The 9-decalyl and related cations. V. Generation of cis- and trans-2-t-Butyl-9-decalyl cations through π-routes by acetolysis

Abstract

The synthesis and solvolytic behaviour (in buffered acetic acid) of 4- (5?-t-butylcyclohex-1'-enyl)but-1-yl p-nitrobenzenesulfonate (6) and 3- (cyclohex-1'-enylmethyl)-4,4-dimethylpentyl p-nitrobenzene-sulfonate (7) are described. Kinetic and product studies have shown that π-bond participation occurs in the acetolysis of both compounds. The rate enhancements, compared with saturated analogues, are c. 46 and 8290 for (6) and (7). The considerably greater rate enhancement observed for (7) is a manifestation of the 'gem-dialkyl' effect and is explained in terms of the effect of the t-butyl group on the conformations that the side chain might adopt.    

The acetolyses of (6) and (7) give rise to cyclized products (c. 97 and 100%) arising from both cis- and trans-2-t-butyl-9-decalyl cations (2) and (3). The compositions of the products, which also include compounds formed from the cis-cation (55) obtained by a 1,2-hydride shift in (2), show that (6) and (7) do not react via the same cationic species.    

Ion-pairs of an undefined nature are implicated in the reactions. Entirely consistent evidence was not obtained for the hypothesis that the counter-ion, behaving as a base, probably plays a significant role in olefin formation from the cis- and trans-cations (2) and (3) in ion- pairs that might be formed initially from (6) and (7).