Research news, May 24th, 2016
Calcium-Mediated C-H and C-F Bond Cleavage: Synthesis of Indenes and Perfluorodibenzopentalenes from 1,4-Dilithio-1,3-butadienes
Baosheng Wei, Heng Li, Wen-Xiong Zhang*, and Zhenfeng Xi*
Organometallics 2016, 35, 1458-1463.
The development of Ca-mediated reactions is of great importance and is in great demand in both organometallic and organic chemistry. In this paper, we report that calcium iodide efficiently promotes the transformation of various 1,4-dilithio-1,3- butadienes into indenes or perfluorodibenzopentalenes, via an intramolecular C−H or C−F bond cleavage, respectively. In the reaction process, the Ca-induced s-cis/trans configurational isomerization of 1,4-dilithio-1,3-butadienes is followed by the subsequent nucleophilic C−H or C−F bond activation.
Calcium-mediated organic synthesis have found a wide range of use in polymerization, alkene hydroamination, hydrosilylation and hydrogenation, etc., mainly because of the fact that calcium represents an extremely attractive element as an alternative of noble transition metals. In those successful conversions, the nucleophilicity or basicity of organocalcium compounds is crucial. In contrast to transition-metal-mediated organic synthesis, the development of Ca-mediated reactions remains limited and has been expected to become an ever-attractive area in the future.