r.m.s. deviation of 0.0531 Å. The 1,4-dihydropyridine (1,4-DHP) ring adopts a slightly puckered boat-like conformation. The N and opposite C atoms deviate from the least-squares plane of the four other ring atoms by 0.039 (3) and 0.141 (3) Å, respectively. The C=O group located at the tricyclic fragment is fixed in an s-trans orientation, while the second C=O group adopts an s-cis orientation with respect to the double bonds of the 1,4-DHP ring. The pyridine ring has a pseudo-axial orientation with respect to the 1,4-DHP ring. The dihedral angle between the tricyclic system and the pyridine ring is 77.3 (3)°. In the crystal, the pyridine N atom accepts a hydrogen bond from the N - H group of the 1,4-DHP ring. The hydrogen bonds link the molecules into infinite C(8) chains along the b-axis direction.