Organocatalytic Asymmetric Cyclization Reactions with γ‐Hydroxyenones

This review article provides an overview of the recent developments in organocatalytic asymmetric cyclization strategies utilizing γ‐hydroxyenones. Due to the bifunctional nature of γ‐hydroxyenones, it is a powerful building block for synthesizing oxygen‐ and nitrogen‐containing heterocycles. The cyclization strategies are systematically categorized based on the nature of the organocatalysts employed: (i) chiral prolinol analogues, which obtain tetrahydrofuran‐fused 3,4‐dihydrocoumarins and 2,3,4‐trisubstituted tetrahydrofurans; (ii) chiral bifunctional squaramides, affording diverse spirocyclic frameworks such as spiro‐tetrahydrofuran‐pyrazolones, morpholinones, and oxindole‐derived systems; (iii) chiral bifunctional thioureas, which forms 1,3‐dioxolanes, oxazolidines, and cyclic acetals; (iv) multifunctional modular organocatalysts, affording enantioenriched α,β‐disubstituted γ‐butyrolactones and (v) other chiral organocatalysts which cannot be grouped in previous categories such as Song’s chiral oligoethylene glycol as a cation‐binding catalyst leads to the generation of chiral 1,4,2‐dioxazinanes.