Two 1,4-dihydropyridine derivatives with potential calcium-channel antagonist activity

The title compounds, benzyl 4-(3-chloro-2-fluorophenyl)-2-methyl-5-oxo-4,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carboxylate, C(23)H(19)ClFNO(3), (I), and 3-pyridylmethyl 4-[2-fluoro-3-(trifluoromethyl)phenyl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C(26)H(24)F(4)N(2)O(3), (II), belong to a class of 1,4-dihydropyridines whose members sometimes display calcium modulatory properties. The 1,4-dihydropyridine ring in each structure has a shallower than usual shallow-boat conformation and is nearly planar in (I). In each structure, the halogen-substituted benzene ring is oriented such that the halogen substituents are in a synperiplanar orientation with respect to the 1,4-dihydropyridine ring plane. The oxocyclopentene ring in (I) is planar, while the oxocyclohexene ring in (II) has a half-chair conformation, which is less commonly observed than the envelope conformation usually found in related compounds. In (I), the frequently observed intermolecular N-H···O hydrogen bond between the amine group and the carbonyl O atom of the oxocyclopentene ring of a neighbouring molecule links the molecules into extended chains; there are no other significant intermolecular interactions. By contrast, the amine group in (II) forms an N-H···N hydrogen bond with the pyridine ring N atom of a neighbouring molecule. Additional C-H···O interactions complete a two-dimensional hydrogen-bonded network. The halogen-substituted benzene ring has a weak intramolecular π-π interaction with the pyridine ring. A stronger π-π interaction occurs between the 1,4-dihydropyridine rings of centrosymmetrically related molecules.