Research news, Sept. 14th, 2015
Reaction of Dilithio Reagents with PhSiH3: Formation of Siloles and 3-Silacyclopentenes
Baosheng Wei, Heng Li, Jianhao Yin, Wen-Xiong Zhang, and Zhenfeng Xi*
J. Org. Chem. 2015, 80, 8758-8762
Nucleophilic substitution reaction of silanes is an ideal approach for the synthetic application of silanes leading to the synthesis of organosilicon compounds. However, this method is not practical due to the inefficient substitution of the hydride ion.
The reaction chemistry between dilithio reagents and PhSiH3 has been investigated. Direct substitution of two hydride ions from PhSiH3 with the dilithio reagents led to multi-substituted siloles (silacyclopentadienes) in diethyl ether solution, with the concomitant generation of LiH. When THF was used as the solvent, the reaction between PhSiH3 and 1,4-bis(silyl) dilithio reagents afforded cis-3-silacyclopentenes stereoselectively. Siloles and silacyclopentenes have wide applications in materials science. Experimental results demonstrated that reactive LiH was generated in situ in the reaction system. Formal syn addition of LiH to silacyclopentadiene intermediates would afford silacyclopentenes, most likely via pentavalent organosilicates.