Trifluoroacetic anhydride promoted Pummererrearrangement of γ-trifluoro-β-amino sulfoxides 1 follows an unusual pathway, in which a migration of the p-tolylthio group to the nitrogen atom provides the corresponding α-sulfenamidotrifluoroacetates 5. The usual removal of the proton in α to the sulfinyl moiety does not take place, as shown by maintenance of deuterium during the rearrangement. This procedure is exploited