A computational study on the acceleration of the Prins reaction by indium trichloride

The role of indium trichloride in the Prins reaction, which leads to the formation of a tetrahydropyran ring from an olefin and an aldehyde, is analysed through DFT calculations with the B3LYP functional on a model system defined by 3-buten-1-ol, formaldehyde and indium trichloride. Two different mechanisms are characterized through calculation of all the relevant intermediates and transition states, and one of them is found to be able to explain experimental data, with the higher energy barrier around 25 kcal mol(-1). The reasons why specifically indium trichloride, in contrast to more conventional acids, is particularly efficient in this process, are also analysed. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.