5-Hydroxy-7-methyl-3H-thiazolo [4,5-b]pyridin-2-one was obtained by the reaction of 4-iminothiazolidin-2-one with acetoacetic ester. Further structural modifications include the introduction of diversity at the C 5 and C 6 positions. The anti-inflammatory action of novel thiazolo[4,5-b]pyridine-2-one derivatives was evaluated in vivo employing the carrageenan-induced rat paw edema method. The antioxidant activity of the synthesized compounds was evaluated in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.
The spectrophotometric behavior of a new, first-time synthesized reagent -4-[N'-(4-imino-2-oxo-thiazolidin-5-ylidene)-hydrazino]-benzenesulfonic acid (ITHBA), has been investigated. A simple, rapid, accurate, selective and sensitive method for the spectrophotometric determination of Pd(II) ions using this reagent was developed. The optimal conditions for the formation of the complexes were found. The molar absorptivity at λ = 438 nm is 7.5 × 10 3 L mol -1 cm -1 , and Beer's law is observed for the concentrations ranging from 0.2-2.2 μg mL -1 Pd(II). The effects of extraneous ions were investigated. The method proved to be successful in determination of palladium in the intermetallides and resistor. The accuracy of spectrophotometric palladium assay in real objects with 4-[N'-(4-imino-2-oxo-thiazolidin-5-ylidene)-hydrazino]-benzenesulfonic acid has been confirmed by voltammetric or atomic absorption spectroscopy method.
The interaction of Ru(IV) ions with a novel analytical reagent-5-hydroxyimino-4-imino-1,3-thiazolidin-2-one, by spectrophotometric method was investigated. The complex is formed at pH 5.0 in acetate buffer medium after heating in the boiling water bath (~371 K) for 25 min. The complex has maximum absorption at 350 nm and is stable for 24 h. Beer's law is valid over the concentration range of 0.5-6.1 µg mL-1 for Ru(IV). The molar absorptivity at λ = 350 nm is 6.21 × 10 3 L mol-1 cm-1. The limit of detection of this method is 0.2 µg mL-1. The interfering effect of various cations and anions on the spectrophotometric determination of the Ru(IV) were investigated. The proposed method was successfully applied to the determination of Ru(IV) in alloys.
The antioxidant activity of novel N 3 and C 6 substituted 5,7-dimethyl-3H-thiazolo [4,5-b]pyridine-2one derivatives was evaluated in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The correlation analysis between the antioxidant activity and different subsets molecular descriptors was carried out for 19 compounds. The regression models derived with QSAR-analysis display the significant influence of topological structure, atom and bond type counts, physicochemical properties, and quantum-chemical structure parameters on the free radical scavenging effect of the compounds.
Aim. To synthesize a series of novel 3H-thiazolo[4,5-b]pyridine-2-ones by structural modification of the core heterocycle in its N3- and N6-positions and to evaluate their anticancer activity in vitro on several tumor cell lines. Methods. Organic synthesis, 1H-NMR spectroscopy, trypan blue cell viability assay. Results. A new convenient synthetic approach was developed and optimized conditions were studied for the reaction of preparation of 3H- thiazolo[4,5-b]pyridin-2-one derivatives. 5,7-Dimethyl-3H-thiazolo[4,5-b]pyridin-2-one and 6-phenylazo-5,7- dimethyl-3H-thiazolo[4,5-b]pyridin-2-one were obtained by [3 + 3]cyclocondensation of 4-iminothiazolidone- 2 with acetylacetone and phenylazoacetylacetone in methanol medium in the presence of sodium methylate. They were used as starting compounds for further structural modification of the core thiazolo[4,5-b]pyridine heterocycle in its 3- and 6-positions. On the basis of in vitro cytotoxicity studies of synthesized compounds several structure-functional relationships underlying anticancer potential of 5,7-dimethyl-3H-thiazolo[4,5-b]pyridin- 2-one derivatives were identified. Conclusions. 3H-thiazolo[4,5-b]pyridin-2-one can be considered as a promising molecular scaffold for rational design of potential anticancer drug candidates. Introduction of phenylazo substitute at C6-position of 3H-thiazolo[4,5-b]pyridin-2-one proved to be the most efficient, as it led to 3-fold increase of its anticancer potential
Novel N3 substituted derivatives of 4-iminothiazolidine-2-one were synthesised under the reactions of [2+3]cyclocondensation, thionation and aminolysis. The functionalisation of 3-phenyl-4-imino-thiazolydine-2-one was carried out in its C5 position under condensation Knoevenagel and nitrosation reactions. The antioxidant activity of the synthesised compounds was evaluated in vitro by the method of their scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. When compared with existing antioxidants, some of our compounds were found to be more potent.
By the reaction of acetylacetone and arylazoacetylacetones with 4-iminothiazolidin-2-one thiazolo [4,5-b]pyridines were obtained in good yields. Optimum reaction conditions were chosen and some properties of compounds obtained were studied.Five-membered heterocycles fused to the pyridine ring attract constant attention since many compounds of this class possess the biologic action. Thiazolo [4,5-b]pyridines are among the least accessible and in turn poorly understood representatives of this class of organic substances. The information on their biological activity is also insuffi cient. In particular, among this type compounds substances were found possessing fungicidal action [1], antagonists of Н3-histamine receptors [2], antagonists of metabotropic glutamate receptors 5 (mGluR5) [3] of high inhibitor activity with respect to the receptors of the epidermal growth factor [4] and a number of other enzymes [5,6].Two fundamentally different approaches exist with respect to the synthesis of the thiazolo[4,5-b]pyridine system. The fi rst one is based on the fusion of the thiazole ring to the pyridine. Here 2-aminopyridines [7], thioureas[8-10], or thiocarbamates [11] are used as initial compounds. The second procedure of the pyridine ring fusion is underlain by a three-component condensation of derivatives of 4-aminothiazoles and 4-aminoselenazoles with aromatic or aliphatic aldehydes and the Meldrum's acid [12]. At the use in the reaction with 2,4-diaminothiazoles of ethyl acetoacetate and acetylacetone 2-amino-5,7-dimethylthiazolo[4,5-b]pyridines and 2-amino-7-methyl-4Н-thiazolo[4,5-b]pyridin-5-ones were obtained respectively [13]. Examples are also known of the synthesis of 1,3-thiazolo[4,5-b]pyridine derivatives with the use of solid-phase carriers [14] and with the application of dominoreactions [15].We report here on a convenient method of preparation of 3H-thiazolo[4,5-b]pyridin-2-one derivatives. We used 4-iminothiazolidin-2-one (I) as the initial compound [16] that was reacted with acetylacetone (II). We optimized the conditions of this reaction that made it possible to obtain 5,7-dimethyl-3H-thiazolo[4,5-b]-pyridin-2-one (IV) in good yield. The best results were observed at keeping the reagents mixture in methanol in the presence of sodium methylate over 5 days. Similar procedure was described earlier in patent [17], but due to the low yield the method had no preparative value.We also studied the behavior in this reaction of acetylacetone arylazo derivatives IIIа-IIIg (Scheme 1). Under the chosen conditions the corresponding 6-arylazo-5,7-dimethyl-3H-thiazolo[4,5-b]pyridin-2-ones Vа-Vg formed in good yields. These substances were orange or red crystalline powders well soluble in DMF and DMSO, sparingly soluble in water and the other organic solvents.The structure of compounds obtained was proved by NMR spectra. For instance, the proton signals of the methyl groups of the pyridine ring are observed at 2.42-2.46 and 2.49-2.87 ppm respectively, and of NH groups, in a relatively wide range of 9.78-14.29 ppm.Some...
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