103020-62-8Relevant articles and documents
Reactivity and mechanism in the hydrolysis of β-sultams
Baxter, Nicholas J.,Rigoreau, Laurent J. M.,Laws, Andrew P.,Page, Michael I.
, p. 3375 - 3385 (2007/10/03)
β-Sultams show extraordinary rate enhancements of 109-and 107-fold, respectively, compared with the acid-and base-catalyzed hydrolysis of corresponding acyclic sulfonamides. They are about 103-fold more reactive than analogous β-lactams. The alkaline hydrolysis of some β-sultams shows a rate term that is second-order in hydroxide ion concentration, which is indicative of a stepwise mechanism involving a trigonal bipyramidal intermediate (TBPI). The Bronsted βlg value for the alkaline hydrolysis of N-aryl-β-sultams is -0.58 and the kinetic solvent isotope effect kH2OOH/kD2OOD is 0.60, compatible with rate-limiting formation of the TBPI. Conversely, kH2OOH/kD2OOD for 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 α to the sulfonyl group, and it is suggested that the mechanism may involve unimolecular ring opening to generate a sulfonylium ion. The Bronsted βlg value for the acid-catalyzed hydrolysis of N-benzyl-β-sultams is 0.32. The general-acid-catalyzed hydrolysis of N-benzyl-β-sultam by carboxylic acids shows a Bronsted α value of 0.67 and is attributed to a specific acid-nucleophilic mechanism with the formation of a mixed-anhydride intermediate.
