Unravelling the hidden link of lithium halides and application in the synthesis of organocuprates

As a versatile metal, copper has demonstrated a wide application in acting as both organometallic reagent and catalyst. Organocuprates are among the most used organometallic reagents in the formation of new carbon–carbon bonds in organic synthesis. Therefore, revealing the real structures of organocuprates in solution is crucial to provide insights into the reactivity of organocuprates. Here we provide several important insights into organocuprate chemistry. The main finding contains the following aspects. The Cu(0) particles were detected via the reduction of CuX by nBuLi or PhLi. The Cu(II) precursors CuX(2) (X=Cl, Br) could be used for the preparation of Gilman reagents. In addition, we provide direct evidence for the role and effect of LiX in organocuprate synthesis. Moreover, the EXAFS spectrum provides direct evidence for the exact structure of Li(+) CuX(2)(−) ate complex in solution. This work not only sheds important light on the role of LiX in the formation of organocuprates but also reports two new routes for organocuprate synthesis.