rac-2-Methyl-3,4,5,6-tetrahydro-2H-2,6-methano-1,3-benzoxazocin-4-one

Abstract

The title compound, C12H13NO2, represents a conformationally restricted 2-pyridone analogue of 1,4-dihydropyridine-type calcium antagonists and was selected for a crystal structure determination in order to explore some aspects of drug-receptor interaction. In the molecule, two stereogenic centres are of opposite chirality, whereas a racemate occurs in the crystal. It was found that the formally aminic N atom of the heterocycle is essentially sp2-hybridized with the lone-pair electrons partially delocalized through conjugation with the adjacent carbonyl bond. As a result, the central pyridone ring assumes an unsymmetrical half-chair conformation. The critical 4-phenyl ring is fixed in a pseudo-axial and perpendicular orientation [dihedral angle 85.8 (1)°] with respect to the pyridone ring via an oxygen bridge. In the crystal a pair of centrosymmetric N—H...O hydrogen bonds connect molecules of opposite chirality into a dimer. The dimers are packed by hydrophobic van der Waals interactions.