Preparation and Reactions of Trifluoromethanesulfonic Arenesulfonic Anhydrides

Since the anhydrides (3) are not stable in pure form, exact physical data cannot be given; their structure, however, is established unequivocally by 'H-NMR and by their reaction with arenes, yielding aryl sulfones ( 4 ) (Table 1). The extraordinary sulfonylating potential of the anhydrides ( 3 ) is apparent from the reaction with an arene as unreactive as chlorobenzene, which is sulfonylated in high yield even at 0 C (see Table 1). With sulfonyl halides, on the other hand, sulfonesare formed from arenes only at elevated temperature and in the presence of Friedel-Crafts catalystsl3I. The anhydrides (3) are thermolabile; in the absence of arenes which can be sulfonylated they decompose in various ways depending on the nature of R.