Nucleophilic Reactions at Tertiary Carbon. Part 3. σ- and π-routes to the 9-decalyl cation

The generation of the 9‐decalyl cation by solvolysis of cis‐ and trans‐9‐decalyl chloride (1) has been reinvestigated. The results of product, rate and isomerization studies implicate stereoisomeric ion pairs as intermediates, as in the case of the solvolysis of other stereoisomeric tertiary chlorides (Parts 1 and 2). On the other hand, both symmetrically and unsymmetrically solvated 9‐decalyl cations are indicated in the cyclization of 4‐(cyclohexen‐1‐yl)butyl tosylate. No evidence was obtained that conformational isomers of the 9‐decalyl cation play a role as product determining intermediates.