Dioxin Derivatives Research Articles

Intramolecular cyclization of the product of iodo-alkoxylation with 3,4-dihydro-2H-pyrano dimethylacetylene carbinol and with its Csp-substituted derivatives

As a result of the research of the reaction of 3,4-dihydro-2H-pyrano-dimethylacetylene carbinol (also with its Csp-substituted derivatives) of iodo-alkylation on clinoptilolite in the presence of (NaK)4CaAl6Si30O72 and crystalline iodine, 3-iodine-2-[(2-methyl-4-organyl-but-3-in-2-yl)oxy]oxane was prepared. This method of preparation of heterocyclic compounds allows the reaction to be carried out in the absence of solvents, which reduces the amount of reagents and allows obtaining a product with high purity and high yield (67.5%). It was established that the latter under the conditions of the Kucherov reaction turn into heterocyclic compounds. Thus, effective regioselective methods for the synthesis of dioxin derivatives have been developed. This fact is probably related and is obviously explained by the intramolecular cyclization of the resulting intermediate-ketohydroxyester, i.e. tandem hydrolysis of C–I and hydration of CC bonds of the reaction products. The yield of 2-benzyl-3,3-dimethylhexahydro-4aH-piran[2,3-b][1,4]dioxin-2-ol is higher than that of structural analogues. It should also be noted that the synthesized compounds have an increased reactivity, and are rich in nucleophilic centers. Based on experimental data, it was established that the compounds obtained in this way are stable and do not undergo hydrolysis. Some physicochemical properties of the synthesized compounds were given, their composition and structure were confirmed by elemental analysis data, and all synthesized compounds were identified by IR and NMR spectroscopy.

Photodegradation of Triclosan on the Kaolinite Surface: Kinetic, Mechanistic, and Molecular Modeling Approach.

The photodegradation of triclosan (TCS) was investigated on the kaolinite surface. The quantum yield was evaluated, and the photoproducts were identified by HPLC/MS (LC/Q-TOF), showing that the phototransformation is completely different from that reported in aqueous solutions. In particular, the formation of dioxin derivatives was fostered and occurred with a higher efficiency when compared to aqueous solutions. This suggests that TCS has specific interactions with the clay that clearly modifies its photochemical behavior. Moreover, it has also been shown that higher concentrations of TCS, namely, higher than 1.0 μmol g-1 of kaolinite, lead to a significant decrease of the photodegradation rate constant and enhance the formation yield of dimer-type photoproducts. This suggests that the distribution of TCS is clearly not homogeneous at the clay surface and the formation of aggregates is more likely occurring. To get a better insight into this specific interaction, a molecular dynamic modeling of TCS adsorption at the surface of kaolinite was carried out. This clearly shows that when equilibrium is reached, TCS binds to the kaolinite surface by hydrogen bonds involving the phenol function of TCS and the hydroxyl groups of the kaolinite surface. Such behavior confers a particular conformation to the adsorbed TCS that is different from that obtained in water and which could be a key step to partially explain the specific photochemical reactivity in both media. In addition, several TCS molecules appear to interact with each other through the π-stacking (aromatic stacking) process while retaining this hydrogen bond with the kaolinite surface. This is clearly in favor of cluster formation on the clay surface and promotes dimer-type photoproducts.

Effects of Pollution on Pregnancy and Infants.

The fetus is particularly susceptible to environmental contaminants as it is developing at the time of pregnancy and is, therefore, more susceptible to their effects. Pregnancy loss, which includes stillbirth and spontaneous abortion (miscarriage), preterm labor and delivery, and neonatal death, is the worst pregnancy outcome. Stunting and its related health and developmental effects are particularly common in populations living in underdeveloped countries or those exposed to high levels of particle pollution. Several environmental toxins can affect an embryo, fetus, or infant as they are developing. This study explores the following questions: What part do pesticides, heavy metals, dioxin derivatives, and polychlorinated diphenyl compounds play as macroenvironmental pollutants in mutagenesis and teratogenesis? What effects do substances that exposed persons have considerable control over, such as alcohol, narcotics, and tobacco smoke, have on the microenvironment? What consequences should practitioners be aware of these toxins in terms of ethics and the law? This study seeks to assess pertinent primary scientific studies on how pollution affects the health of the fetus and newborn during pregnancy.

A Catalyst-Free Expeditious Green Synthesis of Quinoxaline, Oxazine, Thiazine, and Dioxin Derivatives in Water under Ultrasound Irradiation

Quinoxaline, 1,4-oxazine, 1,4-thiazine and 1,4-dioxin derivatives are important heterocycles gaining considerable attention due to their pharmacological importance and biological activities.1–9 The...

