Formation of Polycyclic Lactones through a Ruthenium-Catalyzed Ring-Closing Metathesis/Hetero-Pauson–Khand Reaction Sequence

Processes that form multiple carbon–carbon bonds in one operation can generate molecular complexity quickly and therefore be used to shorten syntheses of desirable molecules. We selected the hetero-Pauson–Khand (HPK) cycloaddition and ring-closing metathesis (RCM) as two unique carbon–carbon bond-forming reactions that could be united in a tandem ruthenium-catalyzed process. In doing so, complex polycyclic products can be obtained in one reaction vessel from acyclic precursors using a single ruthenium additive that can catalyze sequentially two mechanistically distinct transformations.