Facile Novel Synthesis and Reactions of Thiazolidin-4-one Derivatives for Antimicrobial Agents

Antioxidant properties of some novel derivatives thiazolo[4,5-b] pyridine

The synthesis and determination of the antioxidant activity of some novel (5,7-dimethyl-2-oxo-thiazolo[4,5-b]pyridine-3-yl)-acetic acid hydrazide derivatives are described in this article. The transformation of the base heterocycle was carried out via the reactions of acylation, [2+3]cyclocondensation, Knoevenagel condencation and alkylation for the purpose to obtain substances with a satisfactory pharmacological profile. Antioxidant activity of the synthesized compounds was evaluatedin vitroby means of the scavenging metod effect on 2,2 diphenyl-1-picrylhydrazyl (DPPH) radicals.

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5-Ene-4-thiazolidinones - An efficient tool in medicinal chemistry

The presented review is an attempt to summarize a huge volume of data on 5-ene-4-thiazolidinones being a widely studied class of small molecules used in modern organic and medicinal chemistry. The manuscript covers approaches to the synthesis of 5-ene-4-thiazolidinone derivatives: modification of the C5 position of the basic core; synthesis of the target compounds in the one-pot or multistage reactions or transformation of other related heterocycles. The most prominent pharmacological profiles of 5-ene derivatives of different 4-thiazolidinone subtypes belonging to hit-, lead-compounds, drug-candidates and drugs as well as the most studied targets have been discussed. Currently target compounds (especially 5-en-rhodanines) are assigned as frequent hitters or pan-assay interference compounds (PAINS) within high-throughput screening campaigns. Nevertheless, the crucial impact of the presence/nature of C5 substituent (namely 5-ene) on the pharmacological effects of 5-ene-4-thiazolidinones was confirmed by the numerous listed findings from the original articles. The main directions for active 5-ene-4-thiazolidinones optimization have been shown: i) complication of the fragment in the C5 position; ii) introduction of the substituents in the N3 position (especially fragments with carboxylic group or its derivatives); iii) annealing in complex heterocyclic systems; iv) combination with other pharmacologically attractive fragments within hybrid pharmacophore approach. Moreover, the utilization of 5-ene-4-thiazolidinones in the synthesis of complex compounds with potent pharmacological application is described. The chemical transformations cover mainly the reactions which involve the exocyclic double bond in C5 position of the main core and correspond to the abovementioned direction of the 5-ene-4-thiazolidinone modification.

Crystal structure of ethyl 2-acetyl-3,7-dimethyl-5-(thiophen-2-yl)-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate

In the title compound, C₁₇H₁₈N₂O₃S₂, the pyrimidine ring adopts a shallow sofa conformation, with the C atom bearing the axially-oriented thio­phene ring as the flap [deviation = 0.439 (3) Å]. The plane of the thio­phene ring lies almost normal to the pyrimidine ring, making a dihedral angle of 79.36 (19)°. In the crystal, pairs of very weak C—H⋯O hydrogen bonds link the mol­ecules related by twofold rotation axes, forming R₂²(18) rings, which are in turn linked by another C—H⋯O inter­action, forming chains of rings along [010]. In addition, weak C—H⋯π(thio­phene) inter­actions link the chains into layers parallel to [001] and π–π inter­actions with a centroid–centroid distance of 3.772 (10) Å connect these layers into a three-dimensional network.

Crystal structure of ethyl 2-cyano-3-[(1-eth-oxy-ethyl-idene)amino]-5-(3-meth-oxy-phen-yl)-7-methyl-5H-1,3-thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate

In the title compound, C22H24N4O4S, the central pyrimidine ring adopts a sofa conformation with the ring-junction N atom displaced by 0.2358 (6) Å from the mean plane of the remaining ring atoms. The 3-meth-oxy-phenyl ring, at the chiral C atom opposite the other N atom, is positioned axially and is inclined to the thia-zolo-pyrimidine ring with a dihedral angle of 83.88 (7)°. The thia-zole ring is essentially planar (r.m.s. deviation = 0.0034 Å). In the crystal, pairs of weak C-H⋯O hydrogen bonds link mol-ecules related by twofold rotation axes to form R 2 (2)(8) rings, which in turn are linked by weak C-H⋯N inter-actions, forming ribbons along [-110]. In addition, π-π stacking inter-actions [centroid-centroid distance = 3.5744 (15) Å] connect the ribbons, forming slabs lying parallel to (001).