Facile ring cleavage of basic azetidines

Azetidines containing a basic ring nitrogen atom have been shown to undergo facile ring cleavage to afford 3-halo-1-amino propane derivatives upon exposure to alkyl bromides and acyl chlorides under certain conditions. The rate of ring cleavage appears to be determined largely by the rate at which quaternization of the azetidine nitrogen atom occurs. Alkylation of NH azetidines to afford N-alkyl azetidines can be carried out in synthetically useful yields if reaction times are kept short. As the free base, azetidines may undergo spontaneous oligomerization with concomitant ring cleavage.