(4S,5S)-2-(2-Thienyl)-1,3-dioxolane-4,5-dicarboxamide

In the title compound, C9H10N2O4S, which is an important intermediate for the preparation of antitumor platinum drugs, the dioxolane ring adopts an envelope conformation with the C atom bonded to the thienyl ring at the flap position. Intramolecular N—H⋯O and C—H⋯O hydrogen bonds result in the formation of two five-membered rings having envelope conformations. In the crystal structure, intermolecular N—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

In the title compound, C 9 H 10 N 2 O 4 S, which is an important intermediate for the preparation of antitumor platinum drugs, the dioxolane ring adopts an envelope conformation with the C atom bonded to the thienyl ring at the flap position. Intramolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds result in the formation of two five-membered rings having envelope conformations. In the crystal structure, intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.

Structure Reports Online
In the molecule of the title compound (Fig 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
Ring A (S/C1-C4) is, of course, planar, while ring B (O1/O2/C5-C7) adopts an envelope conformation with C5 atom displaced by 0.529 (3) Å from the plane of the other ring atoms. The intramolecular N-H···O and C-H···O hydrogen bonds (Table 1)  In the crystal structure, intermolecular N-H···O and C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title compound, a mixture of thiophene-2-carbaldehyde (272 mg, 2.43 mmol), (2S,3S)-diethyltartrate (500 mg, 2.43 mmol), anhydrous copper sulfate (776 mg, 2.86 mmol) and methanesulfonic acid (1 drop) in anhydrous toluene (8 ml) was stirred at room temperature for 12 h. Anhydrous potassium carbonate (40 mg) was added, and then stirred for a further 20 min. The resulting colorless precipitate was obtained by evaporation, and dried in the vacuo. This product (10 mmol) was dissolved in anhydrous ethanol (50 ml), then a current of dry ammonia, dried with calcium chloride, was passed over the reaction mixture at room temperature for about 4 h. The reaction mixture was evaporated to dryness.
Crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution after three weeks.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH 2 ) and C-H = 0.93 and 0.98 Å for aromatic and methine H, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C,N).
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Hydrogen bonds are shown as dashed lines.

Data collection
Enraf-Nonius CAD-4 diffractometer R int = 0.015 Radiation source: fine-focus sealed tube θ max = 26.0º Monochromator: graphite θ min = 1.7º T = 294 K h = 0→10 ω/2θ scans k = −5→5 Absorption correction: ψ scan (North et al., 1968)  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.