Recent Advances in Catalytic Asymmetric Syntheses of Functionalized Heterocycles via Halogenation/Chalcogenation of Carbon-Carbon Unsaturated Bonds

Halogen (fluorine, chlorine, bromine, iodine) or chalcogen (sulfur, selenium)-containing heterocycles are widely recognized as key building blocks in many natural products and bioactive targets. Catalytic asymmetric halogenation/chalcogenation of carbon-carbon unsaturated bonds via onium ion transformations are efficient methods to obtain diverse chiral heterocyclic backbones. In the past few years, catalytic enantioselective versions of halo/thio/seleno-functionalizations with various halogen and chalcogen electrophiles have experienced constant development. This review highlights those advances in preparing functionalized heterocycles promoted by chiral organocatalysts or metal-based catalysts.