The [Ru(CO)(porphyrin)]-Catalyzed Synthesis of N-Aryl-2-vinylaziridines

[Ru(CO)(porphyrin)] complexes have been found to catalyze the direct aziridination of conjugated dienes by aryl azides with high chemoselectivity, to provide N-aryl-2-vinylaziridines. To determine the scope of the reaction, several hydrocarbons and azides were tested. The reactions between 2,3-dimethylbuta-1,3-diene and aryl azides bearing electron-withdrawing groups in the para or meta positions in their aryl moieties occur very efficiently in short times, while the selectivities of the aziridinations are governed by the steric hindrances of the double bonds, so lower yields are registered with sterically encumbered 1,4-disubstituted dienes, though it is worth noting that the aziridination of trans,trans-1,4-diphenylbuta-1,3-diene was stereospecific and that only one isomer was obtained. The aza-[3,3]-Claisen rearrangement of 2-isopropenyl-2-methyl-N-(4-nitrophenyl)aziridine to produce the corresponding 2,5-1H-benzo[b]azepine is also reported.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)