Solvolytic fragmentation studies on 7-substituted exo- and endo-5,6-(o-phenylene)-2-norbornyl toluene-p-sulphonates

Abstract

Toluene-p-sulphonates (3)–(12) have been prepared and their rates and products of solvolysis in acetic acid studied. Enhanced solvolysis rates were found for (4) and (6) which, together with exclusive formation of fragmentation product, are explained in terms of a synchronous fragmentation process. The effect of non-bonded interactions on the alignment of participating bonds has been suggested to be important. Neighbouring-group participation has been demonstrated in reaction of (10) but free rotation of the C–OMe bond makes a synchronous process unimportant. Although some fragmentation product is formed in solvolysis of (3), (5), (9), (11), and (12), the presence of other products, and absence of enhanced solvolysis rates establishes the mechanism as ionisation to a carbonium ion, followed by fragmentation mainly due to relief of strain. No fragmentation was observed in solvolysis of (7) and (8) but interesting rearrangements involving the carbon–sulphur bond are observed.