Density Functional Theory Investigation of Substituent Effects on the Si−CO Bond in Silylamides: Insights into Base-Catalyzed Reaction Mechanisms

Silylamides have gained significant attention in recent years due to their potential applications in organic synthesis, catalysis, and materials science. One of their crucial applications lies in the protection of alcohols. However, the catalytic degradation of silylamides remains complex, and a comprehensive understanding of the underlying mechanisms is still lacking. Thus, theoretical studies are essential for unraveling the mechanism behind the catalytic degradation of silylamides and identifying the key steps involved in the reaction. In this study, we employed density functional theory (DFT) to investigate the catalytic degradation of silylamides, specially at their Si − CO connection. We examined the reaction of 12 different silylamides (R ₃ SiCONR’ ₂ , where R = H, Me, F, NO ₂ , and R’ H, Me, and Ph), each featuring different substituents on both the silicon and nitrogen atoms, with three diverse bases: ⁻ OH, ⁻ OCH ₃ , and ⁻ NH ₂ . From results, we obtained so far, reveal that degradation of silylamides with OH ⁻ leads to the formation of a silyl carboxylate ion and ammonia in one mechanism, while another mechanism involves the generation of an amino carboxylate ion and silicon hydride. Thermodynamically, in mechanism 1, the smallest energy gap between reactants and products was given when substituents were R = CH ₃ and R’=H (-12.6 kcal/mol). On the other hand, the highest energy gap was shown with substituents R = NO ₂ and R’=H (-136.9 kcal/mol). The bond dissociation energy analysis showed that it is easy to break Si–C bond rather than C–N bond. At the moment none of the studied reaction mechanisms are favorable at ambient conditions, as indicated by extremely high activation barriers. A further insight into this topic is necessary.