Copper‐Catalyzed α‐Carbamoylation of Cyclic β‐Ketoesters

A copper‐catalyzed, base‐free α‐carbamoylation of cyclic β‐ketoesters with isocyanates has been developed. While conventional base‐promoted methods suffer from a spontaneous intramolecular rearrangement that leads to undesired imides, this protocol utilizes a Cu(OTf) ₂ /bisoxazoline (BOX) catalytic system to effectively suppress the rearrangement pathway. The reaction provides efficient access to various α‐substituted β,β′‐dicarbonyl amides bearing an all‐carbon quaternary center in high yields with a broad substrate scope and excellent functional group tolerance.