Asymmetric Synthesis of Tri- and Tetrasubstituted Trifluoro­methyl Dihydro­pyranones from α‑Aroyloxy­aldehydes via NHC Redox Catalysis

The asymmetric synthesis of tri- and tetra­substituted trifluoro­methyl di­hydro­pyranones via an NHC-catalyzed redox process, introducing methyl, benzyl, and aryl substituents to the C(5) position, is presented. Their substrate-controlled derivatization into δ-lactones and cyclic hemi­acetals containing stereo­genic trifluoro­methyl groups is also described.