Regioselective Tandem C–H Alkylation/Coupling Reaction of ortho -Iodophenylethylenes via C , C -Pallada(II)cycles

作者：Bin‐Bin Zhu, Wen-Bo Ye, Zhi‐Tao He, Shu‐Sheng Zhang, Chen‐Guo Feng, Guo‐Qiang Lin · 发表于：ACS Catalysis · 年份：2021 · DOI：10.1021/acscatal.1c03386 · 被引用次数：23 · 研究领域：Catalytic C–H Functionalization Methods、Catalytic Cross-Coupling Reactions、Oxidative Organic Chemistry Reactions

Five-membered C, C -pallada(II)cycles are a unique class of diorganopalladium species with favorable stability and an electron-rich nature, leading to efficient sequential reactions with diverse electrophiles and nucleophiles. Specifically, the development of aryl-alkenyl-palladacycle-based transformations could provide an attractive approach with regio- and stereocontrol for the construction of multifunctionalized arylethylenes. However, currently, the C, C -pallada(II)cycle formation relies on a rigid skeleton or steric congestion in the backbone to promote cyclopalladation, and the formation of aryl-alkenyl-palladacycle without an α-substituent has not been achieved. Furthermore, reactions that could discriminate between the two sp 2 carbon centers of such C (sp 2 ), C (sp 2 )-palladacycle remain elusive. Herein, we report a regioselective three-component tandem alkylation/coupling reaction applicable for a variety of non-, α-, or β-substituted and α,β-disubstituted ortho -iodophenylethylenes. Electron-rich 2-pyridone ligands are employed to enable the cyclopalladation process leading to aryl-alkenyl-palladacycle intermediates, of which the two C–Pd bonds are discriminated toward alkylation by their inherent steric and electronic differences. Good linear free-energy relationships between regio-/chemoselectivities and Hammett σ values are observed.