Highly Selective Pd-Catalyzed Direct C–F Bond Arylation of Polyfluoroarenes
作者:Zhi-Ji Luo、Hai-Yang Zhao、Xingang Zhang
DOI:10.1021/acs.orglett.8b00692
日期:2018.5.4
A directing-group-free palladium-catalyzeddirectarylation of simple polyfluoroarenes with arylboronic acids through selective C–F bond activation is described. The combination of Pd(OAc)2 with BrettPhos was identified as an efficient catalytic system to promote the reaction with high regioselectivity and broad substrate scope. Preliminary mechanistic studies reveal that the oxidative addition of
The use of a complex of the form Z—M—OR in the carboxylation of a substrate is described. The group Z is a two-electron donor ligand, M is a metal and OR is selected from the group consisting of OH, alkoxy and aryloxy. The substrate may be carboxylated at a C—H or N—H bond. The metal M may be copper, silver or gold. The two-electron donor ligand may be a phosphine, a carbene or a phosphite ligand. Also described are methods of manufacture of the complexes and methods for preparing isotopically labelled caboxylic acids and carboxylic acid derivatives.
AbstractFluorinated organoboranes serve as versatile synthetic precursors for the preparation of value‐added fluorinated organic compounds. Recent progress has been mainly focused on the transition‐metal catalyzed defluoroborylation. Herein, we report a photocatalytic defluoroborylation platform through direct B−H activation of N‐heterocyclic carbene boranes, through the synergistic merger of a photoredox catalyst and a hydrogen atom transfer catalyst. This atom‐economic and operationally simple protocol has enabled defluoroborylation of an extremely broad scope of multifluorinated substrates including polyfluoroarenes, gem‐difluoroalkenes, and trifluoromethylalkenes in a highly selective fashion. Intriguingly, the defluoroborylation protocol can be transition‐metal free, and the regioselectivity obtained is complementary to the reported transition‐metal‐catalysis in many cases.