Superelectrophilic Aluminum(III)-Ion Pairs Promote a Distinct Reaction Path for Carbonyl-Olefin Metathesis of Medium-Sized Rings

We describe the development of a new catalyst system for carbonyl-olefin ring-closing metathesis reactions that relies on Lewis acidic superelectrophiles and significantly expands the current scope of this transformation to medium-sized rings. Importantly, these superelectrophiles are shown to promote carbonyl-olefin metathesis via a distinct and unprecedented mechanism.