Density function calculations (DFT) were performed with the Gaussian 16 program package . The structures of TS1 and INT1 were optimized in solvent under ωb97xd-SMD/def2-SVP level of theory for electron static effect and steric hindrance of triisopropylsilyl (TIPS) group make it very hard to load these five coordinated structures in the gas phase . The single point energy of TS1 and INT1 was corrected at ωb97xd(gas) /def2tzvpp level of theory, so: The other structural optimizations were performed under ωb97xd(gas)/def2-SVP level of theory. Single point energy was calculated at ωb97xd /def2tzvpp level of theory. Solvation calculations were carried out with SMD solvation model at ωb97xd/def2-SVP level of theory with dichloromethane (DCM, ε=8.93) as solvent. So, in this case, corrected Gibbs energy is: Our previous work has shown that this scheme is well suitable for evaluate reaction barrier of such system . Actually, 𝛥𝐺 def2𝑡𝑧𝑣𝑝𝑝 corr-sol 𝑆𝑀𝐷 is a good approximation of 𝛥𝐺 def2𝑡𝑧𝑣𝑝𝑝 sol . Vibrational frequency calculations were carried out at same level of theory as geometries optimization to verify that the optimized geometries are energy minimum or transition state and to provide thermal corrections for Gibbs free energies and enthalpies at 298.15 K in 1 atm. IRC calculation was performed for the key transition states to verify that the optimized transition states lead to correct structures . Optimized geometries were rendered with CYLView . The NCI analysis was carried out with Multiwfn and rendered with VMD . The electrophilicityω index and nucleophilicity N index is calculated with 33 ωb97xd/def2svp level of theory.