A Theoretical Study of The Silver-Catalyzed Olefination Reaction Of Aldehyde Using Siloxyalkenes

Abstract

The mechanism of the aldehyde olefination reaction at the level of theory MN12L/6-31G(d)/SSD in the gas phase and in the presence of the solvent dichloromethane (DCM) was investigated using the SMD and PCM methods at 296.15 K. Computational results indicate that the mechanism can occur alkyne or aldehyde activation (pathway 1 or pathway 2). Pathway 1 has two cases, 1a and 1b, related to spatial factors.  1a and 1b. Pathway 1a is thermodynamically by about ΔΔG = 5.3 kcal/mol and kinetically by about ΔE^# = 4.4 kcal/mol preferred compared to pathway 1b for the cycloaddition step. The lowest free energy barrier (ΔG = 11.9 kcal/mol) is attributed to pathway 2 compared to pathway 1a (ΔG = 22.7 kcal/mol). Solvent analysis using the SMD method showed that toluene lowers the free energy barrier by about 7.2 kcal/mol compared to the used solvent DCM experimentally. The effect of siloxyalkyne and aldehyde substituents was also studied. Nucleophilic and electrophilic indices confirm the local selectivity of the reaction, and non-covalent interaction indices indicate that the TS1 is more stable than the TS1a.