Three methoxy-substituted diethyl 4-phenyl-2,6-dimethyl-1, 4-dihydropyridine-3,5-dicarboxylate compounds

Diethyl 4-(2,5-dimethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3, 5-dicarboxylate, C(21)H(27)NO(6), (I), diethyl 4-(3, 4-dimethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3, 5-dicarboxylate, C(21)H(27)NO(6), (II), and diethyl 2, 6-dimethyl-4-(3,4,5-trimethoxyphenyl)-1,4-dihydropyridine-3, 5-dicarboxylate, C(22)H(29)NO(7), (III), crystallize with hydrogen-bonding networks involving the H atom bonded to the N atom of the 1,4-dihydropyridine ring and carbonyl O atoms in (I) and (II). Unusually, (III) shows O atoms of methoxy groups serving as hydrogen-bond acceptors.