Evidence Suggesting the Occurrence of Cycloaddition Products in the Ion/Molecule Reactions of Suitably Substituted Allyl Cations and Olefins

Article abstract of DOI:10.1002/oms.1210150311

The ion/molecule reactions of allyl cations and 2-methoxyallyl cations with vinyl methyl ether, 1-chloro-2-ethoxyethene and 1,2-dimethoxyethene are discussed in terms of <2+3> cycloaddition reactions.Deuterium labelling of the cations has been used for the study of the reaction mechanisms.The appearance of various product ions in these ion/molecule reactions lead to the suggestion that in reactions of allyl cations with alkenes non-cyclic ⁺ product ions are formed preferentially, but that in reactions of 2-methoxyallyl cations with alkenes a significant part of the product ions are methoxycyclopentadienyl cations.These observations are ascribed to the stabilizing effect of the methoxy group with regard to the positive charge in the product ions.