Quantum study of the silver-catalyzed [2+2] Intermolecular Cycloaddition Reaction of siloxyalkynes with α,β- unsaturated ketones
Keywords:
[2+2] cycloaddition, unsaturated ketones, siloxyalkynes, density subordination theory (DFT), solution method based on density (SMD).Abstract
The silver-catalyzed [2+2] cyclization reaction mechanism of siloxyalkynes with α,β unsaturated ketones was investigated at the level of theory MN12L/SVP-TZVP in the gas phase and with the SMD method in the presence of the solvent dichloromethane (DCM). results indicate that the mechanism can occur via alkyne or ketone activation (pathway 1 or pathway 2). Each pathway has two cases a and b related to spatial factors. Pathway 2a was found to have a lower free energy barrier than pathway 1a
(ΔG = 2.5 kcal/mol), and a similarly lower free activation energy (ΔE# = 5.8 kcal/mol). Furthermore, it was observed that toluene reduces the free energy barrier by about
(8.1 kcal/mol) compared to the solvent DCM, making it the most suitable solvent. The effect of the substituents of both alkyne and ketone was also studied. Analysis of nucleophilic and electrophilic indices confirms the regioselectivity of the reaction, and analysis of non-covalent interaction indices indicate that the TS2a is more stable than the TS1a.