Triphenylantimony(V) Catecholates Based on o-Quinones, Derivatives of Benzo[b][1,4]-Dioxines and Benzo[b][1,4]-Dioxepines

New catecholate complexes of triphenylantimony(V), (Etgly-3,6-DBCat)SbPh3 (I), (Propgly-3,6-DBCat)SbPh3 (II), and (Cat-3,6-DBCat)SbPh3 (III), based on analogs of sterically hindered 3,6-di-tert-butyl-o-benzoquinone, 5,8-di-tert-butyl-2,3-dihydrobenzo[b][1,4]dioxine-6,7-dione (L1), 6,9-di-tert-butyl-2,3-dihydrobenzo[b][1,4]dioxepine-7,8-dione (L2), and 1,4-di-tert-butyl-dibenzo[b,e][1,4]dioxine-2,3-dione (L3), which are the 2,3-dihydrobenzo[b][1,4]dioxine, 2,3-dihydrobenzo[b][1,4]dioxepine, and dibenzo[1,4]dioxine derivatives, respectively, have been synthesized. At room temperature catecholates I and II react with molecular oxygen adding an O2 molecule to form the corresponding spiroendoperoxides IV and V. Catecholate III reacts with oxygen with the deep oxidation of the complex and formation of neutral o-benzoquinone. The molecular structures of complexes I and III are determined by X-ray diffraction analysis (CIF files CCDC nos. 1840299 (I · toluene) and 1840300 (III)).

Enantioselective Access to Chiral 2-Substituted 2,3-Dihydrobenzo[1,4]dioxane Derivatives through Rh-Catalyzed Asymmetric Hydrogenation.

Rh-catalyzed asymmetric hydrogenation of various benzo[ b][1,4]dioxine derivatives was successfully developed to prepare chiral 2-substituted 2,3-dihydrobenzo[1,4]dioxane derivatives using ZhaoPhos and N-methylation of ZhaoPhos ligands with high yields and excellent enantioselectivities (up to 99% yield, >99% enantiomeric excess (ee), turnover number (TON) = 24 000). Moreover, this asymmetric hydrogenation methodology, as the key step with up to 10 000 TON, was successfully applied to develop highly efficient synthetic routes for the construction of some important biologically active molecules, such as MKC-242, WB4101, BSF-190555, and ( R)-doxazosin·HCl.

The relationship between dioxins exposure and risk of prostate cancer with steroid hormone and age in Vietnamese men

Although Vietnam's massive herbicide exposure in 1960s and 1970s was clearly injurious to health, not all causal relationships have been clarified. We therefore explored associations among dioxins, steroid hormones, age and prostate cancer risk in men. We compared serum levels of dioxin, steroid hormones and prostate specific antigen (PSA) in men aged 56–81years from herbicide-exposed hotspots (n=50) with those from non-sprayed regions (n=48). Mean serum levels of dioxin congeners in the hotspot group were 1.5–11.3 times higher than the non-sprayed group depending on specific compound. Levels of testosterone, estradiol and 3β-hydroxysteroid dehydrogenase (3β-HSD) activity in the hotspot group were also significantly higher than in non-sprayed group. Estradiol levels were significantly related to levels of several specific dioxin derivatives in both group. Significant positive correlations were also found between DHT and 1234678-HpCDD or 1234678-HpCDF; and between 3β-HSD activity and 123678-HxCDD, 123478-HxCDF, 123678-HxCDF, or HxCB#169. After adjusting for age, body mass index, and tobacco use, multiple linear regressions showed levels of dihydrotestosterone (DHT), estradiol, testosterone and 3β-HSD activity were not associated with dioxins in the two groups; however, levels of DHT, testosterone and 3β-HSD activity increased significantly with age in the hotspot group. The hotspot and non-sprayed groups did not significantly differ in PSA levels. But six of the hotspot subjects had PSA levels >3ng/mL, 3 of whom were suspected to have prostate cancer (PC) after digital rectal examination. Our findings suggest that dioxin exposure can lead to increased levels of several sex steroid hormones with age. The correlation of dioxin with steroid hormone levels and prostate cancer risk should be studied further.

Ultrasound mediated synthesis of dihydropyrano[3,2-d][1,3]dioxin-7-carbonitrile derivatives in H2O/EtOH medium

Abstract A one-pot cyclocondensation of 1,3-dioxane-5-one (1) with malononitrile and aromatic aldehydes in aqueous sodium hydroxide under ultrasonic irradiation furnishes a series of pyrano[3,2-d][1,3]dioxin derivatives 3. Reactions are completed after a few minutes and the precipitated products are purified by simple crystallization from ethanol. The reaction with ethyl cyanoacetate instead of malononitrile gives the respective analogous products in high yields.

