On the azetidin-2-one ring formation. A 1H NMR investigation

Article abstract of DOI:10.1016/S0040-4020(01)89743-X

Azetidin-2-ones were prepared by addition of phenylacetic acid chloride to substituted benzal-anilines in DMF. The effect of temperature and substituents at the benzal-anilines on the reaction mechanism was investigated carrying out the reaction in DMF d₇ in an NMR probe of a Bruker 400-MHz spectrometer at 25 and 60°C. Proton signals, arising from two kinds of intermediates a 2-phenyl-N-(α-chlorobenzyl)-acetanilide (6) and a nitrogen-charged adduct (7) suggest that two competitive mechanisms play a role in the formation of trans and cis azetidin-2-ones.