title: 4-Hy-droxy-1,1'-bis-[(S)-1-phenyl-eth-yl]-5,5',6,6'-tetra-hydro-3,4'-bipyridine-2,2'(1H,1'H)-dione.
abstract: The title bis-piperidine, C26H28N2O3, was unexpectedly obtained via a dimerization mechanism promoted by acetic acid when performing the Dieckmann cyclization of a chiral amido ester. The S,S configuration was assigned by reference to the enanti-omerically pure starting material. In the mol-ecule, two core heterocycles are linked by a σ bond. One ring includes a keto-enol group, while the other presents an enone functionality. Both rings present a conformation inter-mediate between envelope and screw-boat, and the dihedral angle between the mean planes passing through the rings [48.9 (1)°] is large enough to avoid hindrance between ring substituents. The enol tautomeric form in one ring favors the formation of strong inter-molecular O-H⋯O=C hydrogen bonds. The resulting one-dimensional supra-molecular structure features single-stranded helices running along the 21 screw axis parallel to [100].
authors.affiliation: Universidad Juárez Autónoma de Tabasco, División Académica de Ciencias Básicas, Km. 1 carretera Cunduacán, Jalpa de Méndez AP 24, Cunduacán, Tabasco, Mexico.
authors.forename: Nancy
authors.initials: N
authors.lastname: Romero
authors.forename: Dino
authors.initials: D
authors.lastname: Gnecco
authors.forename: Joel
authors.initials: J
authors.lastname: Terán
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bernès