Regioselective C–H Bond Cleavage/Alkyne Insertion under Ruthenium Catalysis
摘要:
The ruthenium-catalyzed coupling reactions of benzamides with alkynes in the presence of acetic acid as a promoter smoothly proceeded regio- and stereoselectively through a directed C-H bond cleavage to produce the corresponding ortho-alkenylated products. Phenylpyrazoles and related substrates also underwent a similar coupling to give dialkenylated products selectively. Several competitive experiments were performed to obtain mechanistic insight into both the mono- and dialkenylation reactions.
Recyclable Ruthenium Catalyst for Distal
<i>meta</i>
‐C−H Activation
作者:Isaac Choi、Valentin Müller、Yanhui Wang、Kai Xue、Rositha Kuniyil、Loren B. Andreas、Volker Karius、Johan G. Alauzun、Lutz Ackermann
DOI:10.1002/chem.202003622
日期:2020.11.26
unprecedented hybrid‐ruthenium catalysis for distal meta‐C−H activation. The hybrid‐ruthenium catalyst was recyclable, as was proven by various heterogeneity tests, and fully characterized with various microscopic and spectroscopic techniques, highlighting the physical and chemical stability. Thereby, the hybrid‐ruthenium catalysis proved broadly applicable for meta‐C−Halkylations of among others purine‐based
Isolation of Cp*Co<sup>III</sup>
-Alkenyl Intermediate in Efficient Cobalt-Catalyzed C−H Alkenylation with Alkynes
作者:Malay Sen、Nimmakuri Rajesh、Balakumar Emayavaramban、J. Richard Premkumar、Basker Sundararaju
DOI:10.1002/chem.201705183
日期:2018.1.9
A general and efficient procedure for C−H alkenylation of arenes with a broad substrate scope catalyzed by Cp*CoIII was demonstrated with alkynes. A highly selective mono‐alkenylation and sequential bis‐C−H bond functionalization was displayed to exemplify the versatility of the cobalt catalyst. Isolation of cationic Cp*CoIII–alkenyl intermediate was achieved under identical catalytic conditions to
用炔烃证明了由Cp * Co III催化的具有广泛底物范围的芳烃的CH链烯基化的通用有效方法。高选择性的单烯基化和顺序的双CH键功能化显示了钴催化剂的多功能性。在相同的催化条件下实现了阳离子Cp * Co III-烯基中间体的分离,以进一步建立拟议的途径。
Cobalt(III)-Catalyzed Hydroarylation of Allenes via C–H Activation
The hydroarylation of allenes via C–H activation was achieved with a versatile cationic cobalt(III) catalyst. Step- and atom-economical access to alkenylated heteroarenes is thus provided in a highly chemo- and regioselective manner. Detailed mechanistic studies were conducted, including kinetic studies and Hammett analysis, suggesting the catalytic cycle being initiated with a reversible N-ligand
Cobalt(III)-Catalyzed Aryl and Alkenyl CH Aminocarbonylation with Isocyanates and Acyl Azides
作者:Jie Li、Lutz Ackermann
DOI:10.1002/anie.201501926
日期:2015.7.13
cobalt(III) catalyst that shows high functional group tolerance. The CH functionalization occurred with excellent chemo‐, site‐, and diastereoselectivity and enabled step‐economical reactions with isocyanates or acyl azides.