Theoretical Investigation of the Mechanism of the Hock Rearrangement with InCl₃ as Catalyst**

The Hock rearrangement is an acid catalyzed reaction involving organic hydroperoxides and resulting in an oxidative cleavage of adjacent C−C bonds. It has significant industrial applications, like the production of phenol (cumene process), but it remains scarcely used in organic synthesis. In addition, its detailed mechanism has never been studied. Thus, we report herein a theoretical study of the Hock rearrangement, using InCl₃ as a Lewis acid catalyst. The aim of this work was to fully understand the mechanism of this fundamental reaction, and to rationalize the influence of the substrate electronic properties on the reaction outcome. Furthermore, the structure of the active indium(III) catalyst interacting with the peroxide substrate was investigated, revealing the co-existence of several energetically close reaction pathways. The coordinated monomeric form of the Lewis acid emerges as the most active catalyst compared to dimeric species. However, we show that In₂Cl₆ species coordinated to the substrate are central in this catalytic cycle, primarily serving as a reservoir of active monomeric species.