen-Xiong Zhang, and Zhenfeng Xi*
Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201310116
Metallocyclopentadienes have attracted much attention as building blocks for synthetic chemistry as well as key intermediates in many metal-mediated or catalyzed reactions. However, metallocyclopentadienes of the alkaline-earth metals have not been reported, to say nothing of their structures, reaction chemistry and synthetic applications. In this work, the first series of magnesiacyclopentadienes, spiro dilithio magnesiacyclopentadienes and dimagnesiabutadiene were highly efficiently synthesized from 1,4-dilithio 1,3-butadienes. Single-crystal X-ray structural analysis of these magnesiacycles revealed unique structural characteristics and bonding modes. Their reaction chemistry and synthetic application were preliminarily studied. An efficient synthetic method for amino cyclopentadienes was established through their reaction with thioformamides. Experimental and DFT calculation demonstrated that these magnesiacyclopentadienes could be regarded as di-Grignard reagents and the two Mg-C(sp2) bonds showed synergetic effect when reacting with substrates.