(3,4-Dihydroxyoxolan-2-yl)methyl 4-methylbenzenesulfonate

The racemic title compound, C12H16O6S, possesses a five-membered ring that adopts an envelope-shaped conformation; the two hydroxy groups occupy quasi-axial positions. Adjacent molecules are linked by O—H⋯O hydrogen bonds to generate a ribbon that runs along the a axis of the orthorhombic unit cell. The crystal studied was an inversion twin.

The racemic title compound, C 12 H 16 O 6 S, possesses a fivemembered ring that adopts an envelope-shaped conformation; the two hydroxy groups occupy quasi-axial positions. Adjacent molecules are linked by O-HÁ Á ÁO hydrogen bonds to generate a ribbon that runs along the a axis of the orthorhombic unit cell. The crystal studied was an inversion twin.

Related literature
For the synthesis of the title compound, see: Kapitan & Grazca (2008); Park et al. (2005). For the use of xylitol tosylates in the synthesis of bicyclic oxetanes, see: Kö ll & Oetling (1987

Comment
The title compound is the product of the cyclization of xylitol in the presence of p-toluenesulfonyl chloride. The synthetic procedure is described below. We report here the single-crystal X-ray structure.
Asymmetric unit of the title compound is composed of molecule 1 (Fig. 1). Molecules are linked together into infinite chains by the intermolecular O2-H2···O1 i (Fig. 2) that form dimers by the O3-H3···O3 ii hydrogen bonds. These dimeric chains propagate along the a axis (Fig. 3).

Experimental
In our attempt to make 2,3,4-trihydroxypentane-1,5-diyl bis(4-methylbenzenesulfonate) we have obtained (3,4-dihydroxytetrahydrofuran-2-yl)methyl 4-methylbenzenesulfonate as a major product. The title compound has been synthesized by modification of procedures described by Park et al. (2005) and Kapitan & Grazca (2008). To a solution of racemic Xylitol (33 mmol) in pyridine (40 ml), p-toluenesulfonylchloride (69 mmol) in pyridine was added drop wise at -10°C. The reaction mixture was kept at 4°C overnight, resulting in formation of white precipitate which was removed by filtration. The filtrate was poured over 300 ml of water and kept in an ice bath for 20 minutes. Extraction with dichloromethane, followed by washing of the organic layer with saturated NaCl solution, drying over sodium sulfate, filtration and evaporation yielded the title compound which was finally purified by flash chromatography. In a sample vial, 20 mg of compound was taken and dissolved in MeOH. Upon slow evaporation at 273 K the crystals are formed as colorless blocks.

Refinement
H atoms were positioned geometrically and refined using a riding model with C-H = 0.95-1.00 Å and O-H = 0.84 Å with U iso (H) = 1.2U eq . The Flack parameter refined to nearly 0.5, in agreement with the racemic nature of the Xylitol reactant. Fig. 1. The molecular structure of title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms. (3,4-Dihydroxyoxolan-2-yl)methyl 4-methylbenzenesulfonate

Special details
Geometry. All e.s. 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.