The single-crystal X-ray structures of three oxidation products of 4-(
3-nitrophenyl)-1,4-dihydropyridine, namely, -ethoxycarbonyl-5-methoxyc
arbonyl-2,6-methyl-4-(3- nitrophenyl) pyridinium nitrate, C18H19N2O6+.
NO3-, dineopentyl ethyl-4-(3-nitrophenyl)pyridine-3,5-dicarboxylate, C
25H32N2O6, and dihexyl 2,6-dimethyl-4-(3-nitrophenyl)pyridine-3, ate,
C27H36N2O6, suggest that their decreased calcium-blocking activity ari
ses from incompatibility of the phenyl ring and ester conformation wit
h the receptor site.