The N-benzoyl derivatives of 2-oxa-5-azabicyclo [2.2. 1] heptane (7) and of 2-oxa-5- azabicyclo [2.2. 1] heptane-3-one (8) have been prepared from hydroxy-L-proline. The NMR spectra of these compounds have been analyzed with the aid of variable temperature studies. It was found that ΔG‡ for N CO rotation in 7 is≈ 2 Kcal/mole higher than for 8. Possible explanations for the difference in ΔG‡ are discussed.