We present herein the synthesis in good yields of two series of highly functionalized thiazolidinone derivatives from the reactions of various 4-phenyl-3-thio-semicarbazones with ethyl 2-bromoacetate and diethyl acetylenedicarboxylate, respectively.

As part of our project devoted to the synthesis of heterocycles including thiazole rings, some new 5-arylidene-2-thioxo-3-N-arylthiazolidin-4-ones were synthesized by Knoevenagel condensation. An interesting feature of these compounds is that their chirality is induced by that of their 3-N-(2-alkyloxyaryl)-2-thioxothiazolidin-4-one precursors, which in turn is due to the presence of a C2 axis of chirality. These new compounds were characterized by spectroscopic methods (IR, ¹H-NMR, ¹³C-NMR). The structure of compound (Z)-(2g) was further determined by X-ray diffraction.

In the title compound, C₂₄H₁₉N₃O₅S, the thiazole ring (r.m.s. deviation = 0.012 Å) displays a planar geometry and is surrounded by three fragments, two methoxyphenyl and one nitrophenyl. The thiazole ring is almost in the same plane as the nitrophenyl ring, making a dihedral angle of 20.92 (6)°. The two methoxyphenyl groups are perpendicular to the thiazole ring [dihedral angles of 79.29 (6) and 71.31 (7)° and make a dihedral angle of 68.59 (7)°. The molecule exists in anZ,Zconformation with respect to the C=N imine bond. In the crystal, a series of C—H...N, C—H...O and C—H...S hydrogen bonds, augmented by several π–π(ring) interactions, produce a three-dimensional architecture of molecules stacked along theb-axis direction. The experimentally derived structure is compered with that calculated theoretically using DFT(B3YLP) methods.

A new process is described for preparing very pure linear alkanethiols and linear α,ω-alkanedithiols using a sequential alkylation of the title compound, followed by a ring closure to quantitatively give the corresponding 3-methyl[1,3]thiazolo[3,2-a]-[3,1]benzimidazol-9-ium salt and the alkanethiol derivative under mild conditions. The alkanethiol and the heteroaromatic salt are easily separated by a simple extraction process. The intermediate thiazolium quaternary salts resulting from the first reaction step can be isolated in quantitative yields, affording an odourless protected form of the thiols.

In the title compound, C₁₈H₂₀N₄O₃S, the 1,2,4-triazole ring is twisted with respect to the mean plane of quinoline moiety at 65.24 (4)°. In the crystal, molecules are linked by weak C—H...O and C—H...N hydrogen bonds, forming the three-dimensional supramolecular packing. π–π stacking between the quinoline ring systems of neighbouring molecules is also observed, the centroid-to-centroid distance being 3.6169 (6) Å. Hirshfeld surface (HS) analyses were performed.