Cycloaliphatic Ring Research Articles

Synthetic approach to spiropyranocoumarins and their oxime derivatives

This study explores the synthesis of a diverse series of linear (spiro)pyranocoumarins and their corresponding oximes, compounds known for their promising biological activities. Building on previous work, the authors expand the array of target compounds, adding structural features such as dimethyl groups and various cycloaliphatic rings. The novel synthetic procedure applied herein couples o-hydroxyacetyl coumarins with respective ketones via Kabbe condensation, yielding 16 derivatives, including 12 new compounds. A further step engages these (spiro)pyranocoumarins with hydroxylamine hydrochloride, leading to oximes, selectively at the exocyclic oxygen atom of the chroman-4-one fragment. Optimizing synthesis conditions has increased product yields and reduced reaction times. Acidic hydrolysis of select compounds introduces additional carbonyl groups and facilitates deprotection, while the subsequent reaction with hydroxylamine hydrochloride produces dual-oxime compounds. These findings contribute to the ongoing development of pyranocoumarin and oxime-based therapeutics, with potential applications in treating various diseases

Controlling spontaneous mirror symmetry breaking in cubic liquid crystalline phases by the cycloaliphatic ring size.

Rod-like molecules combining a fork-like triple chain end and a cycloaliphatic apex are introduced as a new design concept for materials with broad ranges of bicontinuous cubic (Cubbi) phases. By ring expansion from n = 4 to 12 a sequence of three Cubbi phases is observed; the achiral double gyroid la3[combining macron]d phase, a chiral "Im3m" phase and an achiral re-entrant la3[combining macron]d phase. The chiral "Im3m" phase is formed if the helical twist between the molecules along the networks is in the range of 8.6°-9.5°, either for the individual compounds or their mixtures.

Ruthenium(II)‐Chitosan, an Enantioselective Catalyst for the Transfer Hydrogenation of N‐Heterocyclic Ketones

AbstractThe present study aimed at extending the applicability of a recently developed stereoselective catalytic system to the preparation of optically enriched N‐heterocyclic alcohols. Chiral ruthenium catalyst formed in situ using the chitosan biopolymer as ligand, which provided good results in the transfer hydrogenation of heterobicyclic compounds, such as 4‐chromanone and 4‐thiochromanone, was used in reactions of various N‐containing prochiral ketones. High enantioselectivities were reached in transfer hydrogenations of bicyclic compounds bearing nitrogen either in aromatic or cycloaliphatic moieties, provided that the amino group was protected or shielded by a nearby substituent. Results were rationalized by interactions of the nitrogen with the metal and/or ligand. N‐containing bicyclic compounds having heteroatoms in both rings were also prepared and tested. The detrimental effect of the pyridyl moiety was compensated by the beneficial influence of the heteroatom in the cycloaliphatic ring, as indicated by high rates and good enantioselectivities obtained in reactions of these compounds. Preparation of several N‐heterocyclic alcohols, in good yields and high optical purities was achieved using Ru(II)‐chitosan complex.

The influence of 1,4-cyclohexanedicarboxylic acid on the thermal and mechanical properties of copolyamides

The present paper describes the novel aliphatic polyamide 6 (PA6) copolyamides by the melt polymerization reaction of our newly synthesized aliphatic diamine monomer: N1,N6-Bis-(2-aminoethyl)adipamide (BAEA). The BAEA/CHDA (1,4-cyclohexanedicarboxylic acid) salt was prepared by pertinent long-chain polyamide with the cycloaliphatic ring and isolated as white solid, utterly characterized for the first time. The chemical structure of BAEA, BAEA/CHDA salt and copolyamides (PA6-BAEA/CHDA) was identified by 1H NMR and FT-IR spectroscopy. Depending on the chemical compositions, the viscosity and molecular weight of the copolyamides were in the range of 19,447–13,536 g mol−1 and 2.74–2.2 dL g−1. With increasing BAEA/CHDA salt molar ratio in the synthesized copolyamides, their melting temperatures (Tm) decreased from 212.7 to 170.4 °C, and the glass transition temperatures (Tg) increased from 60 to 89.4 °C. Besides, the as-synthesized all copolyamides possess nearly similar thermal stability (Td-50% = 439.59 − 443.38 °C) as neat PA6. Mechanical testing data revealed that with an increase in a proportion of BAEA/CHDA salt, Young’s modulus of copolyamides is increased from 698.54 to 1093.89 MPa, while the tensile strength is increased by 8.1%.

