Ethyl 3-(2-ethoxy-2-oxoethoxy)-6-(trifluoromethyl)furo[3,2-c]quinoline-2-carboxylate

In the title compound, C19H16F3NO6, a quinoline derivative featuring an annealated furan substituent, the mean planes of the carboxy substituents are at an angle of 74.3 (2)°. In the crystal, C—H⋯O contacts result in undulating chains along [110]. C—H⋯F contacts also occur. The shortest centroid–centroid distance between rings is 3.3376 (7) Å, involving two furan rings of neighbouring molecules.

The aromatic scaffold is essentially flat. The least-squares plane defined by all the non-hydrogen atoms (r.m.s. of all fitted atoms = 0.0175 Å) features the carbon atom bearing the trifluoromethyl group as the atom deviating most from this common plane by 0.029 (1) Å. The least-squares planes defined by the respective atoms of the phenyl moiety and the furane moiety intersect at an angle of 2.26 (6) ° while they enclose angles of 0.76 (5) ° and 1.51 (6) ° with the leastsquares plane defined by the atoms of the central heterocycle. The fluorine atoms of the trifluoromethyl group adopt a staggered conformation with respect to the nitrogen atom. The two carboxy substituents bonded to the furane system are orientated nearly perpendicular to each other with the least-squares planes defined by their respective atoms enclosing an angle of 74.3 (2) °. (Fig. 1).
In the crystal, C-H···O and C-H···F contacts are apparent whose range invariably falls by more than 0.2 Å below the sum of van-der-Waals radii of the atoms participating. While the former contacts are supported by the hydrogen atom in ortho position to the trifluoromethyl group as the donor and one of the double bonded oxygen atoms as the acceptor, the C-H···F contacts stem from one of the hydrogen atoms of a methylene group. Metrical parameters as well as information about the symmetry of these contacts are summarized in Table 1. In total, the molecules are connected to undulated chains along [1 1 0]. In terms of graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the descriptor for these contacts is R 2 2 (22)R 2 2 (24) on the unary level. The shortest intercentroid distance between two aromatic systems was measured at 3.3376 (7) Å and is apparent between two furane moieties in neighbouring molecules (Fig. 2).

Refinement
Carbon-bound H atoms were placed in calculated positions (C-H 0.95 Å for aromatic carbon atoms and C-H 0.99 Å for methylene groups) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C).
The H atoms of the methyl groups were allowed to rotate with a fixed angle around the C-C bond to best fit the experimental electron density (HFIX 137 in the SHELX program suite (Sheldrick, 2008)), with U(H) set to 1.5U eq (C).

Figure 1
The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level).