Active template rotaxane synthesis through the Ni-catalyzed cross-coupling of alkylzinc reagents with redox-active esters
作者:Javier Echavarren、Malcolm A. Y. Gall、Adrian Haertsch、David A. Leigh、Vanesa Marcos、Daniel J. Tetlow
DOI:10.1039/c9sc02457c
日期:——
The synthesis of unsymmetrical axle [2]rotaxanes through a recently developed Ni-catalyzed C(sp3)–C(sp3) cross-coupling of redox-active esters (formed directly from carboxylic acids) and organozinc reagents (derived from alkyl bromides) is reported. The method also furnishes, as a minor product, the symmetrical axle [2]rotaxanes resulting from the homo-coupling of the organozinc half-thread. The rotaxanes
通过最近开发的镍催化C(sp 3 )–C(sp 3 )交叉偶联氧化还原活性酯(直接由羧酸形成)和有机锌试剂(衍生自烷基溴)合成不对称轴[2]轮烷)被报道。该方法还提供了由有机锌半线均质偶联产生的对称轴[2]轮烷作为次要产物。轮烷的产率高达56%,不对称轮烷的比例随着大环空腔尺寸的增加而增加。在不存在氧化还原活性酯的情况下,即使自偶联轮烷产物不掺入氧化还原活性酯结构单元,也不会形成轮烷。Ni( III )中间体与这些观察结果一致,为之前假设的Ni催化交叉偶联反应机制提供了支持。