Ethyl 1-[(2-chloro-1,3-thiazol-5-yl)methyl]-5-methyl-1H-1,2,3-triazole-4-carboxylate

In the title compound, C10H11ClN4O2S, the triazole ring carries methyl and ethoxycarbonyl groups and is bound via a methylene bridge to a chlorothiazole unit. There is also evidence for significant electron delocalization in the triazolyl system. Intra- and intermolecular C—H⋯O hydrogen bonds together with strong π–π stacking interactions [centroid–centroid distance 3.620 (1) Å] stabilize the structure.

In the title compound, C 10 H 11 ClN 4 O 2 S, the triazole ring carries methyl and ethoxycarbonyl groups and is bound via a methylene bridge to a chlorothiazole unit. There is also evidence for significant electron delocalization in the triazolyl system. Intra-and intermolecular C-HÁ Á ÁO hydrogen bonds together with strongstacking interactions [centroidcentroid distance 3.620 (1) Å ] stabilize the structure.
We report here the crystal structure of the title compound, (I) (Fig. 1), which was synthesized by introducing pyridine rings into a 1,2,3-triazole molecular framework.
In the title compound, the C5-N2 and C6-N4 bonds are significantly shorter than that of the single bond of C-N (1.47 Å; Sasada, 1984) and close to the value of the double bond of C-N (1.28 Å; Wang et al., 1998). This indicates significant electron delocalization in the triazolyl system.

Experimental
Ethyl acetylacetate (2 mmol) and 5-azidomethyl-2-chlorothiazole (2 mmol) were added to a suspension of milled potassium carbonate (2 mmol) in DMSO (10 ml). The mixture was stirred at room temperature for 6 h (monitored by thin-layer chromatography) and poured to water (50 ml). The solid was collected by filtration, washed with water and diethyl ether, respectively, and dried to give 0.52 g of the title compound (yield 91%). Colourless crystals of (I) suitable for X-ray structure analysis were grown from acetone and petroleum ether (1:1, v/v).

Refinement
H atoms bonded to C were placed at calculated positions, with C-H distances in the range 0.93 -0.98Å. They were refined using a riding model, with U iso (H) = 1.2U eq (C), or 1.5U eq (methyl C). Fig. 1. View of the molecular structure of (I), showing the atom labelling scheme and with displacement ellipsoids drawn at the 50% probability level.