Synthesis, rearrangement and solvolysis of propargylic and allylic trifluoromethanesulfinates

The synthesis and reactivity of propargylic and allylic trifluoromethanesulfinates under various conditions has been investigated. Propargylic esters readily undergo [2,3]-sigmatropic rearrangement to the corresponding allenyl trifluoromethyl sulfones, even under solvolytic conditions. An unusually facile nucleophilic addition of the solvent to the allenyl sulfone under the latter conditions has also been observed. On the other hand, the reactivity of allylic esters strongly depends on substitution. Thus, while cinnamyl triflinate reacts by an ionic mechanism, the corresponding α-methylallyl ester reacts by a concerted pathway.