配体控制钯催化C-H键活化构建氮杂环的理论研究

Based on transition metal-catalyzed C-H activation, it has become an effective strategy for the synthesis of cyclic compounds due to its atom economy and efficiency. However, most organic molecules contain multiple C-H bonds, so selectively activating the desired C-H bond for target compound synthesis has been a major focus of chemists in recent years. In order to explore the intrinsic factors and related reaction mechanisms of ligand-controlled transition metal palladium-catalyzed C-H selective activation, this study selected the reaction of ligand-controlled palladium-catalyzed C-H activation of ortho-bromoaniline to construct nitrogen-containing rings reported by the Olivier Baudoin group as a template reaction. Theoretical calculations were used to investigate the reaction mechanisms and the source of chemical selectivity under different ligand conditions. The theoretical calculation results were consistent with experimental reports, indicating that concerted metal deprotonation is the determining step for the reaction selectivity. When the ligand is triphenylphosphine, the activation of C(sp2)-H bonds is favorable, leading to the formation of C(sp2)-C(sp2) coupling products. When the ligand is carbene (BIAN-IMes), the activation of C(sp3)-H bonds is favorable, resulting in the formation of C(sp3)-C(sp2) coupling products. The reason for the chemical selectivity was explained by analyzing the computational results and the electrophilicity index of the key intermediate center palladium.