TfOH‐Catalyzed Domino Cycloisomerization/Hydrolytic Defluorination of 2,3‐Allenyl Perfluoroalkyl Ketones.

A unique TfOH-catalyzed domino cycloisomerization/hydrolytic defluorination reaction of easily available n-perfluoroalkyl allenones in the presence of H2O providing furanyl perfluoroalkyl ketones has been developed. The 18O-labelling experiments confirmed that the oxygen atom of the carbonyl group in the final products originates from water.