Observation of Solvent Enantio-Isotope Effect in Asymmetric Ring-Opening of Cyclic Diaryliodoniums with Selenocyanate

Abstract

A Cu-catalyzed asymmetric coupling reaction between cyclic diaryliodoniums and the ambident nucleophile KSeCN was reported. Utilizing water as a co-solvent (CH₂Cl₂/H₂O) achieves high chemoselectivity by forming a nitrogen-hydrogen-bond, thereby blocking the N-site of ambident NCSe^- species, thus realizing efficient C-Se coupling. In contrast to the well-known kinetic isotope effect used to evaluate whether the C-H/D bond cleavage is rate-determining, the influence of deuterium-containing solvents on enantioselectivity remained largely unexplored. In this reaction, we observed a notable enhancement in enantioselectivity upon replacing H₂O with D₂O.