鎳金屬催化吡啶對位烷基化之反應性研究

Abstract

在本論文中，我們利用鎳金屬碳烯催化系統，活化吡啶 (pyridine) 與其衍生物的對位碳氫鍵，並引入各種烯烴同時進行雙鍵異構化反應 (isomerization) 及碳-氫鍵催化加成反應的連鎖反應 (tandem reaction)。我們藉由不同的配位基 (ligand) 以及路易士酸，控制產物的位向選擇性。使用配位基 (amino NHC) 和路易士酸 (AlMe3) 可以得到吡啶對位位置碳氫鍵活化的分支結構產物；使用立體結構較大的配位基 (IPr) 以及路易士酸 (MAD)，則可以得到直鏈結構的產物。我們推測會得到分支結構的產物是因為苯丙烯雙鍵異構化反應速率大於碳氫鍵活化速率，我們也透過GC實驗以及動力學同位素標記實驗 (KIE) 去推論出整個反應機制。

In this thesis, nickel mediated tandem alkene isomerization and para-C-H functionalizaton of pyridines with allylbenzene was developed. We can control the positional selectivity of hydroheteroarylated products by using different ligands and Lewis acids. The branched product with the CH functionalization occurred at para-position of pyridine were obtained as the amino NHC ligand and Lewis acid AlMe3 was used in this reaction. We speculated that the selectivity for the branch adduct is due to a fast olefinic isomerization of allylbenzene followed by the slow C-H bond activation of pyridine. In the presence of a bulky IPr NHC ligand and Lewis acid, the selectivity for linear product was obtained. The mechanism of this selective CH activation is also proposed and examined by GC analysis and kinetic isotope experiments.