Molecular and crystal structures of 1-methyl-2-Oxo-3-acetoxy-4-hydroxy-4-(Phenyl)piperidine, 1-ethyl-2-oxo-3,4-dihydroxy-4-(Pyridyl)piperidine, and 1-benzyl-2-oxo-3,4-dihydroxy-4-(Pyridyl)piperidine and the role of hydrogen bonds in molecular packing in crystals

The molecular and crystal structures of 1-methyl-2-oxo-3-acetoxy-4-hydroxy-4-(phenyl)hydropyridine, 1-ethyl-2-oxo-3,4-dihydroxy-4-(pyridyl)piperidine, and 1-benzyl-2-oxo-3,4-dihydroxy-4-(pyridyl)piperidine are determined by X-ray diffraction analysis. These three hydroxy derivatives of hydropyridine are the convenient model compounds in studies of the influence of intramolecular and intermolecular hydrogen bonds on the conformation and packing of molecules in crystals. The molecules of hydroxy derivatives possess a considerable conformational flexibility and can form an extended network of intramolecular and intermolecular hydrogen bonds. It is shown that these compounds more often than others form noncentrosymmetric and polysystem crystals. The role of the molecular association and the type of hydrogen-bonded associates (syntons) in crystal packing are discussed.