AI Article Synopsis
- The fluoro group traditionally has a minor influence on electrophilic aromatic substitutions, but a structurally unique C-F bond can significantly stabilize positively charged intermediates during these reactions.
- A specific molecule was synthesized that showcases a strong C-F⋅⋅⋅Ar interaction, which plays a crucial role in the molecule's chemistry and its spectroscopic properties.
- The study found that this C-F⋅⋅⋅Ar interaction can enhance the rate of aromatic nitration reactions by over 1500 times, demonstrating that fluorine can act as an activating group rather than just a deactivating one.
Article Abstract
It is known that the fluoro group has only a small effect on the rates of electrophilic aromatic substitutions. Imagine instead a carbon-fluorine (C-F) bond positioned tightly over the π cloud of an aryl ring-such an orthogonal, noncovalent arrangement could instead stabilize a positively charged arene intermediate or transition state, giving rise to novel electrophilic aromatic substitution chemistry. Herein, we report the synthesis and study of molecule 1, containing a rigid C-F⋅⋅⋅Ar interaction that plays a prominent role in both its reaction chemistry and spectroscopy. For example, we established that the C-F⋅⋅⋅Ar interaction can bring about a >1500 fold increase in the relative rate of an aromatic nitration reaction, affording functionalization on the activated ring exclusively. Overall, these results establish fluoro as a through-space directing/activating group that complements the traditional role of fluorine as a slightly deactivating aryl substituent in nitrations.
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| http://dx.doi.org/10.1002/anie.201601989 | DOI Listing |
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