A new strategy for the chemoselective sulfonamide N-alkylation of sulfonyl ureas under neutral and mild conditions

An efficient and chemoselective sulfonamide N-alkylation of sulfonyl ureas is described. The sulfonyl urea derivatives, prepared in situ by the addition of an amine to an arylsulfonyl isocyanate, are selectively alkylated in excellent yields under neutral and mild conditions by treatment with trialkylphosphite–dimethyl acetylenedicarboxylate at ambient temperature.