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Double adducts of norbornadiene-2,5 and anthracene derivatives have been synthesized using the Diels–Alder reaction. The possibility of selective preparation of both symmetrical and unsymmetrical adducts depending on the reaction conditions has been shown. For these cycloadducts exclusively consisting of carbon and hydrogen, an unusual and interesting feature has been revealed, namely, the signals of the protons of the bridge methylene groups in the 1H NMR spectra have chemical shifts in the negative region. In this work, double adducts of anthracene derivatives and norbornadiene (2,5-(bicyclo-[2.2.1]-hepta-2,5-diene)) have been synthesized and their structure investigated. The synthesized compounds possess a rigid, branched, and bulky structure suitable for the fabrication of composite membrane materials.

Toxic effect of 2-ethylnorbornane (2-ethyl(bicyclo[2.2.1]heptane) (EBH)) on bacteria has been studied using the E. coli pRecA-lux and E. coli pKatG- lux cells as lux-biosensors. It was shown that the addition of EBH to the incubation medium leads to death and growth retardation, high level oxidative stress and DNA damage in E. coli cells. It is assumed that the oxidation of EBH with atmospheric oxygen causes the formation of reactive oxygen species in the medium, which makes a major contribution to the toxicity of this substance. biosensor, luciferase, bioluminescence, inducible promoter, PrecA, PkatG The authors are grateful to Stanislav Filippovich Chalkin for the development of interdisciplinary ties in the scientific community. The work was financially supported by the Ministry of Higher Education and Science of Russia (Project Unique Identifier RFMEFI60417X0181, Agreement No. 14.604.21.0181 of 26.09.2017).

[This corrects the article DOI: 10.1371/journal.pone.0228525.].

Here we present the study of the genotoxic effect of a 2,2’-bis(bicyclo[2.2.1]heptane) (BBH), which is promising as a fuel component for liquid rocket engines. The use ofEscherichia coli lux-biosensors showed that in addition to DNA damage causing SOS-response, there is also an oxidative effect on cells. The greatest toxicity is determined by the mechanism of formation of superoxide anion radical and is detected by the lux biosensorE. colipSoxS-lux, in which the genes of bacterial luciferases are transcriptionally crosslinked with the promoter of thesoxSgene. It is assumed that the oxidation of BBH leads to the formation of reactive oxygen species, which should give the main contribution to the toxicity of this substance.

The toxic effect of strained hydrocarbon 2,2'-bis (bicyclo[2.2.1]heptane) (BBH) was studied using whole-cell bacterial lux-biosensors based on Escherichia coli cells in which luciferase genes are transcriptionally fused with stress-inducible promoters. It was shown that BBH has the genotoxic effect causing bacterial SOS response however no alkylating effect has been revealed. In addition to DNA damage, there is an oxidative effect causing the response of OxyR/S and SoxR/S regulons. The most sensitive to BBH lux-biosensor was E. coli pSoxS-lux which reacts to the appearance of superoxide anion radicals in the cell. It is assumed that the oxidation of BBH leads to the generation of reactive oxygen species, which provide the main contribution to the genotoxicity of this substance.

High-energy-density (HED) liquid fuels are required for modern and perspective volume-limited aircrafts to extend the flight distance and to increase the speed. In this work, we report on the synthesis of a new set of HED liquid polycyclic norbornane-containing hydrocarbons and on the study of their key physico-chemical characteristics. A facile route to the desired hydrocarbons was developed through modifications of a cheap commercial diene, 5-vinyl-2-norbornene, using [2 + 2]- and [4 + 2]-cycloaddition reactions. Physico-chemical properties of the obtained hydrocarbons, such as density, freezing point, viscosity and heat of combustion, were systematically studied. Some of the hydrocarbons exhibited an enhanced combination of the properties: high heats of combustions, densities up to 1.0799 g/mL, freezing points in the range of +15 °C to below −60 °C and kinematic viscosities up to 1.89 mm2·s−1. The successive modifications of 5-vinyl-2-norbornene significantly improved the energy density (≤45.38 MJ/L) of the produced hydrocarbons over the widely used related fuel, JP-10. Thus, the developed norbornane-containing hydrocarbons can be considered as new promising HED liquid fuels for advanced propulsion.

The possibility of selective hydrogenation of 5-vinyl-2-norbornene to 2-vinylnorbornane with hydrazine hydrate in the presence of an oxidant (oxygen or air oxygen) and a hydrazine hydrate decomposition catalyst has been investigated. It has been shown that the hydrazine hydrate/oxidant/catalyst system makes it possible to hydrogenate the endocyclic (norbornene) double bond of 5-vinyl-2-norbornene to form 2-vinylnorbornane with a selectivity of up to 95% at the 5-vinyl-2-norbornene conversion above 99%. As catalysts for the oxidative decomposition of hydrazine hydrate, Pd/C and copper salts have been tested. The influence of the conditions of 5-vinyl-2-norbornene hydrogenation to 2-vinylnorbornane on the selectivity of the process and the product yield has been studied. An optimized and preparatively convenient procedure for the selective production of 2-vinylnorbornane has been developed.

