Cis-7-Azabicyclo[4.2.0]octan-8-one

Under the strain of the quasi-planar,B-lactam moiety, the rigid cyclohexane ring in the title compound, C7H11NO, can assume either a flexible boat form (77%) or a flexible half-chair form (23%). These two forms can be present simultaneously. The racemic crystals, isostructural with the cis-6-azabicyclo[3.2.0]heptan-7-one homologue [Reck et al. (1990). Acta Cryst. C46, 720-722], are characterized by N-H...O=C hydrogen bonds that are formed along the screw axes of the similar monoclinic unit cell.