cis-8-Azabicyclo[5.2.0]nonan-9-one

The title compound, C8H13NO, with two chiral centres in the cis-junction between the beta-lactam and cycloheptane rings, crystallizes with an orthorhombic unit cell. The strain of the beta-lactam moiety forces the cycloheptane ring to assume a chair conformation characterized by CS symmetry, which is less stable by 1.4 kcal mol(-1) than the twist-chair form, built up around a twofold axis. The homochiral helices, maintained by N-H...O=C hydrogen bonds are organized in antiparallel, mode around the respective screw axes of the non-centrosymmetric space group P2(1)2(1)2(1), which means that the enantiomers resolve in crystal conglomerates.