This review summarizes the data on the synthesis of novel axially chiral or differently chiral platinum, iridium, and molybdenum complexes, porphyrin derivatives, ...subphthalocyanine–tetracyanobutadiene conjugates with unique photophysical properties, small carbo(hetero)cyclic and acyclic molecules, and phosphabarrelenes. Synthetic approaches to some atropisomeric representatives of macrocycles and cyclophanes are considered. New examples of cyclizations are presented, where the induction of chiral sites is controlled by the stereoisomerism or axial chirality of the substrate molecules in their reactions with electrophilic, nucleophilic, and radical-forming reagents and metal complexes, as well as in inter- or intramolecular cycloaddition reactions. Attention is also paid to the atroposelective conversion of münchnones generated from
ortho
-(alkenyl)phenyl-substituted
N
-acylglycines, where rotation about the N–Ar bond is hindered.
The effect of γ-irradiation of the gelling agent Carbomer 141G, which is lightly crosslinked polyacrylic acid, on the rheological properties of gels based on the carbomer has been studied. It has ...been found that an increase in the dose of γ-irradiation in air has a destructive effect on the polymer, leading to a decrease in rheological parameters, such as viscosity, yield strength, and hysteresis area. Irradiation of the carbomer in air with doses greater than 300 kGy leads to a significant decrease or the complete loss of its gel-forming properties. At the same time, irradiation of the carbomer with the same dose in vacuum causes as small a decline in viscosity as 2% compared to the initial systems. It has been established that the optimal gelling agent for obtaining stable antibacterial gels is the carbomer irradiated with a dose of 30 kGy.
The findings of platinum group metal mineralization (PGM) and the distribution of platinum group elements (PGE) in lherzolites of the Northern Kraka massif are described. The total contents of PGE ...are approximately two orders of magnitude lower than those in chondrite and are close to pyrolite, relative to which the studied lherzolites are enriched in Pd and depleted in Ru. In segregations of PGMs, the presence of all PGEs (except rhodium) in various proportions was established. All found grains are divided into three contrasting types: the refractory triad Os–Ir–Ru, essentially platinum with the participation of Pd, and Cu–Pd. Almost all found PGM grains are localized either in the peripheral parts of grains of altered sulfides (heazlewoodite, pentlandite) or in the silicate matrix in the immediate vicinity of sulfide segregations. Based on the mineral associations and PGE distribution, a probable genesis of segregations has been suggested. Associations of Cu–Pd and Pd–Pt(+Cu) composition most likely formed during the crystallization of sulfides from the extracted partial melts. This is indicated by their close association with clinopyroxenes and the presence of relatively fusible platinoids and copper. The associations of Pt–Ir and Os–Ir–Ru(+Pt) composition are most likely restitic, formed in place of primary mantle sulfides as a result of extraction of more fusible elements and further desulphurization. The isolation of platinoids as their own mineral phases is associated with the influence of superimposed low-temperature processes – subsolidus redistribution during cooling and subsequent serpentinization.
The effect of γ-irradiation on the acute toxicity of commercial lightly crosslinked polyacrylic acid of the trademark Carbomer 141G and a gel based on it has been studied by intraperitoneal, ...cutaneous, and oral administration to experimental Balb/c and C57BL/6 mice. Preliminary γ-irradiation of the carbomer decreased the toxicity of its aqueous dispersion upon intraperitoneal administration. At the same time, the dynamics of body weight of experimental animals showed a significant decrease (
p
= 0.05) in average body weight 2–3 days after the introduction of aqueous dispersions of both nonirradiated and irradiated carbomer with a tendency to restore body weight by 14 days; dispersions with a high carbomer content led to death. Unlike the oral administration of gels, when a decrease in the weight of experimental animals was observed, an increase in the weight of the experimental animals was observed from the very first days of the experiment in the case of cutaneous administration of gels, and their death did not occur. The addition of carbon nanotubes (CNTs) (0.07 wt %) and fullerene C60 (0.10 wt %) to the gels led to a decrease in the average weight gain of animals upon both oral and cutaneous administration of the gels without causing a toxic effect on the body. Studies of the acute toxicity of the original carbomer and its γ-irradiated analogue up to 1000 kGy allowed them to be classified as hazard class 3 for the intraperitoneal route of administration in accordance with GOST State Standard 12.1.007–76. The results of this study indicate that polymer gels based on lightly crosslinked polyacrylic acid (in irradiated and nonirradiated forms) can be used as carriers of active drug components for targeted delivery in the treatment of socially significant diseases.
The review covers the results of studies published in the literature on the synthesis of spiro‐linked heterocycles of the indole, quinoline, benzoxazine, benzothiazine, indenoquinoxaline, ...pyridopyrimidine, and acridine series. Possible approaches to the synthesis of spirocycles through a sequence of well‐known Knoevenagel, Michael reactions, deamination cyclization of 1,2‐dicarbonyl, CH‐acid compounds, direct cycloaddition of activated olefins to isatins, 3‐alkylideneindoles, 2‐oxindoles, in situ generated azomethine ylides, indenoquinoxalines are analyzed. Attention is drawn to approaches to the preparation of spiro‐fused compounds using reactions of intra‐ and intermolecular dearomatization of indoles. Recent advances in the synthesis of spiro‐linked benzo heterocycles from derivatives of 2‐olefin substituted anilines are summarized. The examples of the synthesis of spiro‐fused heterocycles by means of metal complexes catalyzed decomposition of diazo compounds are given. Some syntheses of biologically active representatives are shown, as well as the use of transformations of spiroheterocycles in the preparation of other heterocycles.
