Computational Study of Hypervalent Chalcogen Bond Catalysis on the Hydroarylation of Styrene with Phenol: O-Activation vs π-Activation.

Chalcogen bond catalysis is gaining recognition in organocatalysis due to its environmental benignity and relatively low cost. The hypervalent selenium salts can drive the hydroarylation of styrene and phenol, and hypervalent chalcogen···π catalysis has been proposed [Zhang, Q. Angew. Chem., Int. Ed. 2022, 61, e202208009]. In this work, the hydroarylation of styrene and phenol catalyzed by cyclic hypervalent selenium-based catalysts is investigated by density functional theory (DFT) calculations, and two activation modes are observed: one is on the styrene (π-activation mode), and the other is on the phenol (O-activation mode). The energy barriers via the O-activation mode are lower than those of the π-activation mode, and our proposed O-activation mode in this work may be more favorable. For the O-activation mode, energy barriers for the ortho-hydroarylation are lower than those for the para-hydroarylation, which is consistent with the experimental observation that the ortho-hydroarylation product is the major product and supports our proposed O-activation mode. Further investigation revealed that the stronger electrostatic interaction is the main factor leading to the ortho-hydroarylation in the O-activation mode compared to the para-hydroarylation. Moreover, the substituent effect of cyclic hypervalent selenium-based catalysts on the reactivity was investigated. This work would provide a valuable perspective on expanding applications for chalcogen bond catalysis.