Copper Catalysis for Nicotinate Synthesis through β‐Alkenylation/Cyclization of Saturated Ketones with β‐Enamino Esters

The first example of a Cu‐catalyzed and 4‐OH‐TEMPO mediated intermolecular [3+3] annulation of saturated ketones with β‐enamino esters is reported herein, which was successfully used for the synthesis of versatile nicotinates through sequential β‐C(sp3)‐H bond alkenylation, enamine‐carbonyl condensation and aromatization. This protocol tolerates a variety of functional groups, thereby providing a practical and efficient method for the fabrication of 5H‐chromeno[4,3‐b]pyridin‐5‐one skeletons.