A theoretical investigation of the reaction mechanism for hydrogenated furan formation under Prins reaction conditions in trifluoroacetic acid medium

The formation mechanism of hydrogenated furans by coupling between terminal alkenes and aldehydes in trifluoroacetic acid medium were investigated by ab initio calculations, the main attention was focused on the study of the rate controlling step. Two possible mechanisms for this reaction involving unsaturated alkoxycarbenium ions or dioxolenium ions as a key intermediate were considered. It was shown that the mechanism of formation of 3-alkylsubstituted hydrogenated furans in trifluoroacetic acid under Prins reaction conditions preferably includes recyclization of 3-(2-hydroxyethyl)-1-trifluoromethyl-2,5-dioxolenium ions.