Enantioselective C2–H Alkylation of Pyridines with 1,3-Dienes via Ni–Al Bimetallic Catalysis
作者:Jiang-Fei Li、Deng Pan、Hao-Rui Wang、Tao Zhang、Yi Li、Genping Huang、Mengchun Ye
DOI:10.1021/jacs.2c09306
日期:2022.10.19
A chiral phosphine oxide-ligated Ni–Al bimetallic catalyst was used to realize an enantioselective C2–H alkylation of pyridines without the need of a C2-block. A wide range of pyridines, including unsubstituted pyridine, C3, C4, and C2-substituted pyridines, and even complex pyridine-containing bioactive molecules are well compatible with the reaction, providing up to 81% yield and up to 97% ee.
Stereodivergent, Kinetically Controlled Isomerization of Terminal Alkenes via Nickel Catalysis
作者:Camille Z. Rubel、Anne K. Ravn、Hang Chi Ho、Shenghua Yang、Zi‐Qi Li、Keary M. Engle、Julien C. Vantourout
DOI:10.1002/anie.202320081
日期:2024.5.21
mono-transposition generates E- or Z-olefins depending on the steric properties and denticity of the ligand employed. Mechanistic studies reveal that the aryl iodide additive acts as a redox buffer for nickel in the Z-selective reaction, generating the most-selective NiII–H that outcompetes a less Z-selective NiI–H species. For the E-selective reaction, the phosphonium salt plays a dual role as an acid
镍催化的动态烯烃单转位根据所用配体的空间性质和齿数产生E-或Z-烯烃。机理研究表明,芳基碘化物添加剂在Z选择性反应中充当镍的氧化还原缓冲剂,生成选择性最高的 Ni II -H,从而击败Z选择性较低的 Ni I -H 物种。对于E-选择性反应,鏻盐起到酸和配体的双重作用,原位形成膦结合的阳离子Ni−H催化剂。