Comparative Study of the Catalytic Activity of Hypervalent Halogen(III) and Chalcogen(IV) Salts in the Imine–Isocyanide Coupling

In this study, the catalytic activity of halonium and chalconium salts was explored, and special attention was focused on their application as σ-hole donating species in noncovalent organocatalysis. The catalytic performance of a series of halonium (Cl^III, Br^III, I^III) and chalconium (S^IV, Se^IV, Te^IV) salts was evaluated in the imine–isocyanide coupling, which is a key method for synthesizing biologically active compounds being one of the steps of Groebke–Blackburn–Bienaymé reaction. Analysis of the kinetic data obtained via utilization of ¹H NMR spectroscopy revealed that the iodine-based salt demonstrated the highest activity among the chosen halogen bond donors, while telluronium salt outperformed their sulfonium and selenonium counterparts in the chalcogen bond donating moiety.