Aromatic 4-Tetrahydropyranyl and 4-Quinuclidinyl Cations. Linking Prins with Cope and Grob

Abstract
The chair 4-tetrahydropyranyl cation and the 4-quinuclidinyl cation are shown to be energy minima and to be delocalized, with exceptionally long CH2CH2 bonds, according to B3LYP/6-31G* calculations; the implications for Prins cyclizations, Cope rearrangements, and Grob fragmentations are discussed.