Complete genome sequence of Bacillus sp. HBCD-sjtu, an efficient HBCD-degrading bacterium.

Environmental pollution caused by the release of industrial chemicals is currently one of the most important environmental harms. Manufacturing chemicals can be biodegraded, and valuable intermediates can be used as pharmacophores in drug targeting and have several other useful purposes. Hexabromocyclododecane (HBCD), a non-aromatic brominated flame retardant, is a toxic compound that consists of a cycloaliphatic ring of 12 carbon atoms to which six bromine atoms are attached. It is formed by bromination of cis-trans-trans-1,5,9-cyclododecatriene, but its use is now restricted in several countries, because it is an environmental pollutant. Little is known about whether bacteria can degrade HBCD. A bacterial strain that degrades HBCD was recently isolated using enrichment culture techniques. Based on morphological, biochemical and phylogenetic analysis this isolate was categorized as Bacillus cereus and named strain HBCD-sjtu. Maximum growth and HBCD-degrading activity were observed when this strain was grown at 30°C, pH 7.0 and 200 RPM in mineral salt medium containing 0.5mm HBCD. The genome of strain HBCD-sjtu, which consists of only one circular chromosome, was sequenced. This whole genome sequence will be crucial for illuminating the molecular mechanisms of HBCD degradation.

Fatty Acid Chain Combined with Cycloaliphatic Rings via Amberlyst‐15: A Promising Structure for a High Biocontent Epoxy Design

Fatty acid chain grafted with terpene rings via catalyst Amberlyst-15 has been demonstrated as a promising structure for the design of biobased epoxy, by which high biocontent (80 wt %) product with excellent optical (transmittance = 90%), mechanical (tensile strength = 64 Mpa) and processing (viscosity = 2.7 Pa s) properties were achieved through UV-curing in seconds. Additional Supporting Information may be found in the online version of this article. Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A metal–organic framework functionalized with piperazine exhibiting enhanced CH4 storage

NJU-Bai 19, the first cycloaliphatic ring (piperazine) functionalized MOF-505 analogue, exhibits a notably high methane storage capacity of 246 cm3 (STP) cm−3 (at room temperature and 65 bar) and a working capacity of 185 cm3 (STP) cm−3.

Competitive Adsorption of Naphthenic Acids and Polyaromatic Molecules at a Toluene–Water Interface

The early-stage competitive co-adsorption of interfacially active naphthenic acids (NAs) and polyaromatic (PA) molecules to a toluene-water interface from the bulk toluene phase was studied using molecular dynamics (MD) simulation. The NA molecules studied had the same polar functional group but different cycloaliphatic nonpolar tails, and a perylene bisimide (PBI)-based molecule was used as a representative PA compound. The results from our simulations suggest that the size and structural features of NA molecules greatly influence the interfacial activity of PA molecules and partitioning of NA molecules at the toluene-water interface. At low concentrations of PA (∼2.3 wt %) and NA (∼0.4 wt %) molecules, NA molecules containing large cycloaliphatic rings (e.g., four rings) or with a very long aliphatic tail (e.g., carbon chain length of 14) were observed to impede the migration of PA molecules to the interface, whereas small NA molecules containing two cycloaliphatic rings had little effect on the adsorption of PA molecules at the toluene-water interface. At high NA concentrations, the adsorption of PA molecules (∼5.75-17.25 wt %) was greatly hindered by the presence of small NA molecules (∼1.6-4.8 wt %) due to the solvation of PA nanoaggregates in the bulk. Adsorption mechanisms of PA and NA molecules at toluene-water interfaces were clarified through a detailed analysis on the interactions among different species in the system. The results obtained from this work provide insights into designing appropriate chemical demulsifiers or co-demulsifiers for breaking water-in-oil emulsions of great industrial applications.

