Vible-light-induced [3+2] Cycloaddition Of Aziridines And Alkenes

Five-membered nitrogen-containing heterocyclic compounds are widely present in biologically active natural molecules and drug molecules,and aziridine is an important synthetic building block for the synthesis of nitrogen-containing complex molecules in the history of organic synthesis,such as the synthesis of alkylamines,pyrrolidines,pyrrolidines,and oxazolidines.At present,the ring opening methods of aziridine mainly include acid catalysis,base catalysis,transition metal catalysis,and free radical ring opening.The main reaction types include nucleophilic ring opening addition and cycloaddition reactions.Among them,the acid/base catalyzed ring-opening reaction of aziridine has matured,but usually there will be acidic or basic solution remaining,which is not friendly to the environment,and the compatibility of some functional groups under acid/base catalysis is poor.A lot of research work on the ring-opening reaction of aziridine catalyzed by transition metals has also been reported.The compatibility of functional groups is better,but transition metals are still relatively expensive,which is not conducive to future development.At present,most of the radical ring-opening reactions of aziridine use the substituents on the ring to indirectly open the free radical to obtain nitrogen radical intermediates,which greatly limits the types of substrates.There are only a few reports of single-electron ringopening to obtain carbon radical intermediates,but these intermediates have a high application value in the synthesis of nitrogen-containing amines/heterocyclic compounds,so more developments can be used for nitrogen The catalytic system for the single-electron ring-opening reaction of propidium is of great significance.We developed a metal-free visible light and iodine species synergistically catalyzed the regioselective single-electron ring opening method of aziridine,and applied it to the [3+2]cycloaddition reaction of aziridine and alkene.We mainly investigated the iodine source,iodine source equivalent,solvent,concentration,temperature and other conditions,and finally we established the optimal reaction conditions: quantitative olefin,2.5 equiv aziridine as substrate,1.0equiv TBAI as catalyst,0.05 M NMP is the solvent,90 W blue light is the light source,the reaction temperature is 70-75 °C,and the reaction is 8 h under nitrogen atmosphere.Under optimal reaction conditions,we have achieved a series of [3+2] cycloaddition reactions of activated olefins and substituted aziridines with a yield of 46%-88%.