Paliperidone: 3-{2-[4-(6-fluoro-1,2-benzoxazol-3-yl)piperidin-1-yl]ethyl}-9-hydroxy-2-methyl-1,6,7,8,9,9a-hexahydropyrido[1,2-a]pyrimidin-4-one

The title compound (also known as 9-hydroxyrisperidone), C23H27FN4O3, is a heterocyclic compound with manifold pharmacological properties. The hydroxy group shows disorder over two positions, with site-occupancy factors of 0.856 (2) and 0.144 (2). The piperidine ring adopts a chair conformation, while the annulated ring bearing the hydroxy group is present in a half-chair conformation. Classical O—H...O hydrogen bonds as well as C—H...N contacts connect the molecules into undulating sheets lying perpendicular to the crystallographic b axis. The shortest centroid–centroid distance between two centers of gravity is 3.5867 (8) Å and is apparent between the benzoxazole moiety and the six-membered ring bearing the keto substituent.