Origin of Manipulating Selectivity in Prins Cyclization by [Ga₄L₆]^12– Supramolecular Catalysis through Host–Guest Interactions

Abstract

The host effect of the supramolecular [Ga4L6]12– tetrahedral metallocage on Prins cyclization reaction of the substrate by encapsulated citronellal has been investigated by means of molecular dynamics and quantum mechanics. The encapsulation process of the substrate into the [Ga4L6]12– cavity was simulated via attach–pull–release (APR) methods. Thermodynamic calculations and classical molecular dynamics simulations assessed the substrate’s microenvironment inside the cavity, guiding DFT-level modeling of the reaction. DFT calculations show diol product predominance in acidic solution but high enol selectivity inside [Ga4L6]12–, consistent with experimental findings. [Ga4L6]12– alters the selectivity of the Prins cyclization reaction by inhibiting diol formation. The activation strain model-based decomposition analysis (ASM-DA) of the barrier difference among distortion and interaction terms indicates that the more positive interaction between a host and guest in the diol transition state than enol determines the product selectivity, particularly the fewer C–H···O and O–H···O hydrogen-bonding interactions. These theoretical insights could contribute to a deeper understanding of the nature of supramolecular catalysis and to further develop new supramolecular catalysts.