Ternary catalytic systems consisting of cobalt salts, phosphine ligands, and Grignard reagents promote addition of arylpyridines and imines to unactivated internal alkynes with high regio- and stereoselectivities. Deuterium-labeling experiments suggest that the reaction involves chelation-assisted oxidative addition of the aryl C-H bond to the cobalt center and insertion of the C-C triple bond into the Co-H bond, followed by reductive elimination of the resulting diorganocobalt species.
Synthesis of a Dimeric Base-Stabilized Cobaltosilylene Complex for Catalytic C−H Bond Functionalization and C−C Bond Formation
作者:Sabrina Khoo、Jiajia Cao、Ming-Chung Yang、Yu-Liang Shan、Ming-Der Su、Cheuk-Wai So
DOI:10.1002/chem.201803410
日期:2018.9.25
The synthesis of a dimeric base‐stabilized cobaltosilylene complex and its catalytic reactions are described. Treatment of the amidinato silicon(I) dimer [LSi:]2 (1; L=PhC(NtBu)2) with CoBr2 in toluene for 10 days afforded the dimeric amidinato cobaltosilylene [(LSi)μ‐CoBr(LSiBr)}]2 (2), which is speculated to proceed via “LSiCoBr” and “LSiBr” intermediates in the reaction. Compound 2 is paramagnetic
描述了二聚体碱稳定的钴亚甲硅烷基络合物的合成及其催化反应。用甲苯中的CoBr 2处理a胺基硅(I)二聚体[LSi:] 2(1 ; L = PhC(N t Bu)2)10天,得到meric胺基钴亚甲硅烷基二聚体[(LSi)μ- CoBr(LSiBr) )}] 2(2),推测其通过反应中的“ LSiCoBr”和“ LSiBr”中间体进行。化合物2是顺磁性的,有效磁矩为2.8μB。通过单晶X射线晶体学和DFT研究阐明了其电子结构。它能够催化CH键功能化,其中2,膦和MeMgI的组合可以区域和立体选择性地促进炔烃中C≡C三键加到芳基吡啶的邻CH位上。此外,化合物2催化了芳基氯化物与格氏试剂2-甲磺基溴化镁之间的Kumada型偶联反应。