Re-Evaluating Chalcogen Bonding Trends: Catalytic Performance of Chaclonium(IV) Salts in the Povarov [4+2] Cycloaddition Reaction

This study investigates the catalytic activity of three chalconium salts Ar₃Ch⁺OTf^– (Ch = S^IV, Se^IV, Te^IV) in the Povarov [4+2] cycloaddition reaction of N-phenyl-1-(p-tolyl)methanimine and 2,3-dihydrofuran. Kinetic experiments revealed that, in contrast to the established trends, a sulfur-based catalyst (Cat1^OTf) displayed the highest activity, while selenium- and tellurium-based catalysts showed negligible activity. This unexpected outcome suggests that the imine activation may proceed via an alternative pathway, challenging traditional assumptions about the catalytic power of chalcogen bonding.