3-exo-Chloro-8-oxabicyclo[3.2.1]oct-6-ene-2,4-diol chloroform 0.33-solvate

The title compound, 3C7H9ClO3·CHCl3, crystallizes with molecules of 3-exo-chloro-8-oxabicyclo[3.2.1]oct-6-ene-2,4-diol (A) and chloroform in a 3:1 ratio, in the space group R3m. Molecules of A straddle a crystallographic mirror plane, whereas the chloroform molecules (C and H atoms) lie additionally on the threefold axis. The molecules of A are linked into right- and left-helical chains by means of O—H⋯O hydrogen bonds, thus forming columns running along the c axis. Six interpenetrated columns form a channel in which the solvent molecules (chloroform) are located.

The title compound, 3C 7 H 9 ClO 3 ÁCHCl 3 , crystallizes with molecules of 3-exo-chloro-8-oxabicyclo[3.2.1]oct-6-ene-2,4diol (A) and chloroform in a 3:1 ratio, in the space group R3m. Molecules of A straddle a crystallographic mirror plane, whereas the chloroform molecules (C and H atoms) lie additionally on the threefold axis. The molecules of A are linked into right-and left-helical chains by means of O-HÁ Á ÁO hydrogen bonds, thus forming columns running along the c axis. Six interpenetrated columns form a channel in which the solvent molecules (chloroform) are located.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2178).

Comment
It is known (Piettre et al., (1997);Miller & Allemann, (2007)) that the analogous of inositetriphosphates are potential prospective antitumoral compounds. As we assume that the polyhydroxycycloheptanes are able to act like inositemonophosphatase inhibitors, so the 3-exo-chloro-8-oxa-bicyclo[3.2.1]oct-6-en-2,4-diendo-diol was synthesized. The elemental analysis of the compound we obtained, were in good agreement with the title compound, but 1 H NMR data did not allow us to clarify the relative oxy-groups arrangement in the molecule. To determine the structure of the compound, we carried out an X-ray crystallographic analysis. Molecule of (A) (Fig.1) straddle a crystallographic mirror plane m passing through atoms Cl1, C1, H1, endocyclic oxygen O2, the midpoint of the double bond C4/C4 ii , whereas the chloroform molecules (carbon C5 and hydrogen H5 atoms) lie additionally on the threefold axis. The 6-membered cycle of the molecule adopts a chair conformation, with atoms O2 and C1 displaced out of plane defined by the atoms C2/C2 ii /C3/C3 ii (plane 1) by -0.848 (3) and 0.543 (2) Å. Atoms O1, C4, Cl1, H1 (attached to C1) displaced out of plane 1 by 0.797 (2) Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. Symmetry codes: (ii) x, x-y, z; (iii) -y + 1, x-y, z; (iv) 1 -x + y, -x + 1, z.

Special details
Experimental. As the solvent molecules release from the crystal at ambient air, so the experiment was carried out from the crystal placed in a glass capillary.
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 > σ(F 2 ) is used only for calculating Rfactors(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.