Small-ring Compounds. XXIII. The Nature of the Intermediates in Carbonium Ion-type Interconversion Reactions of Cyclopropylcarbinyl, Cyclobutyl and Allylcarbinyl Derivatives

Investigation of the extent of isotope-position rearrangement in carbonium ion-type reactions of ^(14)C-labeled cyclopropylcarbinyl derivatives has revealed that the three methylene groups of the starting material achieve a striking degree of equivalence between reactants and products. These results, taken in conjunction with the abnormally large solvolytic reactivities of cyclopropylcarbinyl and cyclobutyl halides and sulfonate esters, can best be accounted for by assuming rapid but not instantaneous equilibration of three isomeric non-classical unsymmetrical “bicyclobutonium” ion intermediates