SYNTHESIS AND CATHODIC CLEAVAGE OF A SET OF SUBSTITUTED BENZENESULFONAMIDES INCLUDING THE CORRESPONDING TERT-BUTYL SULFONYLCARBAMATES - PKAOF SULFONAMIDES

From a series of Substituted benzenesulfonic acids, most of which have previously been employed for the protection of amino functions and in cluding a few such known to facilitate cleavage by acid, benzylamides 1a-k have been derived and studied. Initially their electrochemical cl eavage potentials were determined by cyclic voltammetry in order to fu rther explore selective deprotection within this substance group. In p arallel, the corresponding tert-butyl sulfonylcarbamates 2a-k have als o been prepared and studied. Among the sulfonamides investigated S-N b ond cleavage was found to take place over a wide range of potentials f rom -1.67 to -2.64 V (excluding the nitro derivative), the most acid-l abile groups requiring more negative potentials, whereas this cleavage was facilitated by 0.19-0.30 V for the sulfonylcarbamates. Small scal e electrolyses of 2 at controlled potential with determination of the cleavage products formed were subsequently performed. For the N-benzyl benzenesulfonamides 1, the pK(a)s in DMSO and in some cases also in wa ter have been determined and found to be in the range 14.0-16.4 and 10 .07-11.53, respectively.