Computational study on the conversion of an aziridine and iminium salt to a 1,2-diamine

DFT calculations employing the SCRF-B3LYP/6-311+G(d) level of theory have been employed in order to quantitatively characterize the mechanism of the ring-opening reaction of (s)-1-benzyl-2-methyl-aziridine and an iminium salt to a 1,2-diamine, in the presence of lithium iodide. Computational results indicate that the optimal reaction pathway may proceed via an aziridinium cation intermediate mechanism, rather than by an SN2 mechanism. Self-consistent reaction field (SCRF) calculations, using the PCM model and THF as solvent, showed an energetic barrier for aziridine ring-opening to be on the order of ∼10.9 kcal/mol; indicating the process to be thermodynamically spontaneous. The catalytic role of I− and substituent effects are also elaborated upon herein.