Aromatic ring-opening metathesis

Aromatic compounds are used across chemistry and materials science as a result of their stability, characteristic interactions, defined molecular shape and the numerous approaches for their synthesis by a diversity of cyclization reactions¹. By contrast, the cleavage of inert aromatic carbon-carbon bonds remained largely unfeasible owing to the unfavourable energetics of disrupting aromaticity on ring opening. For non-aromatic structures, alkene metathesis catalysed by transition-metal alkylidenes is established as one of the most versatile carbon-carbon bond-forming and -breaking reactions^2,3. However, despite remarkable advancements, strategies to open aromatic compounds by metathesis remain elusive⁴. Here we report aromatic ring-opening metathesis (ArROM) for the cleavage of aromatic rings, including tetraphene, naphthalene, indole, benzofuran and phenanthrenes, by using Schrock-Hoveyda molybdenum catalysts. The reactions for each ring system proceed through unique alkylidene intermediates. We further show the possibility for stereoselective ArROM with exquisite catalyst control over the configuration of atropisomers. ArROM is, therefore, a viable and efficient approach to catalytically transform and interconvert various aromatics without the requirement for any reagents or photoexcitation.