The direct Pd-catalyzed γ-arylation of amino acid esters bearing a removable N-(2-pyridyl)sulfonyl directing group is described. A variety of N-(2-pyridyl)sulfonamide amino acid derivatives, including α-quaternary amino acid and β-amino acid substrates, react with iodoarenes in the presence of Pd(OAc)2 to provide γ-arylated products in synthetically useful yields. An unprecedented remote C(sp3)âH arylation of dipeptides is presented, illustrating the compatibility of the method with the presence of the peptidic bond. The process occurs without racemization at the Cα center and the auxiliary controlling group can be easily installed and removed in the amino acid backbone. A bimetallic PdII γ-metalated complex has been isolated and characterized showing the key role exerted by the (2-pyridyl)sulfonyl unit.
描述了一种直接的Pd催化γ-芳基化反应,适用于带有可去除的N-(2-
吡啶基)磺酰指向基团的
氨基酸酯。多种N-(2-
吡啶基)磺
酰胺氨基酸衍
生物,包括α-四取代
氨基酸和β-
氨基酸底物,在Pd(
OAc)2的存在下与
碘芳烃反应,生成合成有用产率的γ-芳基化产品。提出了一种前所未有的远程C(sp3)–H芳基化反应,用于二肽,展示了该方法与肽键存在的兼容性。该过程在Cα中心不发生外消旋化,并且辅助控制基团可以很方便地在
氨基酸骨架中安装和去除。分离并表征出一种双
金属PdII γ-
金属化复合物,显示了(2-
吡啶基)磺酰单元所发挥的关键作用。