Practical Direct α-Arylation of Cyclopentanones by Palladium/Enamine Cooperative Catalysis.

Direct arylation of cyclopentanones has been a long-standing challenge because of competitive self-aldol condensation and multiple arylations. Reported herein is a direct mono-α-C-H arylation of cyclopentanones with aryl bromides which is enabled by palladium/amine cooperative catalysis. This method is scalable and chemoselective with broad functional-group tolerance. Application to controlled sequential arylation of cyclopentanones has been also demonstrated.