Copper-Catalyzed Direct C-H Alkylation of Polyfluoroarenes by Using Hydrocarbons as an Alkylating Source
| Autor: | Weilong Xie, Dong-Wook Kim, Joon Heo, Sukbok Chang |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Alkane
chemistry.chemical_classification Hydrogen bond Aryl General Chemistry Alkylation 010402 general chemistry 01 natural sciences Biochemistry Combinatorial chemistry Catalysis Coupling reaction 0104 chemical sciences chemistry.chemical_compound Colloid and Surface Chemistry chemistry Molecule Reactivity (chemistry) |
| Zdroj: | Journal of the American Chemical Society. 142(16) |
| ISSN: | 1520-5126 |
| Popis: | Construction of carbon-carbon bonds is one of the most important tools in chemical synthesis. In the previously established cross-coupling reactions, prefunctionalized starting materials were usually employed in the form of aryl or alkyl (pseudo)halides or their metalated derivatives. However, the direct use of arenes and alkanes via a 2-fold oxidative C-H bond activation strategy to access chemoselective C(sp2)-C(sp3) cross-couplings is highly challenging due to the low reactivity of carbon-hydrogen (C-H) bonds and the difficulty in suppressing side reactions such as homocouplings. Herein, we present the new development of a copper-catalyzed cross-dehydrogenative coupling of polyfluoroarenes with alkanes under mild conditions. Relatively weak sp3 C-H bonds at the benzylic or allylic positions, and nonactivated hydrocarbons could be alkylated by the newly developed catalyst system. A moderate-to-high site selectivity was observed among various C-H bonds present in hydrocarbon reactants, including gaseous feedstocks and complex molecules. Mechanistic information was obtained by performing combined experimental and computational studies to reveal that the copper catalyst plays a dual role in activating both alkane sp3 C-H bonds and sp2 polyfluoroarene C-H bonds. It was also suggested that the noncovalent π-π interaction and weak hydrogen bonds formed in situ between the optimal ligand and arene substrates are key to facilitating the current coupling reactions. |
| Databáze: | OpenAIRE |
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