The reaction of an azetidine with a chloroformate can give either the dealkylated heterocycle or the ring-opened product (gamma-chloroamine), which can further cyclize to the oxazinanone. A general study of this underrated reaction was conducted and revealed that azetidines can undergo smooth nucleophilic ring-opening reactions to highly functionalized gamma-chloroamines in the presence of a variety of alkyl chloroformates under mild reaction conditions. Yields are usually good, and parameters governing this reaction were evaluated.
Rearrangement of 2-Hydroxyalkylazetidines into 3-Fluoropyrrolidines
Upon treatment with DAST (diethylaminosulfur trifluoride) enantiopure 2-hydroxyalkylazetidines rearrange into 3-fluoropyrrolidines. The reaction is stereospecific and involves a bicyclic 1-azoniabicyclo[2.1.0]pentane intermediate which is regioselectively opened by a fluoride anion.