Abstract A procedure was developed for selective opening of the cis-2, 4, 5- triarylimidazoline ring to form erythro-1, 2-diamino-1, 2-diarylethane derivatives. These ring- opening products, erythro-ethylenediamine derivatives, can undergo quantitative isomerization to threo-ethylenediamine derivatives in the presence of strong bases in DMSO.
![N-[2-(benzylideneamino)-1,2-diphenylethyl]benzamide Structure](https://image.chemsrc.com/caspic/104/3190-22-5.png)