Copper‐Catalyzed Ring‐Opening (3+2) Annulation of Cyclopropenones with Ketoxime Acetates: Access to 1,2‐Dihydro‐pyrrol‐3‐ones Bearing a Quaternary Carbon Center

Abstract A Cu(I)‐catalyzed ring‐opening (3+2) annulation of cyclopropenones with ketoxime acetates has been developed. In disclosed protocol, ketoxime acetates are selected as C−N splicing unit to participate in the transformation process, furnishing a sequence of highly functional 1,2‐dihydro‐pyrrol‐3‐one derivatives in good isolated yields. Besides, scale‐up reaction is conducted to demonstrate the practicability of developed methodology and a tentative mechanism for (3+2) annulation is also proposed.