New bio-based polymeric thermosets synthesized by ring-opening polymerization of epoxidized soybean oil with a green curing agent

New polymeric thermosets with a high bio-based content were obtained by the ring-opening polymerization of two biomass derivatives, epoxidized soybean oil and maleopimaric acid, catalysed by 2-ethyl-4-methylimidazole. Maleopimaric acid with a rigid hydrogenated phenanthrene ring structure was successfully synthesized in a large quantity from abietic acid and maleic anhydride using p-toluene sulfonic acid as a catalyst, by adapting and optimizing an industrial strategy. The advantages of using maleopimaric acid as a curing agent for epoxidized soybean oil, compared with its petroleum-based analogues, were studied in detail. The results showed that the total heat release for the ring-opening polymerization of epoxidized soybean oil and maleopimaric acid was only 31.7kJ/mol epoxy group. The tensile properties and glass transition temperature of the thermosets cured by maleopimaric acid were close to those of the products cured by the analogue with a cycloaliphatic ring, while the breaking elongation and storage modulus at room temperature of the former were greatly larger, exhibiting values of 61.5% and 1268MPa, respectively. Additionally, the products cured with maleopimaric acid had the best thermal stability with a 10%-weight-loss temperature up to 349°C and satisfactory chemical and water resistance.

Competitive Nucleophilic Attack Chemistry Based on Undecenoic Acid: A New Chemical Route for Plant-Oil-Based Epoxies

Plant oil is one of the world’s most abundant renewable resources; however, its derived epoxies are low in thermal resistance and mechanical strength. In this work, a new chemical route referred to “competitive nucleophilic attack (CNA)” was discovered to achieve plant-oil-based epoxy with high thermal resistance and mechanical strength as well as many other unique properties comparable to those of diglycidyl ether of bisphenol A (DGEBA), one of the most popular petroleum-based epoxies. The CNA route was realized by using 10-undecenoic acid (UA), a plant-derived monomer, as a building block reacting with alicyclic oxirane chemicals, such as 4-ethenyl-7-oxabicyclo[4.1.0]heptanes (ECP), to achieve epoxy monomers with ether-bridged cycloaliphatic ring structure. A newly formed hydroxyl (NFH) is involved in the nucleophilic attack upon oxonium to compete with UA anion during the UA–ECP reaction. The resultant epoxy is UV-curable in a few seconds, possessing high tensile strength (∼48 MPa), high glass transiti...

Novel dehydroepiandrosterone benzimidazolyl derivatives as 5α-reductase isozymes inhibitors

5α-R isozymes (types 1 and 2) play an important role in prostate gland development because they are responsible for intraprostatic dihydrotestosterone (DHT) levels when the physiological serum testosterone (T) concentration is low. In this study, we synthesized seven novel dehydroepiandrosterone derivatives with benzimidazol moiety at C-17, and determined their effect on the activity of 5α-reductase types 1 and 2. The derivatives with an aliphatic ester at C-3 of the dehydroepiandrosterone scaffold induced specific inhibition of 5α-R1 activity, whereas those with a cycloaliphatic ester (cyclopropyl, cyclobutyl, or cyclopentyl ring) or an alcohol group at C-3 inhibited the activity of both isozymes. Derivatives with a cyclohexyl or cycloheptyl ester at C-3 showed no inhibitory activity. In pharmacological experiments, derivatives with esters having an alcohol or the aliphatic group or one of the three smaller cycloaliphatic rings at C-3 decreased the diameter of male hamster flank organs, with the cyclobutyl and cyclopentyl esters exhibiting higher effect. With exception of the cyclobutyl and cyclopentyl esters, these compounds reduced the weight of the prostate and seminal vesicles.

Identification of the stereochemical requirements in the 4-aryl-2-cycloalkylidenhydrazinylthiazole scaffold for the design of selective human monoamine oxidase B inhibitors

Exploring the effect that substituents on the cycloaliphatic ring had on the inhibitory activity against human monoamine oxidase B of a series of 4-aryl-2-cycloalkylidenhydrazinylthiazoles led to the synthesis of a new series of 2-methylcyclopentyl and 3-methylcyclopentyl derivatives which were tested in vitro as mixtures of diastereoisomers. In fact, due to the presence of a chiral center on the cycloaliphatic ring and a trisubstituted CN bond, they exist as four diastereoisomers ((E)-(R), (E)-(S), (Z)-(R), (Z)-(S)). 4-(2,4-Difluorophenyl)-2-(2-(3-methylcyclopentylidene)hydrazinyl)thiazole was chosen as a model to investigate the influence of stereochemical requirements on the inhibitory activity against hMAO-B of these derivatives after a stereoconservative synthesis and semi-preparative HPLC diastereoseparation. (R)-(Z) isomer of this compound was endowed with a potent and selective hMAO-B inhibition higher than that of reference drugs as also corroborated by molecular modeling studies.

