摘要/Abstract

设计并合成了两类新型的PNP钳状配体, 一类以吡啶结构为骨架, 另一类以1,3,5-三嗪结构为骨架. 将这两类配体应用于钴催化的硅氢还原末端炔烃N-(3-炔丁基)对甲苯磺酰胺(8a)的反应中, 发现两者对反应速率和选择性均有重大影响. 其中具有吸电子取代基的吡啶结构的配体2,6-双((S)-2-((二苯基膦)甲基)吡咯烷基)烟酸乙酯(L5b)可以高效促进8a的迁移半氢化反应, 主要给出反式内烯产物. 通过进一步筛选金属催化剂、溶剂和还原剂, 确定了获得反式内烯产物的最优反应条件为CoCl₂/L5b/SiH(OMe)₃/四氢呋喃(THF). 运用最优条件, 研究了另外8种末端炔烃8b~8i的迁移半氢化反应, 反应产物仍主要以反式内烯为主. 简而言之, 通过配体L5b发展了一种末端炔烃迁移还原的方法.
关键词: PNP钳状配体, 吡啶, 1,3,5-三嗪, 钴催化, 末端炔烃, 迁移半氢化反应, 反式内烯
Two types of novel PNP pincer ligands were designed and synthesized. One had a pyridine core and the other had a 1,3,5-triazine. Evaluation of these ligands in cobalt catalyzed semihydrogenation by silane of terminal alkyne N-(but-3- yn-1-yl)-4-methylbenzenesulfonamide (8a) was carried out, in which both had significant effects on the reaction rate and selectivity. Ethyl 2,6-bis((S)-2-((diphenylphosphanyl)methyl)pyrrolidin-1-yl)nicotinate (L5b), which had pyridine skeleton with electron-withdrawing substituent, promoted the migratory semihydrogenation of 8a giving E-2-alkene predominatly. Further screening of metal catalysts, solvents and reducing agents revealed that the optimal reaction condition was CoCl₂/L5b/ SiH(OMe)₃/trifluoroacetic acid (THF) for E-2-alkene product. More terminal alkynes 8b~8i were tested under the optimal reaction condition to afford E-2-alkene mainly. In brief, using ligand L5b, a method of migratory semihydrogenation of terminal alkynes was developed.
Key words: PNP pincer ligand, pyridine, 1,3,5-triazine, cobalt catalysis, terminal alkyne, migratory semihydrogenation, E-2-alkene


PDF全文下载地址:

点我下载PDF