6-Chloro-1-({[(2E)-2-methyl-3-phenylprop-2-en-1-yl]oxy}methyl)-1,2,3,4-tetrahydroquinazoline-2,4-dione

In the title compound, C19H17ClN2O3, the conformation about the ethylene bond [1.333 (2) Å] is E. The ten atoms comprising the quinazoline ring are essentially planar (r.m.s. deviation = 0.032 Å) and their mean plane forms a dihedral angle of 13.89 (7)° with the terminal phenyl ring; the molecule has an open conformation as these substituents are directed away from each other. In the crystal, centrosymmetrically related molecules are connected via N—H⋯O hydrogen bonds between the amide groups, leading to eight-membered {⋯HNCO}2 synthons. These are consolidated into a three-dimensional architecture by C—H⋯O, C—H⋯π and π–π interactions [ring centroid(N2C4)⋯centroid(C6) distance = 3.5820 (11) Å].

In the title compound, C 19 H 17 ClN 2 O 3 , the conformation about the ethylene bond [1.333 (2) Å ] is E. The ten atoms comprising the quinazoline ring are essentially planar (r.m.s. deviation = 0.032 Å ) and their mean plane forms a dihedral angle of 13.89 (7) with the terminal phenyl ring; the molecule has an open conformation as these substituents are directed away from each other. In the crystal, centrosymmetrically related molecules are connected via N-HÁ Á ÁO hydrogen bonds between the amide groups, leading to eight-membered {Á Á ÁHNCO} 2 synthons. These are consolidated into a threedimensional architecture by C-HÁ Á ÁO, C-HÁ Á Á andinteractions [ring centroid(N 2 C 4 )Á Á Ácentroid(C 6 ) distance = 3.5820 (11) Å ].
The financial support of the Deanship of Scientific Research and the Research Center of the College of Pharmacy, King Saud University is greatly appreciated. We also thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/12).  (Hopkins et al., 1996;Hopkins et al., 1999). In continuation to our interest in the chemistry of NNRTI's (El-Brollosy et al., 2008;El-Brollosy et al., 2009), we synthesized the title compound, 6chloro-1-[((E)-2-methyl-3-phenylallyloxy)methyl]quinazoline-2,4(1H,3H)-dione (I), as a potential NNRTI (El-Brollosy, 2007). Herein, we describe the results of its crystal structure determination and relate this to the structure of the recently determined methyl analogue (El-Brollosy et al., 2012).
In (I), Fig. 1, the conformation about the ethylene bond [C11═C13 = 1.333 (2) Å] is E. The 10 atoms comprising the quinazoline ring are planar with a r.m.s. = 0.032 Å; the maximum deviations from the least-squares plane = 0.051 (2) Å for the C1 atom and -0.046 (2) Å for the C2 atom. The dihedral angle between the fused ring system and the terminal phenyl ring of 13.89 (7)° is consistent with a twisted molecule; these substituents are directed away from each other so that the molecule has an open conformation. The torsion angle between the ethylene and phenyl rings, i.e. C11-C13-C14-C15, of 25.9 (3)° indicates a significant twist in this region of the molecule. However twisted the molecule of (I) is, it is less twisted than the methyl analogue where the dihedral angle between the quinazoline and phenyl rings was found to be 82.87 (7) Centrosymmetrically related molecules are connected via N-H···O hydrogen bonds between the amide groups (involving the carbonyl-O closest to the tertiary-N atom) and lead to eight-membered {···HNCO} 2 synthons, Table 1.
Experimental 6-Chloroquinazoline-2,4(1H,3H)-dione (0.197 g, 1 mmol) was stirred in dry acetonitrile (15 ml) under nitrogen and N,Obis(trimethylsilyl)acetamide (0.87 ml, 3.5 mmol) added. After a clear solution was obtained (10 min), the mixture was cooled to 223 K, and trimethylsilyl trifluoromethanesulfonate (0.18 ml, 1 mmol) was added followed by the drop wise addition of bis[(E)-2-methyl-3-phenylallyloxy]methane (0.616 g, 2 mmol). The reaction mixture was stirred at room temperature for 5 h. The reaction was quenched by the addition of saturated aq. NaHCO 3 solution (5 ml). The mixture was evaporated under reduced pressure and the residue was extracted with ether (3 × 50 ml). The combined ether fractions were collected, dried (MgSO 4 ) and evaporated under reduced pressure. The product was purified by silica gel column chromatography, using 20% ether in petroleum ether (40-60 °C), to afford the title compound as a white solid in 81% yield (0.288 g). Single crystals were achieved by crystallization from its ethanol solution (El-Brollosy, 2007

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H = 0.95 to 0.99 Å, U iso (H) = 1.2U eq (C)] and were included in the refinement in the riding model approximation. The amino H-atom was refined freely.

Figure 1
The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids 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.