NHC‐Catalyzed Oxidative Annulation of α,β‐unsaturated Aldehydes with Benzyl Ketones: Direct Access to 4,5,6‐Trisubstituted Dihydropyranones

A novel and efficient access to polysubstituted dihydropyranones was developed by N‐heterocyclic carbene catalyzed annulation reaction of α,β‐unsaturated aldehydes and benzyl ketones under oxidative conditions. Various α,β‐unsaturated aldehydes with long‐chain aliphatic and aromatic substitution groups were compatible in this transformation, giving the corresponding products in good to excellent yields under mild conditions. This strategy features simple and readily available materials and mild reaction conditions and provides a green and practical method for the rapid synthesis of functionalized dihydropyranones.