4-Cyclopropyl-1-(6′-deoxy-1′,2′-O-isopropylidene-α-d-glucofuranosyl)-1H-1,2,3-triazole

In the title compound, C14H21N3O5, the tetrahydrofuran ring adopts an envelope conformation with the C atom bearing the substituent as the flap. The pentafuranose ring adopts a twisted conformation about the C—C bond fusing the rings. The dihedral angle between these rings (all atoms), which are cis fused, is 72.89 (14)°. The cyclopropane ring is disordered over two orientations in a 0.576 (5):0.424 (5) ratio; the dihedral angles subtended to the triazole ring are 53.3 (11) and 46.6 (9)°, respectively. In the crystal, the molecules are linked by O—H⋯N and O—H⋯O hydrogen bonds, generating (001) sheets. A weak C—H⋯O interaction also occurs.

The tetrahydrofuran ring fuses with one methylenedioxy ring,having the cis arrangement at the ring junctions and giving a V-shaped molecule.
The crystal packing, which features O-H···N hydrogen bonds (Table 1), is shown in Figure 2.

Refinement
All H atoms were placed geometrically and treated as riding on their parent atoms with C-H are 0.96 Å (methylene) or 0.93 Å (aromatic), 0.82 Å (hydroxyl)and U iso (H) =1.2U eq (C).
Attempts to confirm the absolute structure by refinement of the Flack parameter in the presence of 1156 sets of Friedel equivalents led to an inconclusive value of 0.0 (3). Therefore, the absolute configuration was assigned to correspond with that of the known chiral centres in a precursor molecule, which remained unchanged during the synthesis of the title compound.

Figure 1
The molecular structure of (I) showing 30% probability displacement ellipsoids.  Packing diagram for (I).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.