Crystal structures of two triazola-dioxola-benzenacyclononaphanes

Two dioxala-benzenacyclononaphanes differ principally by the presence of a pyrrolizine ring system in one and a pyrrolothiazole ring system in the other. In the crystal of the former, molecules are linked via C—H⋯N and C—H⋯O hydrogen bonds, forming sheets parallel to (10) while in the latter, molecules are linked via C—H⋯N, C—H⋯O and C—H⋯S hydrogen bonds, forming slabs parallel to (001).


Chemical context
Triazoles and their derivatives are of great importance in medicinal chemistry and can be used for the synthesis of many heterocyclic compounds with different biological activities such as antiviral, antibacterial, antifungal (Mange et al., 2013), anticancer (Singhal et al., 2011), antituberculosis, anticonvulsant, antidepressant (Sahin et al., 2012) and antiinflammatory activities. They have been reported to be inhibitors of glycogen synthase kinase-3, antagonists of GABA receptors, agonists of muscarine receptors and have been shown to possess anti-HIV-1, cytotoxic, antihistaminic and antiproliferative activities (Pokhodylo et al., 2013). Triazoles are stable to acid and basic hydrolysis and reductive and oxidative conditions because of their high aromatic stabilization. In addition, this heterocycle has a high dipole moment and might participate in hydrogen-bond formation as well as in dipole-dipole and -stacking interactions (Pertino et al., 2013).
In compound (II), the pyrrolidine (D) and thiazole rings (E = N1/C8/S9/C10/C11) have twist conformations on bond N1-C11. The furan and dioxolane rings (B and C) adopt envelope conformations with maximum deviations from the mean planes of 0.631 (3) Å for atom C14 and 0.319 (4) Å for C16. The mean planes of rings B and C are inclined to one another by 68.5 (2) and the mean planes of rings D and E are inclined to one another by 70.8 (2) . This latter dihedral angle is much larger than that in compound (I), cf. 52.8 (3) .

Figure 2
The molecular structure of compound (II), showing the atom labelling. Displacement ellipsoids are drawn at the 30% probability level. H atoms are omitted for clarity.

Supramolecular features
In the crystal of (I), molecules are linked via C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, forming sheets parallel to (101); Table 1 and Fig. 3. In the crystal of (II), molecules are linked via C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, forming helical chains propagating along [010], which are linked via C-HÁ Á ÁS hydrogen bonds, forming slabs parallel to (001); Table 2   The crystal packing of compound (I), viewed approximately normal to plane (101). H atoms not involved in hydrogen bonding (dashed lines; Table 1) have been excluded for clarity.

Figure 4
A view along the c axis of the crystal packing of compound (II), showing the hydrogen-bonded helical chains along [010], linked by C-HÁ Á ÁS hydrogen bonds forming slabs parallel to the ab plane. H atoms not involved in hydrogen bonding (dashed lines; Table 2) have been excluded for clarity. ,3]dioxol-6-yl}oxy)methyl]-1H-1,2,3-triazol-1-yl}ethoxy)benzaldehyde (1 mmol) and proline (1.5 mmol) was refluxed in dry acetonitrile (50 ml) under a nitrogen atmosphere for 9 h. After completion of the reaction, as indicated by TLC, the acetonitrile was evaporated under reduced pressure. The crude product was purified by column chromatography using hexane/EtOAc (3:7) as eluent (yield 75%). After purification the compound was recrystallized in CHCl 3 by slow evaporation yielding colourless block-like crystals.

pyrrolizina-6(4,1)-triazola-3(5,6)-furo[2,3-d][1,3]dioxola-1(1,2)-benzenacyclononaphane
Crystal data  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.

c]thiazola-6(4,1)-triazola-3(5,6)-furo[2,3-d][1,3]dioxola-1(1,2)-benzenacyclononaphane
Crystal data 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.