Enantioselective Three‐Component Photochemical 1,4‐Bisalkylation of 1,3‐Butadiene with Pd/Cu Catalysis.

Catalysis by excited‐state palladium has emerged as an active area of research, but controlling the enantioselectivity remains a challenge. Herein, we report the use of synergistic Pd/Cu catalysis to accomplish the first three‐component photochemical 1,4‐bisalkylation reactions of 1,3‐butadiene. Consequently, α‐amino acid esters bearing quaternary stereocenters were expeditiously synthesized from three simple starting materials: an alkyl bromide, butadiene, and an aldimine ester. Experimental and computational investigation of the reaction mechanism confirmed a radical pathway involving catalysis by an excited‐state palladium species. The stereochemistry is mainly controlled by the chiral Cu catalyst. [ABSTRACT FROM AUTHOR]