Diethyl 7,7′-dichloro-4-oxo-4H-[1,4′-biquinoline]-3,3′-dicarboxylate

In the title compound, C24H18Cl2N2O5, the quinoline and quinolinone moieties are nearly perpendicular to each other, forming a dihedral angle of 82.36 (3)°. In the crystal, molecules form a halogen bond between a Cl atom of a quinolinone moiety and the N atom of the quinoline moiety of the inversion equivalent [Cl⋯N = 3.106 (3) Å]. The molecules also form two kinds of C—H⋯O hydrogen-bonded centrosymmetric inversion dimers, making chains along the c-axis direction which are further interlinked by the halogen bonds into layers parallel to the bc plane.

In the title compound, C 24 H 18 Cl 2 N 2 O 5 , the quinoline and quinolinone moieties are nearly perpendicular to each other, forming a dihedral angle of 82.36 (3) . In the crystal, molecules form a halogen bond between a Cl atom of a quinolinone moiety and the N atom of the quinoline moiety of the inversion equivalent [ClÁ Á ÁN = 3.106 (3) Å ]. The molecules also form two kinds of C-HÁ Á ÁO hydrogen-bonded centrosymmetric inversion dimers, making chains along the caxis direction which are further interlinked by the halogen bonds into layers parallel to the bc plane.
This work was partly supported by Grants-in-Aid (No. 24590141 to YI) for Scientific Research from the Japan Society for the Promotion of Science. We acknowledge the University of Shizuoka for instrumental support.
Supporting information for this paper is available from the IUCr electronic archives (Reference: LD2125).

Comment
4-Quinolones show inhibition not only to Gram negative and Gram positive bacteria, but also to human immunodeficiency virus (HIV). The inhibition to HIV is derived from their chelating ability to metal ions in the active site of metalloenzyme HIV integrase. According to our inhibitor design targeting metalloenzyme influenza virus RNA polymerase (Ishikawa & Fujii, 2011), we tried to synthesize a 4-quinolone derivative bearing a benzenesulfonyl group.
As shown in Fig.1, the C-N bond formation between the quinolinone and quinoline rings is confirmed. The chloroquinolinone and chloroquinoline moieties are nearly perpendicular to each other [dihedral angle = 97.64 (3)°]. In the crystal, the molecules are linked to each other to give dimers through halogen bond between the Cl atoms of the chloroquinolinone moieties and the N atoms of the chloroquinoline moieties of the inversion equivalents i [Cl1···N2 = 3.106 (3) Å, i: -x + 1, -y, -z + 1]. Two systems of C-H···O hydrogen-bonded dimers form chains along the c-axis, which are interlinked by the halogen bonds forming layers parallel to the bc plane, as shown in Fig.2. On the other hand, clear-cut ring-ring stacking interaction is not found. These findings are in contrast with those in the crystal packing of diethyl 4oxo-4H-[1,4′-biquinoline]-3,3′-dicarboxylate (Ishikawa & Yoshida, 2014).

Experimental
In a Schlenk tube under nitrogen atmosphere, the mixture of ethyl 7-chloro-4-oxo-1,4-dihydroquinoline-3-carboxylate (5.00 mmol), benzenesulfonyl chloride (5.00 mmol), K 2 CO 3 (10.0 mmol) in 10 ml of DMF were stirred at 130 °C overnight. After cooling to room temperature ice water was added. The precipitates were collected, and were   The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. Hydrogen atoms are shown as small spheres of arbitrary radius.   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.66 e Å −3 Δρ min = −0.95 e Å −3 Special details Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).