Weakening of Amide Conjugation with a Nitrogen Atom Included in a Four Membered Ring.

The barriers to amide rotation about the N-N bond in 1-nitrosoazetidine, dimethylnitrosamine, 1-formylazetidine, 1,1′-carbonylbisazetidine, 1-dimethylcarbamoylazetidine, and dimethylformamide were measured by dynamic NMR spectroscopy. 1,1′-Carbonylbisazetidine and 1-dimethylcarbamoylazetidine, the structures of which were confirmed by data from the PMR and 13C NMR spectra, were obtained.