(2RS,4′RS)-3′-(3-Chloro-4-methoxyphenyl)-4′-phenyl-4′H-spiro[indene-2,5′-isoxazol]-1(3H)-one ethanol monosolvate

The title compound, C23H17ClN2O3·C2H6O, is the stoichiometric 1:1 ethanol solvate of a racemic reaction product, which forms a conglomerate. The refined Flack parameter of 0.36 (3) indicates racemic twinning. In the structure, molecules are linked into zigzag chains by a series of intermolecular N—H⋯O and O—H⋯O hydrogen bonds.

The title compound, C 23 H 17 ClN 2 O 3 ÁC 2 H 6 O, is the stoichiometric 1:1 ethanol solvate of a racemic reaction product, which forms a conglomerate. The refined Flack parameter of 0.36 (3) indicates racemic twinning. In the structure, molecules are linked into zigzag chains by a series of intermolecular N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds.  In general, the 1,3-dipolar cycloaddition of arylnitrile oxides with ethylenic dipolarophiles leads to the regioselective formation of isoxazolines so that the electron withdrawing substituent of the dipolarophile is connected to position 5 of the isoxazoline ring (Al Houari et al., 2010;Toth et al., 1999;El yazidi et al., 1994).

Related literature
The crystal structure shows that the carbonyl group is bonded to position 5 of the isoxazoline ring, and that the hydrogen atom in position 4 is situated on the same side of the ring as the carbonyl group. The structural study by X-rays is in perfect agreement with the results of IR, 1 H and 13 C NMR spectroscopic analysis.
The 1,3-dipolar cycloaddition gave the title compound as a racemic product. However, the crystallization process from ethanol resulted in the formation of a conglomerate in space group P2 1 2 1 2 1 .
In the crystal molecules are linked into zigzag chains by a series of intermolecular N-H···O and O-H···O hydrogenbonding interactions, where both the main and the solvent molecules take part (Table 1).
Experimental 4 mmol of (2Z)-2-benzylidene-1,2-dihydro-3H-indol-3-one and 4 mmol of 3-chloro-N-hydroxy-4-methoxybenzenecarboximidoyl chloride were dissolved in 30 ml of THF in a 100 ml flask equipped with a condenser. The reaction mixture was refluxed until the complete dissolution of the reagents, and then 1 ml of N,N-diethylethanamine was added to the reaction.
Monitoring the reaction by thin film chromatography revealed the formation of a single cycloaddition product. After filtration, the organic solution was evaporated under reduced pressure. The residue obtained was recrystallized from ethanol.

Refinement
The H atoms bound to C were treated as riding with their parent atoms [C-H distances are 0.93 Å for CH groups with U iso (H) = 1.2 U eq (C), and 0.97 Å for CH 3 groups with U iso (H) = 1.5 U eq (C). The nitrogen-and oxygen-bound H atoms were located in a difference Fourier map. The nitrogen-bound H atom was refined freely, while the H atom of the hydroxyl group was refined as an idealised rotating group and with U iso (H) = 1.5 U eq (O).

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.