STRUCTURE OF A DENSELY OXYGENATED CARBOCYCLE .2.

(3aR-{3aalpha,4alpha,5beta[R*(S*)],6alpha,6aalpha})-Methyl alpha-(cyclohexylhydroxymethyl)-4-{[(1,1-dimethylethyl) dimethylsilyl]oxy}tetrahydro-6-hydroxy-2,2-dimethyl-4H-cyclopenta-1,3-dioxole-5-acetate, C24H44O7Si, (I), M(r) = 472.69, orthorhombic, P2(1)2(1)2(1), a = 9.496 (1), b = 12.508 (2), c = 23.317 (4) angstrom, V = 2769.5 (7) angstrom3, Z = 4, D(x) = 1.16 g cm-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 1.2 cm-1, F(000) = 1032, T= 298 K, R = 0.0475 and wR = 0.0579 for 2409 reflections [I greater-than-or-equal-to 3sigma(I)]. Crystal chirality was assigned on the basis of the carbohydrate D-(-)-arabinose which was used to prepare the crystals. Chiral centers C2, C3 and C4 in D-(-)-arabinose are fixed in the densely oxygenated cyclopentane ring at the 1,3-dioxole ring fusion and at the C atom bearing the siloxy functionality. The molecules are involved in two kinds of hydrogen bonding: an intramolecular hydrogen bond exists between O6 and O8-H8' [O8-H8'...O6; O8-H8' = 0.76 (4), H8'...O6 = 2.04 (4), O8...O6 = 2.768 (4) angstrom and O8-H8'...O6 = 161 (5)-degrees]; H6' bonds together two molecules related by a 2(1) screw axis along the a axis [O6-H6'...O8 (x - 0.5, - y + 1.5, - z); O6-H6' = 0.84 (5), H6'...O8 = 2.08 (5), O6...O8 = 2.917 (4) angstrom and O6-H6'...O8 = 175 (4)-degrees]. The latter interaction results in infinite chains of hydrogen-bonded molecules in the a-axis direction.