Abstract: Based on the density functional theory (DFT), the Minnesota functional M06-2X method was employed to study the ring-opening reaction mechanism of (2S, 3S)-2-phenyl-1-((S)-1-phenylethyl)azetidin-3-amine reacting with phenylisothiocyanate or phenylisocyanate. The amine reacting with phenylisothiocyanate generates an intermediate, which then undergoes proton transfer. Subsequently, the sulfur atom conducts a nucleophilic attack on the C2 position of the four-membered ring to give dihydrothiazole after isomerization from a five-membered ring. The amine reacting with phenylisocyanate forms urea. Protic acid or copper trifluoromethanesulfonate is required when the four-membered ring of the urea undergoes a ring-opening reaction.

Key words: 3-Aminoazetidine; Ring opening reaction, Density functional theory, Reaction mechanism