Dithiobiuretes in reactions with electrophilic acetylenes. New derivatives of 1,3,5-dithiazines,-thiadiazines and-triazines as the products of competing reactions of nucleophilic cycloaddition

The nucleophilic addition of 2,4-dithiobiurete, 1- and 1,4-substituted 2,4-dithiobiuretes (2 a-e) with benzoylacetylene (1) has been studied. 2-(Benzoylmethyl)-4-(R¹-imino)-6-(R²-imino)dihydro-4H-1,3,5-dithiazinium perchlorates (3 a-e) are obtained in glacial acetic acid (AcOH) in the presence of equimolar quantities of HClO₄. The reaction of benzoylacetylene with 1,5-diphenyl-2,4-dithiobiurete in either of MeOH, C₆H₆, or MeCN solvents proceeds non-selectively to give a mixture of products such as 2-(benzoylmethyl)-4,6-di(phenylimino)dihydro-4H-1,3,5-dithiazine (5), 2-(benzoylmethyl)-4-(β-benzoylvinyl)thio-3-phenyl-6-(phenylimino)-3,6-dihydro-2H-1,3,5-thiadiazine (8), 2-(benzoylmethyl)-1,3-diphenylhexahydro-1,3,5-triazine-4,6-dithione (7) and N-(β-benzoylvinyl)-N-phenylthioureas (6).     

Hypepontine,a new quaternary alkaloid with antimicrobial properties

Abstract

New isoquinoline alkaloid hypepontine (1) together with a five known compounds, were identified in Hypecoum ponticum Velen, the partial synonym of Hypecoum procumbens L. The structure of the new substance was elucidated based on spectroscopic evidence. The tertiary and quaternary alkaloid mixtures as well as the isolated alkaloids were evaluated for their antibacterial and antifungal activity. The result revealed that the crude alkaloid mixture containing quaternary isoquinoline alkaloids showed potent antifungal and antibacterial activity.     

Polarography of nitro and carbonyl derivatives of arylfurans in anhydrous dimethylformamide

It is shown that the first reversible one-electron wave in the reduction of 5-arylfurans in anhydrous dimethylformamide (DMF) corresponds to the formation of an anion radical and that the subsequent waves are associated with cleavage of the C-Hal bond in the case of halo derivatives and with reduction of the anion radical and the arylfuran fragment. The character of the reduction of 5-(p-nitrophenyl)furan derivatives is determined by the ability of the substituent in the 2 position to delocalize the negative charge. In conformity with this, the first two reversible waves of carbonyl-substituted derivatives are one-electron waves and correspond to the formation of a stable dianion, the greatest contribution to the resonance hybrid of which is made by a p-quinoid structure. The second wave of 5-(p-nitrophenyl)furan and its 2-CH₂OH derivative is irreversible and corresponds to the transfer of three electrons. Lithium ions have a substantial effect on the height and E_1/2 value of the second reduction wave, and this effect is manifested more markedly, the less the substituent in the 2 position is capable of delocalizing the negative charge. The transmission factor of the furan ring is 0.48.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 165–172, February, 1977.     

1,2,4- and 1,2,5-oxadiazoles

It is shown that the first step in the reduction of the investigated oxadiazoles on a dropping mercury cathode in dimethylformamide corresponds to two-electron cleavage of the N-O bond. The degree of reduction is determined by the nature and position of the substituents in the oxadiazole ring and by the rate of protonation of the intermediately formed particles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 38–40, January, 1979.     

Synthesis of copolymer brushes endowed with adhesion to stainless steel surfaces and antibacterial properties by controlled nitroxide-mediated radical polymerization

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto stainless steel, followed by the nitroxide-mediated radical polymerization of 2-(dimethylamino ethyl)acrylate and styrene or n-butyl acrylate, initiated from the electrografted polyacrylate chains. The grafted copolymers were quaternized in order to endow them with antibacterial properties. Peeling tests have confirmed the strong adhesion of the grafted copolymer onto the stainless steel substrate. Quartz crystal microbalance experiments have proven that fibrinogen adhesion is lower on the hydrophilic quaternized films compared to the nonionic counterpart. Such quaternized copolymers exhibit significant antibacterial activity against the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli.     

Influence of substituted 1,4-anthraquinones on the chlorophyll fluorescence and photochemical activity of pea thylakoid membranes

The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluorescence of thylakoid membranes was examined. Both the fluorescence and the photochemical activity depend on the 1,4-anthraquinone substituent. Stronger quinone-induced quenching of the chlorophyll fluorescence than quinone-induced changes in the activity of photosystem II is observed. The type (Cl or Br) and the position (Cl) of the chalogen atom strongly influence the degree of inhibition of PSII electron transport and the quenching of chlorophyll fluorescence. The data suggest that the quenching of chlorophyll fluorescence is due rather to the interaction of the 1,4-anthraquinones and chlorophyll molecules than to an indirect effect caused by stimulation of the photochemistry.     

A study on modified polymers by means of i.r. spectroscopy and thermal analysis

Curing and destruction of phenol-formaldehyde resins, modified with waste oligomer resin from phenol production, were studied by means of i.r. and ESR spectroscopy and thermal analysis. In the process of curing synthesized polymers with hexamethylene tetramine, the latter was found to decompose giving dimethyleneimine and other products causing cross-linking of the polymers. Incorporation of nitrogen in the polymer was proved by means of i.r. spectra and elemental analysis. The activation energy of decomposition was determined by thermogravimetry. Analysis of ESR spectra suggested that free radical processes participate in curing and decomposition of phenol-formaldehyde polymers modified with waste phenol resin.     

Regulating aspects of biosoluble and insoluble film release systems containing protein proteinase inhibitor

New types of potent aprotinin-containing medicinal polymer films are elaborated for topical applications. The higher the temperature of drying, the lower the steam absorption, the film swelling, and the velocity of aprotinin in vitro release. The presence of antimicrobials having the basic functional groups contributed to compacting the structure of the films and retention of aprotinin in them. The velocity of aprotinin release from the films is regulated by adding different polymers. Inclusion of polyvinylpirrolidone in the film resulted in acceleration and increase of aprotinin release. This was probably because of increasing the film swelling by a factor of 1.7. Additional retention of the inhibitor in films was achieved by inclusion of sodium alginate and cellulose powder capable of binding aprotinin. Soluble bioadhesive films derived from a copolymer of acrylamide,N-vinyl-pirrolidone, ethyl acrylate (M _r 30,000-600,000) and aprotinin were obtained and analyzed. Kinetics of aprotinin release from biosoluble films was studied under various conditions. The duration of aprotinin release was comparable with duration of gradual dissolution of the matrix. Bioavailability of aprotinin from soluble films was linear with time.     

31P NMR study of the hydrolytic activity of ethriol phosphite and triphenyl phosphite in a two-phase system

The hydrolytic activity of ethriol phosphite and triphenyl phosphite in the p-xylene/water two-phase system was studied by the³¹P NMR method. It was shown that the rate of hydrolysis can be controlled by varying the pH of the aqueous phase. Hydrolysis of triphenyl phosphite is much slower than that of ethriol phosphite in the tested pH range. Coordination of ethriol phosphite with a rhodium carbonyl complex completely suppresses its hydrolysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1026–1030, May, 1991.