rac-2-(2-Chloro-6-methylquinolin-3-yl)-2,3-dihydroquinolin-4(1H)-one

In the title compound, C19H15ClN2O, the quinoline ring forms a dihedral angle of 43.24 (1)° with the benzene ring of the dihydroquinolinyl system. In the crystal, molecules are linked through a single weak C—H⋯O hydrogen bond, forming ribbons which extend along (100), giving alternating zigzag molecular layers which stack down the b-axis direction.

In the title compound, C 19 H 15 ClN 2 O, the quinoline ring forms a dihedral angle of 43.24 (1) with the benzene ring of the dihydroquinolinyl system. In the crystal, molecules are linked through a single weak C-HÁ Á ÁO hydrogen bond, forming ribbons which extend along (100), giving alternating zigzag molecular layers which stack down the b-axis direction.
Convenient synthesis of 2-aminochalcone and its amide derivatives and the ready cyclization of these compounds to 2aryl-2,3-dihydroquinolin-4(1H)-ones have been widely explored (Varma & Saini, 1997;Donnelly & Farrell, 1990). Silica gel supported InCl 3 (20 mol %) is a new solid-support catalyst that can be used under solvent-free conditions for the facile and efficient isomerization of 2-aminochalcones to the corresponding 2-aryl-2,3-dihydroquinolin-4(1H)-ones (Hemanth Kumar et al., 2004). As a part of a program directed toward the synthesis of new suitably functionalized heterocyclic compounds of potential biological activity (Bouraiou et al., 2008(Bouraiou et al., , 2011Benzerka et al., 2011), we report herein the synthesis and structure determination of the title compound, C 19 H 15 ClN 2 O.
In the title compound ( Fig. 1), the quinoline ring forms a dihedral angle of 43.24 (1)° with the phenyl ring of the 2,3-dihydroquinolin-4(1H)-one moiety. The geometric parameters are in agreement with those of other structures possessing a quinolyl substituent, previously reported in the literature (Belfaitah et al., 2006;Benzerka et al., 2011). The crystal structure can be described as alterning zigzag ribbons which stack down the b axis of the unit cell ( Fig. 2), these ribbons comprising molecules linked through a single weak intermolecular C17-H···O1 hydrogen bond (Table 1), and extending down a (Fig. 3). The hetero N2-H2 group has no acceptor in the crystal structure.
Experimental 2-Aminoacetophenone (1mmol) was first condensed with 2-chloro-3-formyl-6-methylquinoline (2 mmol) to give the corresponding 2-aminochalcone in 74% yield, according to the procedure described by Gao et al. (1996). In the next step, a mixture of 2-aminochalcone (100 mg) and 1 g of silica gel impregnated with indium(III) chloride (20 mol%, 13.6 mg) was irradiated in a domestic microwave oven at 360 W for 5 minutes. Under these conditions, the title compound was successfully synthesized in good yield (69%). Single crystals suitable for the X-ray diffraction analysis were obtained by dissolving the compound in a diisopropyl ether/CHCl 3 solvent mixture and allowing the solution to slowly evaporate at room temperature.

Refinement
The N-bound H-atom (H2) was located in a difference-Fourier map and its positional parameters were refined isotropically. All other H atoms were introduced in calculated positions and treated as riding on their parent C atom, with C-H = 0.93, 0.96, 0.97 or 0.98 Å, with U iso (H) = 1.2 or 1.5 U eq (C). No H-bond acceptor could be located for the N2- and DIAMOND (Brandenburg & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figure 1
The structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.     Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.