Duncan Nathan S, Beall Howard D, Kearns Alison K, Li Chun, Natale Nicholas R
Department of Pharmaceutical & Biomedical Science, The University of Montana, 32 Campus Drive, Missoula, MT 59812, USA.
Department of Chemistry, Ithaca College, 953 Danby Road, Ithaca, NY, 14850, USA.
Acta Crystallogr Sect E Struct Rep Online. 2014 Feb 19;70(Pt 3):o315-6. doi: 10.1107/S1600536814003080. eCollection 2014 Mar 1.
The asymmetric unit of the title compound, C21H16ClNO4, contains two independent mol-ecules (A and B), each adopting a conformation wherein the isoxazole ring is roughly orthogonal to the anthrone ring. The dihedral angle between the mean plane of the isoxazole (all atoms) and the mean plane of the anthrone (all atoms) is 88.48 (3)° in one mol-ecule and 89.92 (4)° in the other. The ester is almost coplanar with the isoxazole ring, with mean-plane dihedral angles of 2.48 (15) and 8.62 (5)°. In both mol-ecules, the distance between the ester carbonyl O atom and the anthrone ketone C atom is about 3.3 Å. The anthrone ring is virtually planar (r.m.s. deviations of 0.070 and 0.065 Å) and adopts a shallow boat conformation in each mol-ecule, as evidenced by the sum of the six intra-B-ring torsion angles [41.43 (15) and 34.38 (15)° for molecules A and B, respectively]. The closest separation between the benzene moieties of anthrones A and B is 5.1162 (7) Å, with an angle of 57.98 (5)°, consistent with an edge-to-face π-stacking inter-action. In the crystal, weak C-H⋯O and C-H⋯N inter-actions link the mol-ecules, forming a three-dimensional network.
标题化合物C21H16ClNO4的不对称单元包含两个独立的分子（A和B），每个分子都采用一种构象，其中异恶唑环与蒽酮环大致正交。在一个分子中，异恶唑（所有原子）平均平面与蒽酮（所有原子）平均平面之间的二面角为88.48 (3)°，在另一个分子中为89.92 (4)°。酯基几乎与异恶唑环共平面，平均平面二面角分别为2.48 (15)°和8.62 (5)°。在两个分子中，酯羰基O原子与蒽酮酮C原子之间的距离约为3.3 Å。蒽酮环实际上是平面的（均方根偏差分别为0.070和0.065 Å），并且在每个分子中都采用浅船式构象，这由六个B环内扭转角的总和[分子A和B分别为41.43 (15)°和34.38 (15)°]证明。蒽酮A和B的苯环部分之间的最近距离为5.1162 (7) Å，角度为57.98 (5)°，符合边对面π堆积相互作用。在晶体中，弱的C-H⋯O和C-H⋯N相互作用连接分子，形成三维网络。
