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 intramol ecular and intermolecular hydrogen bonds on the conformation and packing of molecules in crystals. The molecules of hydroxy derivatives possess a cons iderable conformational flexibility and can form an extended network of int ramolecular and intermolecular hydrogen bonds. It is shown that these compo unds more often than others form noncentrosymmetric and poly-system crystal s. The role of the molecular association and the type of hydrogen-bonded as sociates (syntons) in crystal packing are discussed. (C) 2000 MAIK "Nauka/I nterperiodica".