Photocatalytic Regio- and Stereoselective 3,4-Hydroxyacylmethylation of 1,3-Dienes with α-HaloAcylarenes and Water

A photocatalytic regio- and stereoselective 3,4-hydroxyacylmethylation of 1,3-dienes with α-halo acylarenes and water is developed, providing direct access to diverse (E)-allylic alcohols in moderate to excellent yields. This protocol features excellent regio- and stereocontrol (up to >20/1 rr and >20/1 E/Z), broad substrate scope, and gram-scale applicability. Mechanistic studies reveal a radical addition/SET oxidation/nucleophilic trapping cascade. The synthetic utility is further demonstrated by diverse product derivatizations.