Previously unknown 6-acetyl-10-aryl-5-hydroxy-4-methyl-9,10-dihydropyrano[2,3-f]-chromene-2,8-diones were synthesized by multicomponent condensation of 6-acetyl-5,7-dihydroxy-4-methylchromen-2-one, aromatic aldehydes, and Meldrum´s acid. A fundamen-tal possibility of interconversion of substituted 6-acetyl-10-aryl-5-hydroxy-4-methyl-9,10-dihydropyrano[2,3-f]chromene-2,8-diones and methyl 3-(6-acetyl-5,7-dihydroxy-4-meth-yl-2-oxo-2H-chromen-8-yl)-3-arylpropionates was demonstrated.

The synthesis and structure of the substituted trioxane compound 2,4,6,-tri­cyclo­butyl-1,3,5-trioxane is described. The three cyclo­butane rings attached to the 1,3,5-trioxane six-membered ring are all in a cis arrangement. The compound may find application as a stable trimeric form of the fragile cyclo­butane carbaldehyde., The synthesis and structure of 2,4,6,-tri­cyclo­butyl-1,3,5-trioxane, C15H24O3 1, is described. It was formed in 39% yield during the work-up of the Swern oxidation of cyclo­butyl­methanol and may serve as a stable precursor of the cyclo­butane carbaldehyde. The mol­ecule of 1 occupies a special position (3.m) located at the center of its 1,3,5-trioxane ring. The latter is in a chair conformation, with the symmetry-independent O and C atoms deviating by 0.651 (4) Å from the least-squares plane of the other atoms of the trioxane ring. All three cyclo­butane substituents, which have a butterfly conformation with an angle between the two planes of 25.7 (3)°, are in the cis conformation relative to the 1,3,5-trioxane ring. Inter­molecular C—H⋯O inter­actions between the 1,3,5-trioxane rings consolidate the crystal structure, forming stacks along the c-axis direction. The crystal studied was refined a as a racemic twin.

Sorption and membrane properties of metathesis and addition polymers based on 5-(2’-norbornanyl)- norbornene were studied. The desired monomer was prepared from 5-vinyl-2-norbornene by its selective hydrogenation to 2-vinylnorbornane followed by Diels-Alder reaction with dicyclopentadiene. Metathesis polymer was prepared in the presence of the first generation Grubbs catalyst. Addition polymerization was realized using a three component catalytic system consisting of Pd(OAc)2 (precatalyst), NaBARF (cocatalyst, Na+[B(3,5-(CF3)2C6H3)4]-) and a phosphine (tricyclohexylphosphine). The prepared polymers are high-molecular-weight, glassy and amorphous products. The polymers were isolated in good or high yields. Both synthesized metathesis and addition polymers showed good solubility in common organic solvents and thin, robust films were readily prepared via the solution casting method. The performed preliminary investigations showed that it is possible to obtain polymeric materials possessing large BET surface area (up to 500-700 m2/g) and promising gas-transport properties from norbornene derivatives with bulky and rigid carbocyclic groups.

A norbornane derivative, exo-tetrahydrodicyclopentadiene, is the main component of the high-density liquid fuel called JP-10. In the current communication we describe the preparation of some related norbornane-containing hydrocarbons and their energetic properties. The desired hydrocarbons were readily obtained in high yields using Diels-Alder and/or cyclopropanation reactions from the industrially available 5-vinyl-2-norbornene. As a result, the hydrocarbons containing two norbornane moieties or norbornyl and cyclopropyl groups were prepared. The heats of combustion, densities and freezing points of the prepared norbornane derivatives were evaluated. High densities in the range of 0.856–0.977 g/cm3 and low freezing points (below −60 °C) were found for the obtained hydrocarbons. By altering the structure of such a hydrocarbons, the energy density as high as 41.24 MJ/L was achieved. The energy densities for the hydrocarbons consisting of two norbornane moieties or norbornyl and cyclopropyl fragments were noticeably higher than that of JP-10. Taking into account the low freezing points, high densities and high energy densities, the developed norbornane-type hydrocarbons can be considered as a promising components for high-energy density liquid propellants.

The herein obtained 3-methyl-5,5-diphenylpyrimidine-2,4-(3H,5H)-dione forms upon photolysis an unusual bicyclic product, namely, 6-methyl-3,3,8,8-tetraphenyl-8,8a-dihydroimidazo[1.5-c]pyrimidine-5,7(3H,6H)-dione in 21% yield. The transformation starts with elimination of carbon monoxide and methyl isocyanate from the molecule of substrate via a ‘Type A’ photochemical process giving 3,3-diphenylazirine. Then 1,3-dipole species generated from the latter is trapped by the starting compound via a [3 + 2] cycloaddition.

