Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, Shanghai University, Shanghai 200444, China.
Chem Soc Rev. 2021 Mar 21;50(6):4162-4184. doi: 10.1039/d0cs01107j. Epub 2021 Feb 3.
Transformation of sterically hindered tertiary alkyl electrophiles under nickel-catalyzed conditions to forge C(sp)-C bonds and simultaneously create challenging all-carbon quaternary centers has received growing attention in the recent years. The unique nature of nickel featuring flexible oxidation states ranging from Ni to Ni, allows the effective activation of tertiary alkyl electrophiles through ionic (2e) or radical pathways. In nickel-catalyzed coupling of tertiary alkyl electrophiles, the competitive β-H elimination upon the resulting alkyl-Ni intermediate is relatively slow, thus benefiting the C-C bond forming process. Meanwhile, nickel-catalyzed radical addition of tertiary alkyl electrophiles to unsaturated C-C bonds has also advanced rapidly due to the successful incorporation of carboxylic acid and alcohol derivatives as radical precursors, and more importantly due to further interception of the intermediate radical adducts with nucleophiles and electrophiles to accomplish three-component cascade reactions. This review highlights these state-of-the-art nickel-catalyzed transformations of tertiary electrophiles, organized by reaction types with emphasis on the reaction mechanisms.
近年来，在镍催化条件下，空间位阻较大的叔烷基亲电试剂的转化，用于构建 C(sp)-C 键并同时生成具有挑战性的全碳季碳中心，引起了越来越多的关注。镍独特的性质，其氧化态可灵活变化，从 Ni 到 Ni，可通过离子（2e）或自由基途径有效活化叔烷基亲电试剂。在镍催化的叔烷基亲电试剂偶联反应中，生成的烷基-Ni 中间体的β-H 消除反应相对较慢，因此有利于 C-C 键形成过程。同时，由于成功地将羧酸和醇衍生物作为自由基前体纳入其中，以及更重要的是，由于中间体自由基加成物与亲核试剂和亲电试剂的进一步拦截，以完成三组分级联反应，镍催化的叔烷基亲电试剂对不饱和 C-C 键的自由基加成也迅速发展。本文综述了这些最先进的镍催化的叔亲电试剂转化反应，根据反应类型进行了组织，并重点介绍了反应机理。