The article describes an efficient access to cycloalkene-annulated benzoxazocines displaying both axial and central chiralities, via a domino halogenation-lactonization reaction of substituted ...glycine precursors. Upon interaction between N-2-(1-cyclohexen-1-yl)-6-methylphenyl-N-mesyl- or -N-arylsulfonylglycines and bromine an axially chiral mixture of (aR,R)- and (aS,S)-enantiomers of heterocycles with benzoecyclohexag1,4oxazocine core is formed as the main reaction product, which slowly transforms into the corresponding mixture of (aS,R)- and (aR,S)-enantiomers. The reaction of N-tosyl analog of these glycines with iodine under the same conditions leads to the heterocycle of spiro4,1-benzoxazepin-5,1′-cyclohexane structure. Upon treatment of the cyclopentenyl homologue N-tosylate of these glycines with molecular bromine or iodine, in both cases, a compound with the benzoxazocinone backbone is obtained as the only reaction product.
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The effect of chitosan (200 kD, 75% deacetylation) on
Nosema apis
development in bee colonies during wintering was investigated. The conditions for development of the nosematous infection were ...analyzed. According to the results of determination of PCR products specific for
N. apis,
chitosan decreased significantly the degree of infection of individual bees with
N. apis
spores. The scheme of stimulation of the bee immune system by chitosan via the changes in the level of antimicrobial peptides and proteins of the macroorganism antioxidant systems is discussed. Due to a decrease in the degree of infection with
N. apis
, survival of the bees increased during the long winter period.
This review summarizes the data on the synthesis of novel axially chiral or differently chiral platinum, iridium, and molybdenum complexes, porphyrin derivatives, ...subphthalocyanine–tetracyanobutadiene conjugates with unique photophysical properties, small carbo(hetero)cyclic and acyclic molecules, and phosphabarrelenes. Synthetic approaches to some atropisomeric representatives of macrocycles and cyclophanes are considered. New examples of cyclizations are presented, where the induction of chiral sites is controlled by the stereoisomerism or axial chirality of the substrate molecules in their reactions with electrophilic, nucleophilic, and radical-forming reagents and metal complexes, as well as in inter- or intramolecular cycloaddition reactions. Attention is also paid to the atroposelective conversion of münchnones generated from ortho-(alkenyl)phenyl-substitutedN-acylglycines, where rotation about the N–Ar bond is hindered.
The major product of intramolecular 3 + 2-cycloaddition of münchnones generated by heating
syn
- and
anti
-atropisomers of
N
-acetyl-
N
-2-(cyclopent-2-en-1-yl)-6-methyl-, 2,4-dimethyl-, ...2,5-dimethylphenyl)- and
N
-acetyl-
N
-2-(cyclohex-2-en-1-yl)-6-methylphenylglycines with acetic anhydride was that formed from the anti isomer. Isomeric glycine derivatives having no methyl group in the
ortho
position of the aromatic ring gave rise to (1
S
*,3a
R
*,4
S
*,7
S
*,13
S
*)-1-methyl- and (1
S
*,3a
R
*,4
S
*,7
S
*,13
S
*)-3a-acetyl-1-methyl-4,5,6,7- tetrahydro-1,4,7-epimethanetriyl1,3oxazolo3,4-
a
1benzazocin-3(3a
H
)-one as the major product. Treatment of 1,11-dimethyl- and 1,9,11-trimethyl-4,5,6,7-tetrahydro-1,4,7-epimethanetriyl1,3oxazolo3,4-
a
1benzazocin- 3(3a
H
)-ones with methylamine in methanol on heating in a sealed ampule afforded epimethanetriylimidazobenzazocinones, whereas acid-stable compound with a methanocyclopenta
c
quinoline skeleton was formed under similar conditions from the 1,8,11-trimethyl analog.
The reactions of
N
-2-(cyclohex-1-en-1-yl)-6-methylphenylarenesulfonamides and
N
-2-(cyclohex-1-en-1-yl)phenylmethanesulfonamide with molecular bromine in the presence of ethylene chlorohydrin ...afforded mixtures of
N
-{2-6-(2-chloroethoxy)cyclohex-1-en-1-ylphenyl} sulfonamides and 9-(arenesulfonyl)- or 9-(methanesulfonyl)-2,3,9,9a-tetrahydro-1
H
-carbazoles. Intramolecular condensation of the obtained 2-chloroethyl ethers in the presence of potassium hydroxide and benzyl(triethyl)ammonium bromide in THF gave 8-(arenesulfonyl)-9-methyl-2,4,4a,6,7,8-hexahydro-3
H
-dibenzo
e
,
g
1,4oxazocines as a result of formation of new nitrogen–carbon bond. The presence of a methyl group at C
9
of the aromatic ring gives rise to axial isomerism of the synthesized benzoxazocines. The major conformer of the cyclocondensation products has a
S
*,
R
* configuration of the heterocycle, and this conformer slowly isomerizes to the a
R
*,
R
* conformer at room temperature.