Synthesis and cytotoxicity of novel (thiazol-2-yl)hydrazine derivatives as promising anti-Candida agents

Thirty-eight new (4-(4-substituted-phenyl/2,4-disubstituted-phenyl)-thiazol-2-yl)hydrazine derivatives were synthesized in good yield and assayed for their in vitro anti-Candida activity, compared to topical and systemic antifungal drugs, against twenty-two clinical isolates of Candida spp. The concurrent presence of aliphatic chains or cycloaliphatic rings at N1-hydrazine and a 4-methyl/4-methoxyphenyl at C4 position of the thiazole nucleus exhibited an interesting anti-Candida inhibitory activity. Moreover, some of the most active compounds showed synergistic antifungal effects and lower cell toxicity when combined with clotrimazole.

Studies on quinones. Part 47. Synthesis of novel phenylaminophenanthridinequinones as potential antitumor agents

In our search for potential anticancer agents, a series of 8- and 9-phenylamino-3,4-tetrahydro-phenanthridine-1,7,10(2 H)-triones with substituent variations at 6-, 8- and 9-positions were prepared using a highly efficient sequence involving: a) solar photoacylation reactions of benzoquinone with arylaldehydes, b) one-pot procedure for the synthesis of 3,4-dihydrophenanthridine-1,7,10(2 H)-trione intermediates from acylhydroquinones and c) highly regiocontrolled acid-induced amination reaction of phenanthridinequinones with phenylamines. The members of this series were in vitro evaluated using the MTT colorimetric method against one normal cell line and three human cancer cell lines. The SAR analysis indicates that the location of nitrogen substituents on the quinone nucleus, the presence of methyl, phenyl, furyl and thienyl groups at the 6-position and the aromatization of the angular cycloaliphatic ring of the phenylamino-3,4-tetrahydrophenanthridine-1,7,10(2 H)-trione pharmacophore play key roles in the antitumor activity.

Chemical modification of unsaturated polyesters influence of polyester's structure on thermal and viscoelastic properties of low styrene content copolymers

AbstractIn this study, the chemical modification of unsaturated polyesters and the influence of polyester's structure on thermal and viscoelastic properties have been presented. The structure of unsaturated polyesters obtained in polycondensation of cyclohex‐4‐ene‐1,2‐dicarboxylic anhydride (THPA), maleic anhydride and only one suitable symmetrical glycol: ethylene glycol or 1,4‐butanediol (BDO) or 1,6‐hexanediol has been modified by peracetic acid. The selective oxidation of unsaturated polyesters conducted in mild time and temperature conditions was a successful and effective method to prepare new materials/unsaturated epoxy polyesters/containing epoxy groups in cycloaliphatic rings and carbon–carbon double bonds in polyester chain. The unsaturated epoxy polyesters were capable of both copolymerization with vinyl monomer and polyaddition reactions with suitable curing agent. Therefore, they were successfully used as a component of low styrene content copolymers. As was confirmed by DSC, DMA, and TGA analyses, polyester's structure had significant influence on thermal and viscoelastic properties of styrene copolymers. The properties of styrene copolymers prepared from unsaturated epoxy polyesters were considerably better compared with those obtained for styrene copolymers from unsaturated polyesters.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The influence of chemical modification of unsaturated polyesters on viscoelastic properties and thermal behavior of styrene copolymers

The influence of chemical modification of unsaturated polyesters on viscoelastic properties and thermal behavior of styrene copolymers has been investigated by DMA and TG analyses. Chemical modification of unsaturated polyesters obtained in polycondensation of cyclohex-4-ene-1,2-dicarboxylic anhydride (THPA), maleic anhydride (MA) and suitable glycol: diethylene glycol (DEG) or triethylene glycol (TEG) was performed using 38–40% peracetic acid. It allowed to selective and successful oxidation of carbon-carbon double bonds in unsaturated polyesters giving modified unsaturated polyesters/unsaturated epoxypolyesters/containing both carbon-carbon double bonds in polyester chain and new functional groups-epoxy groups in cycloaliphatic rings. Both unsaturated polyesters and unsaturated epoxypolyesters were used as a component of styrene copolymers cured with different hardeners. It has been demonstrated that the use of modified unsaturated polyesters as a component of styrene copolymers allowed obtaining more stiffness and more cross-linked network structure compared to styrene copolymers based on unmodified polyesters. The higher values of storage modulus, glass transition temperatures and better thermal stability for styrene copolymers based on unsaturated epoxypolyesters were obtained.

