3-(6-Benzyloxy-2,2-dimethylperhydrofuro[2,3-d][1,3]dioxolan-5-yl)-5-(4-chlorophenyl)-4-nitro-2-phenyl-2,3,4,5-tetrahydroisoxazole

In the title compound, C29H29ClN2O7, the isoxazole and dioxolane rings adopt envelope conformations, and the furan ring adopts a twisted conformation. The crystal structure is stabilized by intermolecular C—H⋯π interactions between a benzyloxy methylene H atom and the 4-chlorophenyl ring of an adjacent molecule, and by weak non-classical intermolecular C—H⋯O hydrogen bonds. In addition, the crystal structure exhibits a Cl⋯O halogen bond of 3.111 (3) Å, with a nearly linear C—Cl⋯O angle of 160.7 (1)°.

In the title compound, C 29 H 29 ClN 2 O 7 , the isoxazole and dioxolane rings adopt envelope conformations, and the furan ring adopts a twisted conformation. The crystal structure is stabilized by intermolecular C-HÁ Á Á interactions between a benzyloxy methylene H atom and the 4-chlorophenyl ring of an adjacent molecule, and by weak non-classical intermolecular C-HÁ Á ÁO hydrogen bonds. In addition, the crystal structure exhibits a ClÁ Á ÁO halogen bond of 3.111 (3) Å , with a nearly linear C-ClÁ Á ÁO angle of 160.7 (1) .
The molecular packing is stabilized by weak non-classical intermolecular C-H···O hydrogen bonds (Table 1 and Fig. 2; symmetry code as in Fig. 2). Additionally, the crystal structure exhibits a Cl···O halogen bond (Politzer et al., 2007) between the chlorine atom and the oxygen of a neighbouring NO 2 group, with a Cl1···O2 iv distance of 3.111 (3) Å (symmetry code as in Fig. 2). The molecular packing (Fig. 3) is further stabilized by an intermolecular C-H···π interactions between the methylene H atom of benzyloxy substituent and the 4-chlorophenyl ring of an adjacent molecule, with a C21-H21···Cg1 iii separation of 2.75 Å (Table 1, Cg1 is the centroid of C1-C6 benzene ring).

Experimental
A mixture of D-glucose derived nitrone (0.5 mmol) and β-nitrostyrene (0.5 mmol) was refluxed in dry toluene (10 ml) until completion of the reaction as evidenced by TLC analysis. The solvent was evaporated under reduced pressure. The crude was purified by column chromatography on silica gel (Merck, 100-200 mesh, ethylacetate-petroleum ether (10 : 90) to afford pure isoxazolidine. Single crystals of the title compound suitable for X-ray diffraction was recrystallized from ethanol.

Refinement
All H atoms were positioned geometrically, with C-H = 0.93-0.98 Å and constrained to ride on their parent atoms, with U iso (H) = xU eq (C, N), where x = 1.5 for methyl H and x = 1.2 for all H atoms.  Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as a small spheres of arbitrary radius.

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.
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 > 2sigma(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.