The reactions conditions had to be carefully controlled; when the reaction was warmed to room temperature, chloride 49 was the exclusive product. In summary, we have shown that the ring-opening of aziridines by pendant sulfamates is a viable strategy for the preparation of vicinal diamines. Our reaction is compatible with both cis and trans di-substituted aziridines; unsubstituted, N-alkyl, and N-aryl sulfamates engaged effectively. In all cases examined, the cyclization reaction was perfectly regioselective and stereospecific. The product oxathiazinane heterocycles could be activated and ring-opened with a diverse range of