The Preparation and Resolution of Novel Axially Chiral Pyrazine‐Containing P,N Ligands for Asymmetric Catalysis and Their Application in Palladium‐Catalysed Allylic Substitution
作者:Sarah Kelly、Richard Goddard、Patrick J. Guiry
DOI:10.1002/hlca.202100205
日期:2022.1
design and synthesis of two novel pyrazine-containing ligands, 3,6-diisopropyl-Pyrazinap and Np−Cy-Pyrazinap, has been described. Their synthesis was accomplished in six and nine steps, respectively, in which the key steps were the formation of the biaryl linkage through a Suzuki cross-coupling reaction and the formation of the aryl to phosphorus bond employing nickel catalysis. Both ligands were resolved
已经描述了两种新型含吡嗪配体 3,6-二异丙基-Pyrazinap 和 Np-Cy-Pyrazinap 的设计和合成。它们的合成分别分六步和九步完成,其中关键步骤是通过Suzuki交叉偶联反应形成联芳基键,以及使用镍催化形成芳基与磷键。两种配体都通过非对映体钯环的形成来分离,在由 3,6-二异丙基-吡嗪酸形成的分离的非对映体的情况下,X 射线晶体结构显示出具有轴向手性 ( S)-配置。这两种对映纯配体被应用于钯催化的 1,3-二苯基丙-2-烯基乙酸酯与丙二酸二甲酯的烯丙基烷基化反应,转化率高达 100% 和 99%,对映选择性高达 92% ee 和 78% ee , 分别。制备了一系列1,1,3-三苯基烯丙基和1,3-二苯基烯丙基钯配合物,并通过2D-COSY和NOESY NMR光谱实验阐明了它们的溶液结构和动力学行为。