Synthesis of Biphenanthrene Natural Products by Atroposelective Aromatic Ring‐Opening Metathesis

ABSTRACT With the unique ability to cleave and form an extensive range of carbon–carbon double and triple bonds, alkene and alkyne metathesis advanced to a preferred strategy for the synthesis of natural products. Furthermore, metathesis is ideally suited for cascade reactions and, if well‐defined chiral catalysts are employed, even for enantioselective transformations. However, while alkene and alkyne metathesis are frequently employed in the preparation of naturally occurring structures, the ring‐opening metathesis of arenes, which are prevalent in natural compounds, is not yet established as avenue for natural product total synthesis. Herein, we now describe that aromatic ring‐opening metathesis (ArROM) allows particularly short and efficient total syntheses of aromatic natural products. Moreover, by atroposelective ArROM, synthetic access to naturally occurring biphenanthrene atropisomers was possible with outstanding stereoselectivity, allowing to corroborate unusual differences in their configurational stability under ambient light.