Supplementary information files for Mechanistic insight into Pd-catalyzed asymmetric alkylation of indoles with diazoesters employing bipyridine-N,N’-dioxides as chiral controllers

Supplementary files for article Mechanistic insight into Pd-catalyzed asymmetric alkylation of indoles with diazoesters employing bipyridine-N,N’-dioxides as chiral controllersMetal‐catalyzed asymmetric alkylation of indoles with α‐diazoesters is well‐known, however, the underlying mechanisms of this reaction, particularly the origin of stereoselectivity, remain uncertain. For the Pd catalysis, we address this cutting‐edge challenge from two complementary viewpoints – i) the molecular level regarding a single catalytically active Pd center; and ii) nano‐level Pd species investigating the factors favoring the appearance of the preferred catalytic centers. The formation of the active catalytic species was monitored by structural methods (NMR and ESI‐MS), and metal particles were characterized with electron microscopy (SEM, EDX). On the molecular level,chiral bipyridine‐N,N’‐dioxides proved to be competent chiral controllers. The kinetic and DFT computational data revealed a crucial role of water in the rate and selectivity determining steps and showed that the enantioselectivity of the process is controlled by the protodepalladation step. On the nano‐scale, the important effect of catalyst precursor on the overall reaction performance was shown.

补充材料：关于以双吡啶-二氧杂环戊二烯作为手性调控剂，通过钯催化靛蓝与α-偶氮酯的不对称烷基化的机制性见解金属催化的靛蓝与α-偶氮酯的不对称烷基化反应已知广泛存在，然而，该反应的内在机制，尤其是手性选择性的来源，仍不明确。对于钯催化反应，我们从两个互补的角度应对这一前沿挑战——i）从分子层面，针对单个催化活性钯中心；ii）在纳米尺度上，探究有利于优选催化中心出现的因素。通过结构方法（核磁共振和电喷雾电离质谱）监测了活性催化物种的形成，并利用电子显微镜（扫描电子显微镜、能量色散X射线光谱）对金属颗粒进行了表征。在分子层面，手性双吡啶-二氧杂环戊二烯被证明是合格的手性调控剂。动力学和DFT计算数据揭示了水在速率和选择性决定步骤中的关键作用，并表明该过程的外消旋选择性受原位去钯步骤的控制。在纳米尺度上，催化剂前体对整体反应性能的重要影响得到了展示。