Synthesis, crystal structures, and Hirshfeld analysis of three hexa­hydro­quinoline derivatives

Three hexa­hydro­quinoline derivatives were synthesized and crystallized in an effort to study the structure–activity relationships of these calcium-channel antagonists. The derivatives are ethyl 4-(2-meth­oxy­phen­yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate, C(22)H(27)NO(4), (I), ethyl 4-(4-meth­oxy­phen­yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carb­ox­yl­ate, C(22)H(27)NO(4), (II), and ethyl 4-(3,4-di­hydroxy­phen­yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate, C(21)H(24)NO(5), (III). In these hexa­hydro­quinoline derivatives, 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 substituted phenyl group at the pseudo-axial position are retained. Hydrogen bonds are the main contributors to the packing of the mol­ecules in these crystals.