1-Benzyloxy-4-(2-nitroethenyl)benzene

The title compound, C15H13NO3, crystallizes with three independent molecules per asymmetric unit (Z′ = 3). One of these molecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.31 (12)° with 84.22 (12)°]. There are also differences in the number and nature of the weak intermolecular C—H⋯O contacts formed by each of the three molecules.

The title compound, C 15 H 13 NO 3 , crystallizes with three independent molecules per asymmetric unit (Z 0 = 3). One of these molecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.31 (12) with 84.22 (12) ]. There are also differences in the number and nature of the weak intermolecular C-HÁ Á ÁO contacts formed by each of the three molecules.

Comment
One of the most serious threats to human health today is acquired immunodeficiency syndrome, AIDS (UNAIDS/WHO, 2009). Most drugs used in AIDS treatment target the HIV-1 reverse transcriptase (RT). A class of compounds known as non-nucleoside reverse transcriptase inhibitors (NNRTIs) inhibits the ability of RT to transcribe by altering its structural and dynamic properties (Jones et al., 2006). In our research, (Hunter et al., 2008;Younis et al., 2010) N-[4-(2-prop-2-ynyloxyphenyl)ethyl]-N'-[2-(5-bromopyridyl)]thiourea, a phenylethylthiazolylthiourea analogue was the target NNRTI compound, using 4-hydroxy benzaldehyde as the starting material. In this paper, the crystal structure of a synthon of the target compound, namely 2-(4-benzyloxyphenyl)-1-nitroethene, is described as determined by x-ray diffraction.
The sample was recrystallized several times, and data collected from numerous crystals. Non-single-crystal samples were common and data quality tended to be low, however all data collections were consistant with that of the best quality structure found, as described below. The title compound was found to exist as discrete molecules (Figure 1), although there are some non-classical hydrogen bonding C-H···O interactions involving nitro and ether O atoms and H atoms from sp 2 aromatic and vinylic C atoms, see Table 1. Unlike related compounds, the CH 2 atoms do not act as hydrogen bond donors (Gerkin, 1999;Kennedy et al., 2010). The asymmetric unit contains three independent molecules ( Figure 2). Two have similar configurations but the third, that with C atoms numbered C16 through to C30, is somewhat more twisted. This is shown by the angle between the least squares planes of the aromatic rings (compare 70.26 (13) and 72.31 (12) with 84.22 (12)°) . Related vinyl substituted benzyloxyphenyl species are known to have both twisted (Wang et al., 2007;Zheng et al., 2008) and planar conformations (Gao et al., 2008;Stomberg & Lundquist, 1994) but in all cases, including the title complex, the vinyl group is coplanar with the attached aromatic ring. The three crystallographically independent molecules also differ from one another in the nature and number of their intermolecular contacts, Table 1. However, bond lengths and angles are in good agreement between the different configurations and with the related literature species.

Experimental
All reactions in the preparation of 2-(4-benzyloxyphenyl)-1-nitroethene were performed under an atmosphere of nitrogen gas. 3.85 g, (18.16 mmol) of 4-benzyloxybenzaldehyde and 1.22 g of ammonium acetate (15.80 mmol) in nitromethane (100 ml) were heated at 343 K for 9 h. The solution was cooled and diluted with dichloromethane (54 ml), then washed with two 200 ml portions of saturated sodium chloride solution and then washed with of 200 ml distilled water. The resulting solution was dried over anhydrous magnesium sulfate and the solvent evaporated to dryness under reduced pressure. Recrystallization of the crude produce from ethanol gave yellow crystals (3.84 g, 83%), Mp: 387-388 K.

Refinement
All H atoms were placed in calculated positions and refined in riding modes with U iso (H) = 1.2U eq (C). C-H distances 0.95 and 0.99 Å for CH and CH 2 respectively.