Materials for lithography in the nanoscale

Design and development of photoresists aiming at patterning in the nanoscale is reported. Functionalised polycarbocycle-based molecules and Polyhedral Oligomeric Silsesquioxane (POSS) containing (meth)acrylate copolymers are the basic components of the resist materials proposed for 193 nm and EUV lithography. The synthesis of new functionalised polycarbocycles aimed first at the development of etch resistance additives for 193 nm (meth) acrylate resists, since these compounds are characterised by moderate absorbance at 193 nm and by increased etch resistance due to the polyaromatic and cycloaliphatic rings they contain. Recently, additional functionalisation with appropriate imaging and hydrophilic groups advanced compounds of this class to become suitable main components of molecular resist compositions. On the other hand the incorporation of POSS groups in (meth)acrylate copolymers was studied first towards the development of 157 nm double layer resists, and recently, after the renewal of the semiconductor industry interest for 193 nm technology for double layer 193 nm resists. Characterisation methodologies for sub 100 nm thick resist films were also developed based on interferometry and used for the optimisation of the resist materials developed.

Stereochemistry Driven Distribution of 1,4-Diaminocyclohexane Residues over the Crystalline and Amorphous Phase in Copolyamides 4.14/1,4-DACH.14. A Solid-State NMR and Temperature-Dependent WAXD Study

Following our previous study on the stereoselective cocrystallization of linear and cyclic dicarboxylic acid residues in copolyamides 12.6/12.1,4-cyclohexanedicarboxylic acid (12.6/12.1,4-CHDA, Vanhaecht et al., Macromolecules 2004, 37, 421), we have now investigated a series of copolyamides containing trans or cis isomers of 1,4-diaminocyclohexane (1,4-DACH), viz. 4.14/1,4-DACH.14. Solid-state NMR studies and WAXD experiments demonstrate that the cis isomer is present in the amorphous regions of the copolyamide, whereas the trans isomer is located in both the crystalline and the amorphous phase. Similar to the results for the trans-1,4-CHDA-based copolyamides, trans-1,4-DACH moieties are probably built into the crystalline structure with the cycloaliphatic ring oriented perpendicular to the hydrogen-bonded crystal sheets. Temperature-dependent WAXD patterns show that, unlike in the homopolyamide 4.14, a pseudohexagonal phase is not formed at the Brill temperature in the copolyamide. Instead, crossing rat...

The intramolecular hydrogen bonds in some Schiff bases derived from cyclopropyl-, cyclobutyl- and cyclopentylamine

Eight Schiff bases ( N-(R-salicylidene)–cycloalkilamines, R=H, 5-NO 2 and 5-Br) obtained from cyclopropyl, cyclobutyl- and cyclopentylamine were investigated in terms of intramolecular hydrogen bond formation in chloroform solution and in the solid state. The relationship between cycloalkyl ring size and proton position was discussed. For the compounds which exist as OH form (salicylaldehyde and 5-bromosalicylaldehyde derivatives), no correlation between ring size and proton position in hydrogen bond was found. For 5-nitro derivatives, the structure of hydrogen bridge strongly depends on the cycloaliphatic ring size.

A WAXD and Solid-State NMR Study on Cocrystallization in Partially Cycloaliphatic Polyamide 12.6-Based Copolymers

To study the influence of the stereochemistry on the possibility of cocrystallization of linear and cyclic aliphatic residues in copolyamides, a series of copolyamides 12.6/12.1,4-cyclohexanedicarboxylic acid with variable compositions were synthesized. From solid-state NMR studies it could be deduced that cis-1,4-CHDA is present in the amorphous regions whereas the trans residues are located in both the crystalline and the amorphous phase. WAXD patterns confirm the presence of trans-1,4-CHDA inside the crystals and reveal that the cycloaliphatic ring is most likely oriented in a direction perpendicular to the crystal sheets that contain the hydrogen bonds. As a result, the intersheet distance is increased compared to that of polyamide 12.6. Furthermore, the rings prevent the genesis of a pseudohexagonal phase above the Brill temperature. Exceptionally, crossing rather than merging of the (100) and the combined (010)−(110) WAXD reflections is observed with increasing temperature, indicating that the inter...