Stereoselective Dihalogenation of Alkynes to Access Enantioenriched Z -Vicinal Dihaloalkene Atropisomers

The stereoselective construction of Z-configured olefins remains a fundamental challenge in synthetic chemistry, particularly when additional stereogenic elements with high enantioselectivity are simultaneously introduced. Furthermore, vicinal dihaloalkenes are privileged scaffolds in organic and medicinal chemistry, and the traditional protocol for preparing vicinal dihaloalkenes relies on a halonium intermediate-mediated pathway and typically yields E-configured adducts. Herein, we report the catalytic stereoselective synthesis of enantioenriched Z-vicinal dihaloalkene atropisomers in high yields (up to 95%) with excellent enantioselectivity (up to 99%) and a Z/E ratio of more than 20:1. This transformation was achieved through an allene-mediated organocatalyzed assembly of readily available N-Bromosuccinimide (NBS) and acyl halides as halogenation reagents.