Benzoxazolyl-and benzothiazolyl-guanidines in three-component reactions

The previously unknown three component condensation of hetarylguanidines, orthoesters, and active methylene carbonyl compounds has been studied. Depending on the nature of the latter products of both linear combination and subsequent cyclizationl leading to pyrimidine or tetrahydroquinazoline structures were obtained. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1080–1088, July, 2006.     

1,3-Dipolar cycloaddition of 2-benzylideneindan-1,3-dione α-oxide to olefins

A carbonyl ylid, which reacts with maleic anhydride, N-phenylmaleinimide, and -nitrostyrene to form adducts resulting from 1,3-dipolar cycloaddition, is formed reversibly when 2-benzylideneindan-1,3-dione -oxide is heated (80C). The reaction proceeds regio- and stereospecifically.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1463–1466, November, 1987.     

Synthesis, structure, and antioxidant activity of hybrid N-substituted salicylic acid amides

Sterically hindered phenols, 3-tert-butyl-N-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-ethyl-2-hydroxybenzamide and N-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propyl]-2-hydroxybenzamide, were synthesized as potential antioxidants, and the formation of hydrogen bonds by their molecules was shown by UV and IR spectroscopy.     

Diphthalolylpyrkolidines from 2-arylidene-1,3-indandiones and phenyl azide

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 269–270, February, 1989.     

Synthesis of polyazaheterocycles containing linearly bound 1,2,4-thiadiazole using enaminones

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.     

Preparation of some substituted 1,2,4-triazines

By nitrosating 6-R-1,2,4-triazine-3,5-diones(thiones) the corresponding 4-nitroso derivatives are obtained. On reacting methyl iodide with 3-thio-4-nitroso-6-R-1, 2,4-triazin-5-ones their methyl analogs are obtained. The influence of structural factors on the course of the reactions has been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 400–402, March, 1986.     

Spiro epoxy ketones. 2. Thermal transformations of 2-benzylideneindan-1,3-dioneα-oxide

2-Phenyl-3,3,4,4-diphthaloyloxetane is formed when solutions of 2-benzylideneindan-1,3-dione -oxide in benzene or carbon tetrachloride are heated, while 5-oxo-3-phenyl-2,2-phthaloyl-2,3-dihydroindeno[2,3-b][1,4]dioxine is formed when solutions in dioxane are heated.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 881–884, July, 1988.     

Transalkylation of phenols over heteropoly acids

Transalkylation of 2,6-di-tert-butyl-4-R-phenols over solid heteropoly acids (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₂O₄₀/SiO₂, H₄SiW₁₂O₄₀/SiO₂) in the presence of toluene or o-xylene as acceptors of a tert-butyl group at 100–140 °C produces 4-R-phenols with 92–98% yield (R = H, alkyl, aryl, etc.). HPAs are effective catalysts for the transalkylation of p-cresol and 2, 6-ditert-butyl-4-methylphenol.

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2,6----4-R- (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₂O₄₀/SiO₂, H₄SiW₁₂O₄₀/SiO₂) 0- - 100–140°C 4-R- 92–98% (R = H, , ..). - 2,6----4-.

     

Interrelation between the Inhibiting Properties and the Activity of Phenoxy Radicals of Antioxidants Different in Structure

Efficiency of the inhibiting action of phenol-based antioxidants (AO) was studied in initiated oxidation of methyl oleate (MO). The following AO were examined: hydroxybenzene (I), tyrosol (4-2-hydroxyethylphenol) (II), 2-tert-butyltyrosol (III), 2,6-di-tert-butyltyrosol (IV), 4-3-hydroxypropylphenol (V), 2,6-di-tert-butylphenol (VI), dibunol (2,6-di-tert-butyl-4-methylphenol) (VII), and -tocopherol (VIII). The rate constants k ₇ determining the activity of AO in the reaction with peroxide radicals were equal to (0.94, 0.97, 0.93, 0.75, 0.92, 1.30, and 360.00) × 10⁴ M^-1 s^-1 for compounds II, III, IV, V, VI, VII, VIII, respectively. For inhibitors II-VI, VIII, the dependence of the induction period on the AO concentration was of an extreme character, and the most efficient concentrations of AO (C _max) were equal to (0.7, 1.0, 1.6, 1.0, 1.1, and 2.5) × 10^-3 M, respectively. The efficiency of inhibitors (_max and C _max) was demonstrated to rise with increasing extent of shielding of the OH group and shortening of the chain of a substituent in the para position. Using the stationary photolysis method, the rate constants of disproportionation (k ₉) of phenoxy radicals of inhibitors I, III, VII, and VIII were evaluated and equal to (0.52, 2.38, 3.40, and 0.94) × 10³ M^-1 s^-1, respectively, at 20°C. It was shown that the k ₉ value depended on the extent of shielding of phenoxy radicals. The rate constants (k _{10, eff}) were determined for the reaction of phenoxy radicals with lipids with various extents of unsaturation: MO, linoleic and arachidonic acids. The values of k _{10, eff} for the reaction of phenoxy radicals of I, III, VII, and VIII with linoleic acid (20°C) were equal to (0.69, 0.48, 0.09, and 0.49) × 10² M^-1 s^-1, respectively. It was found that in MO oxidation, the k _{10, eff} values decreased in proportion to the number of ortho-tert-butyl substituents in an AO molecule. For the reactions of phenoxy radicals of inhibitor VII with MO, linoleic and arachidonic acids, the values of k _{10, eff} increased with the number of double bonds in a substrate and were equal to (0.09 ± 0.01, 0.09 ± 0.01, and 0.64 ± 0.04) × 10² M^-1 s^-1, respectively. The k _{10, eff} rate constants for the reaction of phenoxy radicals of compound VIII with the same lipids were equal to (0.20 ± 0.04, 0.49 ± 0.01, and 0.74 ± 0.12) × 10² M^-1 s^-1, respectively.