Isotopic substitution in practice

In case (a), labelled secondary alkyl benzenesulfonates (alkyl = 2-adamantyl, 2-propyl, cyclopentyl, etc.) with 18-28% of lsO in the sulfonyl group were partially solvolysed in a range of solvents (SOH), and recovered unreacted alkyl benzenesulfonates were then subject to reductive cleavage of the O—S bond of the sulfonate ester [39]. For water as solvent, the 

Consideration of the energetics of the sequence suggested that an intermediate like 31 might accumulate to observable concentrations in reactions of the triazolinedione with reactive alkenes whose structural features disfavour the [1,5]-hydrogen shift and, indeed, 

---