Deprotection of Sulfonamides Under Acidic Conditions

Chemoselective acidic hydrolysis of sulfonamides with trifluoromethanesulfonic acid has been evaluated as a deprotection method and further extended to more complex synthetic applications. In contrast to conventional troublesome sulfonamide hydrolysis, a near-stoichiometric amount of acid was found to be sufficient to bring about efficient deprotection of various neutral or electron-deficient N-arylsulfonamides, whereas electron-rich substrates provided sulfonyl group migration products. The deprotection method developed is fully selective for N-arylsulfonamides, and the possibility to discriminate among various different sulfonamides is demonstrated.