Displacement of Activated Amino Groups. C,N- vs. N,S-Bond Cleavage in the Reaction of N-Alkyl-disulfonamides with Nucleophiles

Sodiumthiophenoxide and sodiumphenylselenide react with N-benzyl- and N-hexyl-di-p-toluenesulfonamides ( 1 and 2 ) via displacement at the C-atom to afford the corresponding organosulfides and selenides in yields of 68–96%. In contrast, sodium cyanide converts disulfonamides to monosulfonamides by attack on the S-atom. The different selectivities of phenylsulfide and selenide as compared to cyanide anions with respect to attack on the C- and S-atoms are rationalized on the grounds of the HSAB (hard and soft acids and bases) principle of Pearson.