A new class of carbamylating agents based on the cyclosulfamide scaffold is reported. These compounds were found to be efficient time-dependent inhibitors of human neutrophil elastase (HNE). Exploitation of the three sites of diversity present in the cyclosulfamide scaffold yielded compounds which inhibited HNE but not proteinase 3 (PR 3) or bovine trypsin. The findings reported herein suggest that the introduction of appropriate recognition elements into the cyclosulfamide scaffold may lead to highly selective agents of potential value in the design of activity-based probes suitable for investigating proteases associated with the pathogenesis of chronic obstructive pulmonary disease.