Cerium-Catalyzed Formal Cycloaddition of Cycloalkanols with Alkenes through Dual Photoexcitation

We describe a synergistic
utilization of cerium photocatalysis
and photoinduced electron transfer catalysis that enables an atom-
and step-economical ring expansion of readily available cycloalkanols.
This operationally simple protocol provides rapid access to privileged
and synthetically challenging bridged lactones. The mild catalytic
manifold has been adapted to continuous flow for scale-up applications
and employed for the concise synthesis of polycyclic core of nepalactones.