Dual Co/Photoredox‐Catalyzed Regio‐ and Stereoselective Synthesis of Highly Functional 1,3‐Dienes

Abstract A dual Co/photoredox catalytic coupling of 1,3‐enynes and α,ß‐unsaturated aliphatic aldehydes and ketones has been developed that creates access to highly functional 1,3‐diene synthons through a regio‐ and stereoselective carbon‐carbon coupling process. The scope of the process features diverse functionalized scaffolds with a high degree of molecular complexity. The synthetic utility of these 1,3‐dienes is demonstrated including a telescoped, one‐pot approach using an alkynyl cyclic carbonate as a 1,3‐enyne surrogate offering direct access to the 1,3‐diene product. Mechanistic analysis involving control reactions, deuterium labeling studies and DFT calculations are in line with the in situ formation of a Co─H species and an outer‐sphere coupling pathway in which a regio‐ and stereoselective coupling occurs between a dienyl radical and carbonyl species.