Ring-Opening Reactions Of N-Tosylaziridines In DMF Without Any Catalyst

Aziridines with ternary cycle structure are an important intermediate in organic synthesis.They can react with different nucleophiles and get a lot of amino compounds with functional groups. The compounds have all the time attracted many chemists’ and pharmacologists’ attention due to their unique structure which have a wide range of usages in organic synthesis and biological activity. Most of research reports about ring opening reactions using Lewis acid, Lewis base and other types of catalysts, which have remarkable catalytic effect. Although certain progress was achieved, there remains lots of problems, for example, the catalysts are expensive and unstable, incompatible with the products and the substrates, and the post-processing is too complex, and so on. So, it’s of great theoretical and practical significance to focus on the research to more cheap and efficient, more environment-friendly and higher atom economy.In this paper, we achieved the ring openings of aziridines with amines, sodium azide, sodium sulfide and sodium benzenesulfinate dihydrate in DMF solvent without any catalyst and obtained the corresponding 1,2-diamines, 1,2-azide amines, (3-bis(amino)thioethers and β-amino sulfones, respectively.In the ring openings of aziridines with amines, the reaction of N-tosylcyclohexylaziridine with aniline was selected as a standard reaction to optimize the reaction conditions.The temperature, dosage of solvent and material ratio influencing on the yield of reaction were investigated, respectively. The best reaction conditions were obtained as follows:reaction temperature 110 ℃, dosage of solvent 1 mL, the substrate material ratio of 1:2.0. After optimizing the conditions, the generality of the reaction was further researched. Besides, a variety of N-tosylaziridines and amines were extended and ideal yields were attained. So, the selected reaction conditions were of certain generality, however, in view of N-Tosylaziridines regioselectivity is not enough good. In the ring openings of aziridines with sodium azide, N-tosylcyclohexylaziridine with sodium azide was selected as the model reaction. When N-tosylcyclohexylaziridine was 0.2 mmol, the amount of sodium azide was 1.5 equiv., dosage of solvent DMF was 1 mL, the standard reaction yield could reach more than 99% in 30 minutes at room temperature. Expanding N-Tosylaziridine substrates to aromatic and aliphatic, moderate to good yields were obtained. To our delight, when sodium azide was replaced with sodium sulfide, the reaction were completed in a few minutes. To the best of our knowledge, the first ever ring openings of aziridines with sodium sulfide were described and the corresponding β-bis(amino)thioethers were provided. In addition, aliphatic N-Tosylaziridines were found to be suitable substrates and moderate to good yields were obtained about desired products.We also try to use benzenesulfinate dihydrate as nucleophile, but the scope of the reaction was tightly limited. Only cyclic N-Tosylaziridines were the most appropriate substrates under 50℃. In the whole experiment,59 substances including 23 kinds of new products were obtained, which were examined by 1H NMR,13C NMR and HRMS.We found that the ring openings of N-Tosylaziridines in DMF solvent has the following advantages:(1) DMF has been a wide range of applications in the ring openings of aziridines; (2) The reaction system is simple without any catalyst and less costly; (3) The reaction system is easier to operate with milder reaction conditions. Therefore, the research as a new method of ring openings of aziridines has certain practical value.