A Practical Transition Metal-Free Aryl-Aryl Coupling Method: Arynes as Key Intermediates
作者:Frédéric R. Leroux、Laurence Bonnafoux、Christophe Heiss、Françoise Colobert、Don Antoine Lanfranchi
DOI:10.1002/adsc.200700211
日期:2007.12.10
and, stabilization of the resulting 2-biaryllithium intermediate by in situ transfer of bromine or iodine from the starting material. This straightforward transition metal-free access to biaryls allows the preparation of highly valuable halobiaryls on a gram scale in excellent yields. These precursors can be subsequently functionalized by highly regioselective halogen/metal permutations into a vast
用1,2-二溴苯或1-溴-2-碘苯处理各种芳基锂中间体后,不对称的邻,邻,二,三,甚至四取代的溴或碘代二芳基变得很容易获得。在所有这些反应中的关键步骤是将有机锂前体亲核加成到通过β-消除卤化锂而从中释放出的瞬态芳烃物种中,并通过原位稳定所得的2-联芳基锂中间体从原料中转移溴或碘。这种无过渡金属的直接进入联芳基的方法使得可以以极高的收率以克为单位制备高度有价值的卤代芳基。这些前体可随后通过高度区域选择性的卤素/金属置换功能化为各种各样的目标分子。这在几种单和二膦配体的合成中得到了证明。