Regio- and Enantioselective C–H Cyclization of Pyridines with Alkenes Enabled by a Nickel/N-Heterocyclic Carbene Catalysis
作者:Wu-Bin Zhang、Xin-Tuo Yang、Jun-Bao Ma、Zhi-Ming Su、Shi-Liang Shi
DOI:10.1021/jacs.9b00931
日期:2019.4.10
pyridines are ubiquitous scaffolds in many bioactive molecules. A highly regio- and enantioselective Ni(0)-catalyzed endo-selective C-H cyclization of pyridines with alkenes has been developed. An unprecedented enantioselective C-H activation at pyridyl 3- or 4-positions was enabled by bulky chiral N-heterocyclic carbene ligands. This protocol provides expedient access to a series of optically active
环状吡啶是许多生物活性分子中普遍存在的支架。已开发出高度区域选择性和对映选择性 Ni(0) 催化的吡啶与烯烃的内选择性 CH 环化。庞大的手性 N-杂环卡宾配体实现了吡啶基 3 位或 4 位前所未有的对映选择性 CH 活化。该协议提供了对一系列光学活性 5,6,7,8-四氢喹啉和 5,6,7,8-四氢异喹啉的便利访问,这些化合物否则难以获得,中高产率(产率高达 99%)和对映选择性(高达 99% ee)。据我们所知,这是吡啶对映选择性 CH 环化成手性环化产物的第一个例子。