The effect of bromine scanning around the phenyl group of 4-phenylquinolone derivatives.

Three quinolone compounds were synthesized and crystallized in an effort to study the structure-activity relationship of these calcium-channel antagonists. In all three quinolones, viz. ethyl 4-(4-bromophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (I), ethyl 4-(3-bromophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (II), and ethyl 4-(2-bromophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, (III), all C21H24BrNO3, common structural features such as a flat boat conformation of the 1,4-dihydropyridine (1,4-DHP) ring, an envelope conformation of the fused cyclohexanone ring and a bromophenyl ring at the pseudo-axial position and orthogonal to the 1,4-DHP ring are retained. However, due to the different packing interactions in each compound, halogen bonds are observed in (I) and (III). Compound (III) crystallizes with two molecules in the asymmetric unit. All of the prepared derivatives satisfy the basic structural requirements to possess moderate activity as calcium-channel antagonists.

Diethyl 4-(biphenyl-4-yl)-2,6-dimethyl-1,4-di-hydro-pyridine-3,5-di-carboxyl-ate.

The title compound, C25H27NO4, has a flattened di-hydro-pyridine ring. The benzene and phenyl rings are synclinal to one another, forming a dihedral angle of 49.82 (8)°; the axis of the biphenyl rings makes an 81.05 (9)° angle to the plane of the di-hydro-pyridine ring. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into chain motifs running along the a-axis direction. The chains are cross-linked by C-H⋯O inter-actions, forming sheet motifs running slightly off the (110) plane, together with an intermolecular interaction between head-to tail biphenyl groups, thus making the whole crystal packing a three-dimensional network. Intra-molecular C-H⋯O hydrogen bonds are also observed.

Ethyl 3-(10-bromo-anthracen-9-yl)-5-methyl-1,2-oxazole-4-carboxyl-ate.

In the title compound, C21H16BrNO3, the mean planes of the anthracene tricycle and isoxazole ring are inclined to each other at a dihedral angle of 72.12 (7)°. The carb-oxy group is slightly out of the isoxazole mean plane, with a maximum deviation of 0.070 (5) Šfor the carbonyl O atom. In the crystal, pairs of weak C-H⋯O hydrogen bonds link the mol-ecules into dimers, and weak C-H⋯N inter-actions further link these dimers into corrugated layers parallel to the bc plane.