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A series of substituted 6-alkyl(6H)-3-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines have been synthesized by reaction of 3-alkyl-4-amino-5-thio-1,2,4-triazoles with substituted phenacylbromides in the presence of an equimolar amount of KOH. Mass spectra for the dissociative ionization by electron impact, antibacterial activity, and antitumor properties of the synthesized compounds have been studied. It was established that some compounds at doses of 50 -100 mg/kg decrease the growth of sarcomas 45 and 37 by 35 -47%.

The physicochemical properties and antitumor activity of dacarbazine, its analogs, and the new alkylating agent imidazene are reviewed. It is shown that the activity of dacarbazine is superior to most of its analogs. Imidazene exhibits an advantage over dacarbazine with respect to both stability and activity and can be used for the treatment of malignant melanoma and sarcoma of soft tissues and in combined chemotherapy.

Interaction of 4-amino-5-(2-alkoxyphenyl)-4H-[1,2,4]triazole-3-thiols with substituted phenacyl bromides was used to synthesize 6-(2¢-alkoxyphenyl)-3-aryl-7H- [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines. Biological studies identified an interaction between chemical structure and antibacterial activity in this series of triazolothiadiazines.Previous studies yielded triazolothiadiazines (TTD) containing alkyl [1] or 4-alkoxyphenyl substituents in position 6 [2] and substituted phenyl radicals in position 3, and the biological properties of TTD were studied. Among them were compounds with activity similar to that of norsulfazol but less active than furazolidone in terms of antibacterial activity [1,2]. Some TTD were also shown to have inhibitory activity on the growth of sarcoma 45 and 37, to extents of 35 -47% [1].We describe here 3,6-diaryl-7H-[1,2,4]triazolo[3,4-b]-[1,3,4]thiadiazines (XV -XL) containing 2-alkoxyphenyl groups in position 6 and substituted phenyl radicals in position 3, prepared by interaction of 4-amino-5-(2-alkoxyphenyl)-4H-[1,2,4]triazole-3-thiols (I -III) with substituted phenacyl bromides (IV -XII) in the presence of an equimolar quantity of potassium hydroxide (method A). TTD prepared by this method, where R 1 = C 2 H 5 or C 3 H 7 , in contrast to the methoxy derivatives (XV -XXII), were obtained at low yield. Along with TTD, the reaction mixes in some cases additionally produced intermediate noncyclized products (XIII, XIV), which were also characterized. The TTD synthesis scheme by method A is shown in Scheme 1.TTD yields were increased when reactions were run using indirect interaction of triazole thiols II, III with phenacyl bromides IV -XII (method B). This approach produced 2-ethoxy-and 2-propoxyphenyl TTD derivatives (XXIII -XL) at relatively high yield.The HBr evolved during the reaction evidently catalyzed intramolecular cyclization, as in the interaction of phenacyl bromides with 2-thio-4,5-dihydroimidazole with formation of 3-phenyl-5,6-dihydroimadazo[2, 1-b]thiazoles [3,4] or phenacyl bromides with thiourea, leading to 4-phenyl-thiazoles [5].Acetyl derivative XXVIII was deacetylated with 17% hydrochloric acid to produce amino derivative XIX.The 1 H NMR spectra of TTD contained signals from the SCH 2 group, benzene ring protons, and amino and alkoxy groups, giving their structures.The mass spectrum of 3-(4-chlorophenyl)-6-(2¢-ethoxyphenyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (XXV) was studied and its overall degradation pathway was identified. It follows from this pathway that dissociative ionization of compound XXV, with some individual features, corresponds to the degradation of the 6-alkyl-and 6-(4-alkoxyphenyl) derivatives described in [1,2]. The mass spectrum contained a peak for the molecular ion with m/z 370/372, two key peaks, A and B, obtained by elimination of 2-ethoxyphe-

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