A number of benzothiazolylthienothiophenes have been synthesized. Spectral studies have revealed that all these compounds have fluorescent properties that depend on their structure. Dependence of absorption and fluorescence bands positions on the nature of substituents have been established. Increase of the electron-withdrawing nature of substituents led to bathochromic shift of the absorption and fluorescence bands as well as to decrease of the fluorescence intensity.

The Type-A photochemistry of cyclohexadienones is well-studied and follows a well-established mechanistic pathway. One early example is the rearrangement of santonin to lumisantonin. Another example is the rearrangement of 4,4-diphenylcyclohexa-1,5-dienone. Remarkably, replacement of one carbon by nitrogen alters the reaction course to give a regioselective phenyl migration.

2,3-Diphenyl-1-naphthol (1) undergoes two unexpected reactions under different conditions. Compound (1) was heated in DMSO-d6 and underwent a Pummerer type thermal reaction to give two isomeric products, 1-(methylthio)methoxy-2,3-diphenyl naphthol-d5 which crystallized in the space group $$ P{\bar{\text{1}}} $$ with a = 7.1610(9) A, b = 11.2795(15) A, c = 12.8905(17) A, α = 114.049(2)°, β = 96.589(2)°, and γ = 102.945(2)°, and 2-(methylthio)methyl-2,3-diphenyl 1(2H)-naphthalenone-d5 which crystallized in the space group $$ P{\bar{\text{1}}} $$ with a = 8.5981(5) A, b = 10.4374(6) A, c = 11.1078(6) A, α = 78.748(2)°, β = 67.709(2)°, and γ = 83.184(2)°. Photolysis (254 nm) of (1) resulted in 2,2′,3,3′-tetraphenyl-1,1′-bi-2-naphthol which crystallized in the space group P21/c with a = 26.3616(11) A, b = 10.1707(4) A, c = 23.3376(9) A, and β = 99.034(2)°. When 2,3-diphenyl-1-naphthol was heated in DMSO-d6 two unexpected isomers, 1-(methylthio)methoxy-2,3-diphenyl naphthol-d5 and the racemate 2-(methylthio)methyl-2,3-diphenyl 1(2H)-naphthalenone-d5 were produced. Photolysis in THF at 254 nm led to the unexpected product 2,2′,3,3′-tetraphenyl-1,1′-bi-2-naphthol. All structures were elucidated by X-ray crystallography.

3-Nitromethylpyrazolidine reacts with derivatives of unsaturated acids and reducing agents with the formation of polyfunctional compounds of the pyrazolidine nucleus.

A convenient method has been developed for the synthesis of previously unknown photochromic 1-amino-3-[1-(2,5-dimethyl-3-thienyl)ethylidene]-4-(1-methylethylidene)pyrrolidine-2,5-dione, from which photochromic Schiff’s bases were obtained. A spectral kinetic investigation of the photochromism of the thienylfulgimides obtained has been carried out.

A convenient procedure has been developed for the synthesis of 3,4-diaryl(or hetaryl)maleimides by cross coupling of N-substituted 3,4-dibromomaleimides with aryl(hetaryl)boronic acids in the presence of Pd(Ph3P)4 and CsF. The reaction ensures high yields of the products and requires relatively small amount of the catalyst; it can be performed on an enlarged scale. The resulting maleimides are readily converted into the corresponding maleic anhydrides.

The condensation of 3-nitro-5-carboxy-2-methylthiophene with acetals of amides proceeds smoothly, and further ammonium formate–Pd/C reduction of nitroenamines thus obtained affords 2-carboxythieno-(5-R)-[3,2-b]pyrroles (R = H, Me) in good yields.

N-tert-Butyloxycarbonylamino-3-[Z-α-(2,5-dimethyl-3-thienyl)ethylidene]-4-isopropylidenepyrrolidine-2,5-dione was prepared in 80% yield from the corresponding isomeric hydrazidic acids using N,N'-carbonyldiimidazole, whereas a number of other cyclisation reagents were ineffective.

Palladium-catalyzed cross-coupling between 2,5-dimethyl-3-thienylboronic and mucobromic acids under phase transfer catalysis (PTC) conditions gave the expected 3,4-bis(2,5-dimethyl-3-thienyl)-5-hydroxyfuran-2-one in 32% yield. The by-product was 2,2’,5,5’-tetramethyl-3,3’-bithiophene. The oxidation of the obtained hemiacylal with potassium permanganate under PTC conditions afforded 3,4-bis(2,5-dimethyl-3-thienyl)furan-2,5-dione in high yield.