First, we provided a survey of how the solvent influences the reaction (Figures 2) kinetics going through the two-TS mechanism (Figures and). For this, we took the gas-phase calculation of the reaction at the DLPNO-CCSD(T)/CBS//r 2 SCAN-3c level of theory and applied the recently developed Solv model, applied in SPT-V scheme. We have selected 28 of the most common laboratory solvents, ranging from nonpolar (hexane, carbon disulfide) to the most polar (water). The studied solvents span a substantial polarity range, allowing us to explore the polarity influence on the effective reaction barrier height. It was decided to use two well-established polarity descriptors: the relative dielectric constant and Reichardt's polarity parameters. The latter one was introduced by Reichardt et al in 1963 and since then has been extensively used for studies involving solvent polarity. The full list of the studied solvents, as well as the corresponding dielectric constant and Reichardt's parameter values, can be found in ESI. The correlations of the effective barrier heights (Equation ) with solvents' dielectric constants ε and Reichardt's E T parameters are shown in the Figure . The polarity of the solvent increases with increasing ε and E T , and as we can see from the results, the increase of the polarity of the solvent decreases the effective reaction barrier, making the reaction faster. It is worth noting that the effect of solvent polarity on the effective reaction barrier height is not dramatic since the maximum difference observed for water (the most polar solvent studied) is still less than 1 kcal/mol. It is consistent with the previously reported observations that the pericyclic reactions are not sensitive to solvent polarity due to the absence of significant degree of charge separation in a course of the reaction. ) for 42 solvents of various polarity. The gas-phase energies were computed at the DLPNO-CCSD(T)/CBS//r 2 SCAN-3c, while the free-energy correction for solvation was computed within Solv model applied in the SPT-V scheme. Sulfolane has been excluded from the correlation plot with E T (30) parameters since, to the best of our knowledge, no value for it has been reported in the literature so far. ) in benzene at DLPNO-CCSD(T)/CBS//r 2 SCAN-3c level of theory were the following. The original reaction's (Figure ) effective barrier is 12 kcal/mol, for SeO 2 as a catalyst, it is 3 kcal/mol, for SO 3 as a catalyst, the reaction in the same treatment is barrier-less. The colors of the atoms illustrate whether they initially belong to the reactant (blue) or catalyst (red).