β-Sultams show extraordinary rate enhancements of 10 9 -and 10 7 -fold, respectively, compared with the acid-and base-catalyzed hydrolysis of corresponding acyclic sulfonamides. They are about 10 3 -fold more reactive than analogous β-lactams. The alkaline hydrolysis of some β-sultams shows a rate term that is secondorder in hydroxide ion concentration, which is indicative of a stepwise mechanism involving a trigonal bipyramidal intermediate (TBPI). The Brønsted β lg value for the alkaline hydrolysis of N-aryl-β-sultams is -0.58 and the kinetic solvent isotope effect k OHfor N-alkyl-β-sultams is 1.55, indicative of rate-limiting breakdown of the TBPI. The acid-catalyzed hydrolysis of β-sultams is strongly retarded by electron-withdrawing groups R to the sulfonyl group, and it is suggested that the mechanism may involve unimolecular ring opening to generate a sulfonylium ion. The Brønsted β lg value for the acid-catalyzed hydrolysis of N-benzyl-β-sultams is 0.32. The generalacid-catalyzed hydrolysis of N-benzyl-β-sultam by carboxylic acids shows a Brønsted R value of 0.67 and is attributed to a specific acid-nucleophilic mechanism with the formation of a mixed-anhydride intermediate.

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