ABSTRACT
The rational synthesis of nanographenes and carbon nanoribbons directly on nonmetallic surfaces has been an elusive goal for a long time. We report that activation of the carbon (C)-fluorine (F) bond is a reliable and versatile tool enabling intramolecular aryl-aryl coupling directly on metal oxide surfaces. A challenging multistep transformation enabled by C-F bond activation led to a dominolike coupling that yielded tailored nanographenes directly on the rutile titania surface. Because of efficient regioselective zipping, we obtained the target nanographenes from flexible precursors. Fluorine positions in the precursor structure unambiguously dictated the running of the "zipping program," resulting in the rolling up of oligophenylene chains. The high efficiency of the hydrogen fluoride zipping makes our approach attractive for the rational synthesis of nanographenes and nanoribbons directly on insulating and semiconducting surfaces.
ABSTRACT
Thermally activated γ-aluminium oxide was found to be very effective for C-F bond activation in trifluoromethylated arenes. Depending on the activation degree the respective arenes can be converted either to cyclic ketones or to the respective carboxylic acids with good to excellent yields.
ABSTRACT
A strategy for effective intramolecular aryl-aryl coupling of fluoroarenes through Al(2)O(3)-mediated HF elimination is reported. It is demonstrated that the C-F bond, which is widely believed to be the most passive functionality in organic chemistry, can be reconsidered as a useful functional group allowing very effective C-C bond formation. The solid-state strategy presented in this study opens the possibility for facile syntheses of insoluble extended polycyclic aromatic hydrocarbons.
