Zirconium Lewis acid sites grafted onto a mesoporous silicate (MCM-41) and zirconium sites incorporated into inorganic–organic MOF materials are employed successfully in the rearrangement of β-pinene epoxide into myrtanal, which is a relevant compound for the fragrance industry. The materials are characterized and the strength of the active sites is evaluated by in situ IR spectroscopy with cyclohexanone as a probe molecule. It is shown that besides isolated zirconium sites, zirconium–oxygen–zirconium species might also be active species for the rearrangement.