title: Ethyl 8-meth-oxy-4-oxo-1,4-di-hydro-quinoline-3-carboxyl-ate.
abstract: In the title compound, C13H13NO4, the asymmetric unit contains four independent mol-ecules, each exhibiting an intra-molecular N-H⋯O hydrogen bond. The ethyl group in one of the four mol-ecules is disordered, with a refined occupancy ratio of 0.295 (16):0.705 (16). A face-to-face stacking inter-action is found between the benzene rings of the quinoline units of two of the mol-ecules [centroid-centroid distance = 3.541 (2) Å], which are sandwiched by the other two mol-ecules through N-H⋯O hydrogen bonding. In the crystal, the sandwiched mol-ecules are assembled via stacking inter-actions along the b-axis direction with their translation-symmetry equivalents [centroid-centroid distance = 3.529 (2) Å], and are further linked through N-H⋯O hydrogen bonding. The other two mol-ecules are linked via stacking inter-actions with their inversion-symmetry equivalents [centroid-centroid distances = 3.512 (3) and 3.716 (4) Å] and via N-H⋯O hydrogen bonding.
authors.affiliation: School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Nanako
authors.initials: N
authors.lastname: Yoshida