Ethyl 1-methyl-2-oxo-1,2-dihydroquinoline-4-carboxylate

The title compound, C13H13NO3, lies on a mirror plane with an intra­molecular C—H⋯O hydrogen bond enclosing an S(6) ring. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into zigzag chains along the a-axis direction and π–π inter­actions, with a centroid-to-centroid distance of 3.7003 (2) A, involving the pyridine and benzene rings of the oxo­quinoline ring system, pack the mol­ecules into parallel layers.


Structure description
Quinolone derivatives are a versatile class of nitrogen-containing heterocyclic compounds and they are useful intermediates in organic synthesis. They possess a broad spectrum of biological activities including anti-cancer (Elderfield & LeVon, 1960), antiinflammatory (Ratheesh et al., 2013) and antibacterial properties (Beena & Rawat, 2013;Chai et al., 2011). Some quinoline derivatives have also been reported as corrosion inhibitors for steel in an acidic medium (Ebenso et al. 2010). Following on from our research in the field of substituted pyrido[2,3-b]pyrazine derivatives (Filali Baba et al., 2016), we report here the synthesis of the title compound by the condensation reaction of iodomethane with ethyl 1,2-dihydro-2-oxoquinoline-4-carboxylate and its crystal structure.

Synthesis and crystallization
A solution of ethyl 1,2-dihydro-2-oxoquinoline-4-carboxylate (1 g 4.6 mmol) in 15 ml of DMF was mixed with iodomethane (0.34 ml, 5.5 mmol), K 2 CO 3 (0.82 g, 6 mmol) and TBAB(0.03 g, 0.1 mmol). The reaction mixture was stirred at room temperature in DMF for 6 h. After removal of salts by filtration, the DMF was evaporated under reduced pressure and the residue obtained was dissolved in dichloromethane. The organic phase was dried over Na 2 SO 4 then concentrated in vacuo. The title compound was obtained after recrystallization from a dichloromethane/hexane (1/3) solvent mixture, yield = 81%.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms on the C12 and C13 methyl groups were generated using the PART À1 and AFIX 137 functions in SHELXL.  Symmetry code: (i) x þ 1 2 ; Ày þ 1 2 ; Àz þ 1 2 .

Figure 1
The structure of the title compound, showing the atom-numbering scheme, with displacement ellipsoids drawn at the 30% probability level.

Figure 2
The packing of the title compound, viewed along the b axis. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.28 e Å −3 Δρ min = −0.15 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.