1,2,3,4,5,6-Hexa-O-acetyl-scyllo-inositol

The title molecule, C18H24O12, has crystallographic 2/m symmetry with two acetate group located on a mirror plane. The H—Csp 3—O—Csp 2 torsion angles characterizing orientation of the acetyl groups with respect to the cyclohexane ring are 0.0, 23.9 and −23.9°. The cyclohexane ring is in a chair conformation with all substituents in equatorial positions. In the crystal, molecules are connected through C—H⋯O hydrogen bonds into a chain extending along the c axis.

The title molecule, C 18 H 24 O 12 , has crystallographic 2/m symmetry with two acetate group located on a mirror plane. The H-Csp 3 -O-Csp 2 torsion angles characterizing orientation of the acetyl groups with respect to the cyclohexane ring are 0.0, 23.9 and À23.9 . The cyclohexane ring is in a chair conformation with all substituents in equatorial positions. In the crystal, molecules are connected through C-HÁ Á ÁO hydrogen bonds into a chain extending along the c axis.

Experimental
In the title compound ( Fig. 1), all bond lengths and angles are normal and correspond to those observed in related structure (Abboud et al., 1990). The twist angles characterizing orientation of the acetyl group with respect to the cyclohexane ring are: H1-C1-O2-C3 = -23.9°, H2-C2-O1-C5 = 0.0°. The cyclohexyl ring is in the chair conformation. Intermolecular C-H···O hydrogen bonds (Table 1) link the molecules into chains along the c axis..

Experimental
Dried roots (2 kg) of P. hysterophorus was crushed, water extract was prepared and lyophilized. Dry powder (5 g) obtained was treated with pyridine (50 ml) and acetic anhydride (60 ml) and was stirred at room temperature. Progress of the reaction was checked by TLC. After completion of the reaction, mixture was treated dropwise with 1.5 N aqueous HCl (50 ml) and then extracted with ethyl acetate (3x100mL). After usual workup and removal of the solvents the reaction product obtained was 8 g. Chromatographic separation of the products on a silica gel column using chloroform: methanol (99:1 to 80:20) as eluent, gave pure myo-inositol hexaacetate and later fractions gave scyllo-inositol hexaacetate as white crystals m.p. 651-653 K. Single crystal of the compound was grown by slow evaporation technique using methanol /chloroform as the solvent system.

Refinement
All H atoms (except methyl C6 H) were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.96-0.98 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C).   The packing arrangement of molecules viewed down the a axis. For clarity, hydrogen atoms which are not involved in hydrogen bonding have been omitted. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (