The pathways for the cis-to-trans isomerization of 1,1,3-trimethyl-2-phenylsilacyclobutane and the CO2 insertion into 2-arylsilacyclobutane and naphthosilacyclobutene are analyzed using density functional theory computations. The proposed mechanisms to explain both isomerization and CO2 insertion were originally based on the formation of a carbanion resulting from the ring opening of 2-arylsilacyclobutanes dissolved in a polar aprotic solvent. Such latent carbanionic species yield the respective silalactones by reacting with CO2. We found concerted mechanisms competing with slightly more viable stepwise mechanisms involving metastable carbanionic species. Moreover, we studied the incorporation of CO2 into silacycloalkanes with three-, four-, and five-membered rings, clearly identifying that the polar aprotic solvent effects, the phenyl group at 2-position whose role is explained in detail, and mainly the ring strain, as the driving force, are favoring factors in these reactions.

Mechanistic Study on CO2 Capture Using 2-arylsilacycloalkanes: The role of ring strain

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