No abstract
A series of new derivatives of 1,2,4-triazoles have been synthesized and their antioxidant properties have been studied. It was established that the obtained compounds exhibit a stabilizing effect on cell membranes and demonstrate antioxidant activity with respect to erythrocytes under oxidative stress conditions.
A method has been developed for the synthesis of new heterocyclic compounds containing g-butanolide fragments. The antibacterial properties of the obtained compounds have been investigated. The tested compounds exhibit moderate antibacterial activity.Ketolactones are known to be good synthons for preparing heterocyclic compounds of various classes. In particular, thiazolyl-and triazolyl-derivatives of lactones [1, 2], indolyllactones with cardiovascular properties [3,4], and thiosemicarbazones of ketolactones with antimutagenic activity [5] have been synthesized from them. Furthermore, the last can be used as starting materials for synthesizing a new class of lactone-containing heterocyclic compounds. We prepared thiosemicarbazones of ketolactones with various structures by reacting the latter with thiosemicarbazide in aqueous alcohol.The optimum conditions for obtaining high yields of IIa -j were developed. Next, we studied the reaction of thiosemicarbazones IIa -j with substituted bromoacetophenones. It was found that substitution and further heterocyclization formed a new class of lactone-containing heterocyclic compounds, hydrobromides of 2,4,4-trisubstituted 2-[2¢-(3¢-arylthiazol-2¢-yl)hydrazono]propyl(butyl)butanolides (IIIa -p), treatment of which with aqueous ammonia gave the corresponding free bases (IVa -p).The optimum conditions were developed to give high yields (78 -93%) of the target products.All synthesized compounds were characterized by physicochemical constants and IR and PMR spectra. The purity was verified by TLC and elemental analyses, which agreed with those calculated for each product. 144 0091-150X/09/4303-0144
New 1,2,4-triazole-3-thiols were synthesized by reactions of the corresponding carboxylic acid hydrazides with isothiocyanates and subsequent cyclization of intermediate 1,4-substituted thiosemicarbazides. Alkylation of 1,2,4-triazole-3-thiols with benzyl chlorides and bromacetophenones gave only S-substituted derivatives. † Deceased.Biological studies on synthetic analogs of naturally occurring heterocyclic compounds showed that most of them exhibit a broad spectrum of biological activity. Among compounds of this series, of particular interest are 1,2,4-triazoles which are mostly of synthetic origin. Some 1,2,4-triazole derivatives exhibit hypotensive effect [1] and possess antitumor [2], fungicidal [3], antibacterial [4], and other kinds of biological activity.While searching for new useful properties in the series of 1,2,4-triazoles we synthesized their new derivatives. Reactions of carboxylic acid hydrazides Ia-Id with allyl, phenyl, and furfurylmethyl isothiocyanates gave 1,4-disubstituted thiosemicarbazides IIa-IIe. Optimal conditions for this reaction were found. The best results were obtained by heating the initial reactants in ethanol for a short time [5]. Compounds IIa-IIe underwent intramolecular cyclization in alkaline medium to form targeted 3,4-disubstituted 1,2,4-triazole-3-thiols IIIa-IIIe. It is advisable to carry out this reaction with the use of 10% aqueous sodium or potassium hydroxide. The cyclization was complete in 4 h, and compounds IIIa-IIIe were formed in high yield [6] (Scheme 1).From the viewpoint of biological activity, synthesis of 1,2,4-triazole-3-thiol derivatives substituted at the sulfur atom seemed to be promising. For instance, biological effects of compounds possessing free and substituted thiol groups could be compared. 3,4-Disubstituted 1,2,4-triazole-3-thiols IIIa-IIIe were subjected to alkylation with various halogen derivatives, specifically with substituted benzyl chlorides and bromoacetophenones (Scheme 2). The optimal conditions for the alkylation with benzyl chlorides included the use of anhydrous acetone as solvent and anhydrous potassium carbonate as base and prolonged heating (10 h). The reactions of III with bromoacetophenones were complete in 2 h in the absence of a base.
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