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].

Fig. 1.

The synthesis of the title molecule, I. (i) Methyl acrylate, MeOH, 25 °C, 12 h. (ii) Diethyl malonate, reflux, 6 h. (iii) NaH, cyclohexane/toluene, reflux. (iv) AcOH/H2O (30%, v/v).

Fig. 2.

Molecular structure of the title compound, with 50% probability level displacement ellipsoids for non-H atoms.

Fig. 3.

A chain of hydrogen-bonded molecules, along the screw axis parallel to [100].