Diagnostic guide enabling distinction between taphonomic stains and enamel hypomineralisation in an archaeological context

ObjectiveMolar Incisor Hypomineralisation (MIH) is a structural anomaly that affects the quality of tooth enamel and has important consequences for oral health. The developmentally hypomineralised enamel has normal thickness and can range in colour from white to yellow or brown with or without surface breakdown. The possibility of finding MIH in ‘ancient populations' could downplay several current aetiological hypotheses (e.g., dioxin derivatives, bisphenols, antibiotics) without excluding the possible multifactorial aspect of the anomaly. In an archaeological context, chemical elements contained in the burial ground can stain teeth yellow or brown and therefore might create a taphonomic bias. The purpose of the present study is to test a proposed diagnostic guide enabling determination of the pathological or taphonomic cause of enamel discolouration and defects that resemble MIH present on ‘ancient teeth'. DesignTwo sample groups including MIH discoloration (n=12 teeth) from living patients, taphonomic discoloration (n=9 teeth) and unknown discoloration (n=2 teeth) from medieval specimens were tested. Three non-destructive methods—Raman spectroscopy, X-ray micro-computed tomography and X-ray fluorescence were utilised. ResultsHypomineralised enamel has decreased mineral density (p<0.0001) and increased phosphate/β-carbonate ratio (p<0.01) compared to normal enamel whereas relative concentrations of manganese, copper, iron and lead are similar. In taphonomic discoloration, relative concentrations of these elements are significantly different (p<0.05) to normal enamel whereas mineral density and Raman spectra profile are comparable. ConclusionsEnamel hypomineralisation can be distinguished from taphonomic staining in archaeological teeth.

Capture of dioxin derivatives on activated carbons: breakthrough curve modelling and isotherm parameters

Four dioxin derivatives (benzene, chlorobenzene, dichlorobenzene and o-chlorophenol) were individually adsorbed onto each of four types of activated carbon (AC) derived from different raw materials. The observed adsorption bed capacities were in the range of 0.916-0.99, with the AC derived from coconut shell (ACC) having the highest bed capacity of 0.99. The micropore size significantly affected the adsorption. The adsorption behaviour evaluation of ACC by thermal gravimetric analysis revealed that the highest activation energy for desorption belonged to o-chlorophenol (107 kJ/mol), followed by dichlorobenzene (102 kJ/mol), chlorobenzene (55 kJ/mol) and benzene (42 kJ/mol). Thus, chemisorption predominated over the interaction between ACC and dioxin derivatives. The ACC was then selected as the absorbent to model the breakthrough curves of the adsorption of the dioxin derivatives using the Aspen gas adsorption simulation program. Langmuir isotherm parameters were determined, and the simulation was found to provide a high adsorption performance compared to the experimental results in all cases.

Capture of dioxin derivatives on activated carbons: breakthrough curve modelling and isotherm parameters

Four dioxin derivatives (benzene, chlorobenzene, dichlorobenzene and o-chlorophenol) were individually adsorbed onto each of four types of activated carbon (AC) derived from different raw materials. The observed adsorption bed capacities were in the range of 0.916-0.99, with the AC derived from coconut shell (ACC) having the highest bed capacity of 0.99. The micropore size significantly affected the adsorption. The adsorption behaviour evaluation of ACC by thermal gravimetric analysis revealed that the highest activation energy for desorption belonged to o-chlorophenol (107 kJ/mol), followed by dichlorobenzene (102 kJ/mol), chlorobenzene (55 kJ/mol) and benzene (42 kJ/mol). Thus, chemisorption predominated over the interaction between ACC and dioxin derivatives. The ACC was then selected as the absorbent to model the breakthrough curves of the adsorption of the dioxin derivatives using the Aspen gas adsorption simulation program. Langmuir isotherm parameters were determined, and the simulation was found to provide a high adsorption performance compared to the experimental results in all cases.

Synthesis and biological evaluation of a series of benzoxazole/benzothiazole-containing 2,3-dihydrobenzo[b][1,4]dioxine derivatives as potential antidepressants

A series of benzoxazole/benzothiazole-2,3-dihydrobenzo[b][1,4]dioxine derivatives (5a–5d and 8a–8j) was synthesized. Compounds were evaluated for binding affinities at the 5-HT1A and 5-HT2A receptors. Antidepressant activities of the compounds were screened using the forced swimming test (FST) and the tail suspension test (TST). The results indicated that the compounds exhibited high affinities for the 5-HT1A and 5-HT2A receptors and showed a marked antidepressant-like activity. Compound 8g exhibited high affinities for the 5-HT1A (Ki=17nM) and 5-HT2A (Ki=0.71nM) receptors; it also produced a decrease of the immobility time and exhibited potent antidepressant-like effects in the FST and TST in mice.

Naphthalene and 2,3-dihydrobenzo[b][1,4]dioxine derivatives with extended side chains as new scaffolds of CB2-selective ligands

Herein, we report the synthesis of naphthalene, dihydrobenzodioxine and fluorene derivatives with extended side chains and their biological evaluation as ligands of CB1 and CB2 receptors.

