Sulfonyl esters. 2. CS cleavage in some substitution reactions of nitrobenzenesulfonates

An attempt to explore aromatic sulfonate esters as agents for the condensation of alcohols with mercaptans revealed an unusual process for sulfonate esters: CS bond rupture. Two mechanistic possibilities for CS bond rupture are explored: (i) radical anion intermediacy via single electron transfer and (ii) nucleophilic aromatic substitution. Both experiments and molecular orbital computations are presented to support the conclusion that nucleophilic aromatic substitutions are occurring. Keywords: sulfonyl esters, nitrobenzenesulfonates, CS bond rupture.