This Article demonstrates a mild oxidatively induced C(sp3)-H activation at a high-valent Ni center. In contrast with most C(sp3)-H activation reactions at NiII, the transformation proceeds at room temperature and generates an isolable NiIV σ-alkyl complex. Density functional theory studies show two plausible mechanisms for this C-H activation process involving triflate-assisted C-H cleavage at either a NiIV or a NiIII intermediate. The former pathway is modestly favored over the latter (by â3 kcal/mol). The NiIV σ-alkyl product of C-H cleavage reacts with a variety of nucleophiles to form C(sp3)-X bonds (X = halide, oxygen, nitrogen, sulfur, or carbon). These stoichiometric transformations can be coupled using N-fluoro-2,4,6-trimethylpyridinium triflate as a terminal oxidant in conjunction with chloride as a nucleophile to achieve a proof-of-principle NiII/IV-catalyzed C(sp3)-H functionalization reaction.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation Grant CHE-1111563 as well as CHE-0840456 for X-ray instrumentation. E.C. thanks NSERC for a postdoctoral fellowship. We gratefully acknowledge Emily Norwine for the characterization of product 3-OAc . We also acknowledge the Australian National Computing Infrastructure.
© 2019 American Chemical Society.
PubMed: MeSH publication types
- Journal Article