Ethyl 5-amino-3-methylsulfanyl-1H-pyrazole-4-carboxylate

In the title compound, C7H11N3O2S, bond lengths and angles are within normal ranges. The crystal packing is stabilized by intermolecular N—H⋯O hydrogen bonds, linking the molecules into infinite one-dimensional chains along the a axis.

In the title compound, C 7 H 11 N 3 O 2 S, bond lengths and angles are within normal ranges. The crystal packing is stabilized by intermolecular N-HÁ Á ÁO hydrogen bonds, linking the molecules into infinite one-dimensional chains along the a axis.

Related literature
For the biological activity, see: Hanefeld et al. (1996). For a similar structure, see: Ren et al. (2004).

Experimental
Crystal data
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2437).

Comment
The title compound, is an important intermediate in synthesis of heterocyclic compounds (Hanfeld et al., 1996) in particular, in producing imidazo[1,2-b]pyrazole derivatives. Here, we report the crystal structure of (I).
In compound (I), all bond lengths and angles are normal and in a good agreement with those reported previously (Ren et al., 2004). The pyrazole ring C4/C5/C5/N2/N3 and bonded atoms N1, S1, C3, O1, C2 and C1 are coplanar, the largest deviation from the mean plane being 0.053 (2)Å for atom C3. The crystal packing is stabilized by intermolecular N-H···O hydrogen bonds, linking the molecules into infinite one-dimensional chain along the a axis.

Experimental
A round-bottomed flask fitted with a dropping funnel was charged with 11.2 g (0.2 mol) potassium hydroxide in 200 ml MeCN. The solution was cooled in an ice bath. Through the dropping funnel 22.7 g (0.2 mol) ethyl cyanoacetate was added gradually. After stirring at 273K for 0.5 h, 15.2 g(0.2 mol) carbon bisulfide was added while vigorous stirring. Keep stirring for 1 h, 50.4 g(0.4 mol) dimethyl sulfate was added through the drop funnel, then left overnight. The reaction mixture was filtered and filtrate evaporated on a rotary evaporator to remove the solvent. The mixture was dissolved in 50 ml ethanol, then through a drop funnel 12.5 g (0.2 mol) of hydrazine hydrate was added. The solution was evaporated in vacuo to afford crude product, which was purified by column chromatography to give the desired product 34.7 g, yield 86.3%. Crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of a methanol solution at room temperature for one week.

Refinement
All H atoms were placed in calculated positions, with C-H = 0.93 or 0.97 Å, N-H = 0.86 Å, and included in the final cycles of refinement using a riding model, with U iso (H) = 1.2 (1.5 times for methyl) times U eq (C,N). Fig. 1. View of the title compound (I), with displacement ellipsoids drawn at the 40% probability level.

Figures
Ethyl 5-amino-3-methylsulfanyl-1H-pyrazole-4-carboxylate as those based on F, and R-factors based on ALL data will be even larger.