2-Chloromethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine

In the molecule of the title compound, C7H7ClO2S, the six-membered ring adopts a twisted conformation. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules. There is also a weak C—H⋯π interaction.

In the molecule of the title compound, C 7 H 7 ClO 2 S, the sixmembered ring adopts a twisted conformation. In the crystal structure, weak intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules. There is also a weak C-HÁ Á Á interaction.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2630).  In the molecule of the title compound ( Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.  (Cremer & Pople, 1975).

Structure Reports Online
In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. There is also a weak C-H···π interaction (Table 1).

Experimental
For the preparation of the title compound, 3,4-dimethoxythiophene (1.14 g, 7.9 mmol), 3-chloro-1,2-propanediol (2.45 g, 22.2 mmol), p-toluene-sulfonic acid monohydrate (0.151 g, 0.81 mmol) and dry toluene (27 ml) were added into a three necked flask equipped with an argon purge. The mixture was refluxed for 12 h. Then, diol (2.45 g, 22.2 mmol) was added and refluxed for 3 h. It was allowed to cool to room temperature. After removal of the solvent, the remaining crude product was isolated by flash chromatography [silica gel, hexane/dichloromethane (8:2)] to isolate the title compound, as a colorless solid (yield; 58%) (Jose et al., 2005). Crystals suitable for X-ray analysis were obtained by dissolving the title compound (0.1 g) in hexane (25 ml) and evaporating the solvent slowly at room temperature for about 3 d.

Refinement
H atoms were positioned geometrically, with C-H = 0.93, 0.98 and 0.97 Å for aromatic, methine and methylene H, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. 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.