Auxiliary-Assisted Palladium-Catalyzed Arylation and Alkylation of sp2 and sp3 Carbon−Hydrogen Bonds
摘要:
We have developed a method for auxiliary-directed, palladium-catalyzed beta-arylation and alkylation of sp(3) and sp(2) C-H bonds in carboxylic acid derivatives. The method employs a carboxylic acid 2-methylthioaniline- or 8-aminoquinoline amide substrate, aryl or alkyl iodide coupling partner, palladium acetate catalyst, and an inorganic base. By employing 2-methylthioaniline auxiliary, selective monoarylation of primary sp(3) C-H bonds can be achieved. If arylation of secondary sp(3) C-H bonds is desired, 8-aminoquinoline auxiliary may be used. For alkylation of sp(3) and sp(2) C-H bonds, 8-aminoquinoline auxiliary affords the best results. Some functional group tolerance is observed and amino- and hydroxy-acid derivatives can be functionalized. Preliminary mechanistic studies have been performed. A palladacycle intermediate has been isolated, characterized by X-ray crystallography, and its reactions have been studied.
less reactive aryl bromides as arylating reagents in the Pd(II)-catalyzed intermolecular arylation of unactivated C(sp3)–Hbonds is described. This reaction was promoted by a crucial 8-aminoquinolinyl directing group and a K2CO3 base, enabling regiospecific installation of an aryl scaffold at the β-position of carboxamides. A mechanistic study by DFT calculations reveals a C(sp3)–H activation-led
描述了在Pd(II)催化的未活化C(sp 3)-H键的分子间芳基化中使用容易获得的,反应性较低的芳基溴化物作为芳基化试剂的示例。至关重要的8-氨基喹啉基导向基团和K 2 CO 3碱促进了该反应,从而使芳基骨架可以在羧酰胺的β-位上进行区域特异性安装。通过DFT计算进行的机理研究揭示了C(sp 3)–H活化为主导的途径,该途径的特征是氧化加成为最高能量跃迁状态。
Nickel‐Catalyzed Insertion of Alkynes and Electron‐Deficient Olefins into Unactivated sp
<sup>3</sup>
CH Bonds
Insertion of unsaturated systems such as alkynes and olefins into unactivated sp3 CH bonds remains an unexplored problem. We herein address this issue by successfully incorporating a wide variety of functionalized alkynes and electron‐deficient olefins into the unactivated sp3 CH bond of pivalic acid derivatives with excellent syn‐ and linear‐ selectivity. A strongly chelating 8‐aminoquinoline directing