Neighboring Carbon and Hydrogen. X. Solvolysis of Endo-Norbornyl Arylsulfonates.

摘要

Solvolysis of endo-norbornyl arylsulfonates proceeds in glacial acetic acid, aqueous acetone and aqueous dioxane to give completely the corresponding exo-derivative. That this endo to exo change involves rearrangement is clear from the complete resolution of endo-norbornyl alcohol and the solvolysis of optically active endo-norbornyl p-bromobenzenesulfonate in glacial acetic acid, ethanol and 75% aqueous acetone. Nearly complete loss of activity attends the formation of exo-products, first-order polarimetric rate constants agreeing with titrimetric rate constants within experimental error. The facts are most simply explained with carbon migration in the norbornyl cation. While the geometry in the endo-norbornyl p- bromobenzenesulfonate is unfavorable to participation of the C1-C5 bonding electron cloud in the ionization process, ionization is, for the most part, followed by rearrangement to the presumably more stable bridged structure. Solvent intervention, with 7-8% inversion, competes with carbon migration in acetolysis. jg. p.2.