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

Diethyl 4-(2,5-dimethoxyphenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarb oxylate, C21H27NO6, (I), diethyl 4-(3,4-dimethoxyphenyl)-2,6-dimethyl-1,4-d ihydropyridine-3,5-di- carboxylate, C21H27NO6, (II), and diethyl 2,6-dimeth yl-4-(3,4,5-trimethoxyphenyl)-1,4-dihydropyridine-3,5-dicarboxylate, C22H29 NO7, (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 a s hydrogen-bond acceptors.