2-(4-Methoxyphenyl)-1,3-thiazolo[4,5-b]pyridine was obtained in 64% yield from reaction of 4-anisic acid and 3-(diisopropylaminothiocarbonylthio)-2-aminopyridine in phosphorus oxychloride under reflux for 4 h [1] or in 82% yield from treatment of 3-(diisopropylaminothiocarbonylthio)-2-(4-methoybenzoylamino)pyridine with hydrochloric acid under reflux for 5 h [2]. Colourless crystals of the title compound were obtained via crystallization from diethyl ether.

The crystal was twinned and refinement was performed using the option HKLF 5 in SHELX [5]. H atoms were placed in calculated positions and refined using a riding model, with U_iso(H) set to 1.2U_eq(C) and aromatic C—H distance of 0.93 Å. The methyl (C—H = 0.96 Å) groups were allowed to rotate around the C—C bond (HFIX 137 option in SHELX [5]) with U_iso(H) set to 1.5U_eq(C).

Various thiazolopyridines have been synthesised via various synthetic methods and many derivatives have shown interesting biological applications [3, 4]. The asymmetric unit of the crystal structure of the title compound consists of two independent molecules of C₁₃H₁₀N₂OS. The methoxyphenyl groups in both molecules are planar, as illustrated by C_Me-O-C_Ph-C_Phtorsion angles of 3.8(5)° and 3.4(6)°. The dihedral angles between the planes through the methoxyphenyl and thiazolopyridine groups of the two molecules are 9.6(2)° and 10.0(1)°, indicating that both molecules are nearly planar. In the crystal, π−π interaction occurs between inversion-related molecules separated by a distance of 3.4 Å of the corresponding planes.

The authors extend their appreciation to the College of Applied Medical Sciences Research Center and the Deanship of Scientific Research at King Saud University for their funding of this research.