Bis(oxazoline) Iron Complexes Enable Tuning of Lewis Acidity for Catalytic Carbonyl–Olefin Metathesis

Carbonyl–olefin metathesis reactions are powerful transformations for carbon–carbon bond formation. Despite recent progress, limitations exist that hamper the synthetic generality of the reported approaches. Catalytic systems that will enable tuning of their Lewis acidity and consequently the selective activation of specific substrate classes are expected to greatly enhance the current scope. We herein report the development of cationic iron-bis(oxazoline) complexes as powerful catalysts that enable the alteration of Lewis acidity to efficiently convert substrate types that were previously found to be incompatible with existing catalytic systems in carbonyl–olefin ring-closing metathesis.