Synthesis of some di- and trifluoro quinoxaline and dioxine derivatives from pentafluoropyridine

Novel [6,6,6] ring fused tricyclic systems can be readily synthesized in one-pot annulation reaction of pentafluoropyridine or 4-phenylsulfonyl tetrafluoropyridine with appropriate difunctional nitrogen and oxygen nucleophiles attached to aromatic rings. Reaction of 4-phenylsulfonyl tetrafluoropyridine with 2,6-diaminopyridine gave [6,5,6] ring fused systems arising from a tandem SNAr and cyclisation process. From this investigation, di- and trifluorinated quinoxaline and dioxine scaffolds were synthesized.

Three Component Synthesis of Substituted 4H‐[1,3]Dioxin Derivatives Under Solvent‐Free Conditions

Reaction between aryl aldehydes, acetylacetone and alkyl isocyanides in solvent‐free conditions provided a simple and efficient one‐pot route for the synthesis of 1‐(2‐alkylamino‐6‐methyl‐4‐aryl‐4H‐[1,3]dioxin‐5‐yl)ethanone derivatives in excellent yields.

Two new dioxin derivatives from the aerial parts of Lawsonia alba

From the aerial parts of Lawsonia alba two new dioxin derivatives, namely 12-[2′-(1′, 4′-dioxin-5′, 6′-dione)-8″E-undecenyl-dodecanoate (1) and 5-[1′-(docosa-2′E, 5′E-dienyl)]-1,4-dioxin-2,3-dione (2), were isolated and characterised on the basis of spectroscopic methods.

DNA−Cyclodextrin Composite Material for Environmental Applications

Recently, we prepared water-insoluble and nuclease-resistant DNA films by UV irradiation. The DNA films accumulated the harmful DNA-intercalating compounds, such as ethidium bromide and acridine orange. Additionally, the water-insoluble DNA films bound endocrine disruptors that had planar structures, such as dioxin derivatives, polychlorobiphenyl (PCB) derivatives, and benzo[a]pyrene. However, other harmful endocrine disruptors that lack a planar structure, such as bisphenol A and diethylstilbestrol, did not bind the water-insoluble DNA films. Therefore, we prepared the DNA-cyclodextrin composite material by mixing the DNA and the cyclodextrin-immobilized poly(allylamine) (PCD). As a result, these composite materials had properties of both the double-stranded DNA, such as intercalation, and the cyclodextrin, such as encapsulation of an organic molecule into the intramolecular cavity. Therefore, these materials could accumulate not only the harmful compounds with planar structures but also the nonplanar molecules, such as bisphenol A, diethylstilbestrol, and nonylphenol. These DNA-PCD composite materials may have the potential to be novel environmental materials that absorb harmful compounds.

Photochemical behaviour of triclosan in aqueous solutions: Kinetic and analytical studies

The mechanism of the direct photolysis of the anti-microbial triclosan in aqueous solutions was investigated by using steady state and laser flash photolysis. Quantum yields were determined for the disappearance of triclosan and formation of chloride anions in steady state irradiations in the absence and in the presence of oxygen as well as a function of pH. The photoreactivity was found to be efficient with the anionic form and in the absence of oxygen. Following laser flash photolysis (226 nm), three transients were found (triclosan triplet state, solvated electron and phenoxyl radical). Several primary and secondary stable photoproducts were elucidated by means of LC/MS/MS data. They were found to arise from four main photochemical processes: isomerisation, cyclization (leading to the formation of dioxin derivatives), dimerisation of the phenolic moiety and hydrolysis. The ionic chromatography showed that the loss of chloride anion in triclosan phototransformation represents an important degradation pathway. The formation of oligomeric products was also observed for prolonged irradiation time. A detailed mechanism for the formation of the primary products is proposed and discussed. The very important photocyclization reaction is more likely involving the triplet state pathway and the homolytic dissociation of the ether bridge occurs from the singlet excited state pathway.

Synthesis and glycogen phosphorylase inhibitor activity of 2,3-dihydrobenzo[1,4]dioxin derivatives

Novel 5-benzyl and 5-benzylidene-thiazolidine-2,4-diones carrying 2,3-dihydrobenzo[1,4]dioxin pharmacophore were synthesized and their glycogen phosphorylase inhibitor activity was also studied.

Stereospecific Synthesis of Chiral Tetrahydroquinoxaline, 2,3- Dihydrobenzo[ 1,4]dioxin and 2,3-Dihydro-naphtho[2,3-b][1,4]-dioxin Derivatives

In this communication a convenient and novel method for the stereospecific synthesis of chiral tetrahydroquinoxaline, 2,3-dihydro-benzo[1,4]dioxin and 2,3-dihydro-naphtho[2,3-b][1,4]dioxin derivatives from anhydro sugars is described.