Ramberg-Backlund rearrangement vs. β-Elimination of haloform from trichloro and trifluoromethyl sulfones

A new and convenient method for the preparation of trichloro and trifluoromethanesulfinates is described. These esters readily undergo rearrangement to the corresponding sulfones at room temperature, in high yields. In contrast to trichloromethyl sulfoxides which undergo base-induced β-elimination of chloroform to sulfines, the corresponding sulfones undergo an unusually facile Ramberg-Backlund rearrangement with formation of dichloromethylene products. Replacement of CCl₃ by CF₃ results in complete loss of reactivity, even under drastic basic conditions.