Some features of adding formaldehyde dimer to alkenes with formation of alkyl-substituted 1,3-dioxanes by the Prins reaction in the gas phase are studied at the MP2(fc)/6-31G(d,p) computational level. The structure of the transition states and key intermediates is revealed and thermochemical reaction parameters are determined. It is shown that 1,3-dioxanes are mostly formed from the π-complex obtained in the result of formaldehyde dimer interaction with alkenes without intermediate formation of a σ-complex. Here the transformation of π-cation can be considered as a pseudo synchronous process. The synchrony degree and activation energy are considerably determined by the presence of alkyl substituents at the double bond.
vol. 1013 , pp. 57-61

Some features of adding formaldehyde dimer to alkenes by Prins reaction with oxygen-containing heterocycles formation are studied at the MP2(fc)/6-31G(d) computational level. The structure of the transition states, key intermediates are established and thermochemical reaction parameters are determined. It is shown that this interaction in the gas phase or nonpolar media with 1,3-dioxanes formation is a single-stage pseudo synchronous syn-addition. Alkyl substituents at the double bond reduce activation energy. It is revealed that the hydrogenated pyrans formation by the Prins reaction is possible not only with the participation of formaldehyde monomers, but with its oligomers either. However, the activation energy of this reaction is higher than that of 1,3-dioxanes formation.
Vol. 110, pp. 41-52