Dioxane Derivatives Research Articles

The Impact of Adding Dioxane Derivatives to Polyurethane Structures on their Performance and Degradation in the Environment

The novel dioxane-polyether polyurethanes underwent a 12-month outdoor soil burial test to look into how they would degrade in a natural setting. The structure, thermal properties, surface features, and mechanical strength of the polyurethane films were compared. The initial chemical structure and subsequent chemical alterations were identified using FTIR spectroscopy. The polyurethane samples were less thermally stable throughout the duration of the soil burial test, according to TG/DTG curves. According to all findings, polyurethanes containing 1,3-dioxane-5,5-dimethanol exhibit excellent physical characteristics and mild degradation levels after being buried in soil for a year. These polyether urethanes can break down if the rigid domain structure is exposed to moisture and if microorganisms can spread into the polymer matrix. The physical properties, surface features, and degradation of polyether polyurethanes can be improved by varying the molar ratios of the hard segment components and the dioxane derivative structures.

Low temperature synthesis of bio-fuel additives via valorisation of glycerol with benzaldehyde as well as furfural over a novel sustainable catalyst, 12-tungstosilicic acid anchored to ordered cubic nano-porous MCM-48

The present article demonstrates designing of novel catalyst, 12-tungstosilicic acid (TSA) anchored to ordered nano-porous MCM-48 (nMCM-48); TSA/nMCM-48, characterization and evaluation for synthesis of bio-fuel additives via glycerol valorisation with aromatic aldehydes. The nanopores of support were confirmed by BET and TEM while the interaction between TSA and nMCM-48 was confirmed by decrease in the surface area and pore volume of the catalysts. Assessment of vital reaction parameters (% loading of active species, mole ratio of reactants, catalyst amount, temperature and time) were performed to achieve maximum conversion of glycerol. The catalyst showed noteworthy performance at 30 °C towards conversion (>85 %) and thermodynamically stable dioxane derivative (>60 %) with remarkable TON (5945 for benzaldehyde and 7355 for furfural). The catalyst was regenerated and used for successive four catalytic runs with almost same activity. The superiority of novel catalyst is because of its geometry and nano porosity.

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.

Selective cyclodimerization of epichlorohydrin to dioxane derivatives over MOFs

Glycerol can be converted to valuable products such as epichlorohydrin which is an important intermediate applied in various industries. For example, dioxane derivatives, which are important pharmaceuticals, can be obtained from epichlorohydrin. In the present study, ZIF-8, ZIF-67, MIL-100, and UiO-66 were applied for the direct cyclodimerization of epichlorohydrin. These MOFs were selected because they were already applied asactive catalysts in ring opening of epoxides. Among them, ZIF-8 showed the highest activity and selectivity in the absence of any solvent or co-catalyst. Using ZIF-8asa catalyst, the cyclodimer product (1,4-dioxane 2,5-bis-chloromethyl) was obtained in a yield of about 70% which was significantly superior to previous homo or heterogeneous catalysts for this reaction. Due to ZIF-8 structure and the proposed mechanism, the cyclodimerization reaction catalyzed either by the defects in the structure and/or on the surface. Furthermore, acidic-basic characteristics were also in play. The NH3 and CO2 temperature-programed desorption technique were utilized to identify the active sites and thereby reaction mechanism. Moreover, because of similar properties of ZIF-8 to zeolites, the activity of commercial ZSM-5 for the same reaction was also investigated in this work.

Greener Chemistry for Hybrid Materials, Alcohol‐Free Synthesis with an Epoxy‐Cyclohexyl Precursor

Green synthesis is one of the hot topics in the chemistry of hybrid organic–inorganic materials. A alcohol‐free sol–gel process has been developed to prepare optically transparent hybrid films from an epoxy bearing alkoxide, [2‐(3,4‐epoxy‐cyclohexyl)‐ethyl]‐trimethoxysilane (ECTMS). The synthesis is simple and effective because only two components, ECTMS and an aqueous solution of NaOH, are employed. Infrared spectroscopy has been used to monitor the reactivity of the precursor sol as a function of the aging time. Organic–inorganic hybrid films have been then prepared with the different sols via spin‐coating. The presence of the cyclohexyl ring slows down dramatically both the epoxide opening and the capability of the resulting diols in forming a tricyclic dioxane derivative. The highly basic conditions employed in the synthesis favor the formation of the cyclohexyl rings and cage‐ and ladder‐like silica structures. The hybrid films have shown a high transmittance in the visible range and a thermal stability up to 200 °C. image

Synthesis of crown ethers with the incorporated cobalt bis(dicarbollide) fragment

A series of podands (acyclic analogues of crown ethers) related to 18-crown-6 was obtained by ring-opening reactions of the 1,4-dioxane derivative of nido-carborane [10-O(CH2CH2)2O-7,8-C2B9H11] with 1,2-S,S′- and O,O′-dinucleophiles (1,2-dimercaptoethane, 1,2-dimercaptobenzene, 1,2-dimercapto-ortho-carborane, 1,2-dihydroxy-ortho-carborane). By stepwise ring-opening reactions of the dioxane derivative with sulfur-containing nucleophiles the podand related to 15-crown-5 was prepared as well. The reactions of the obtained podands with CoCl2 result in the macrocyclic ring closure giving the corresponding crown ethers with the incorporated cobalt bis(dicarbollide) fragment K[8,8′-μ-S(OCH2CH2OCH2CH2)2-3,3′-Co(1,2-C2B9H9)2] and K[8,8′-μ-o-C6H4(OCH2CH2OCH2CH2S)2-3,3′-Co(1,2-C2B9H9)2]. The structure of Na[8,8′-μ-o-C6H4(OCH2CH2OCH2CH2S)2-3,3′-Co(1,2-C2B9H9)2] was determined by single crystal X-ray diffraction.

Synthesis of podands with nido-carboranyl groups as a basis for construction of crown ethers with an incorporated metallacarborane moiety

The reactions of the dioxane derivative of 7,8-dicarba-nido-undecaborate anion (nido-carborane), [10-O(CH2CH2)2O-nido-7,8-C2B9H11], with a series of O,O′-dinucleophiles (pyrocatechol, resorcinol, hydroquinone, and ethylene glycol) were studied. The nido-carborane-based podand was obtained, which can be used for assembling of crown ethers with an inserted metallacarborane moiety.

ChemInform Abstract: Prins Cyclization of Styrenes or Acetophenone Catalyzed by DBSA in Water.

AbstractDodecylbenzenesulfonic acid (DBSA) is shown to be an efficient catalyst for the Prins cyclization of styrene derivatives with formaldehyde or acetaldehyde in water to give a variety of aryl‐substituted dioxane derivatives.

Manadoperoxides, a new class of potent antitrypanosomal agents of marine origin

Chemical investigation of the marine sponge Plakortis cfr. lita afforded a library of endoperoxyketal polyketides, manadoperoxides B-K (3-5 and 7-13) and peroxyplakoric esters B(3) (6) and C (14). Eight of these metabolites are new compounds and some contain an unprecedented chlorine-bearing THF-type ring in the side chain. The library of endoperoxide derivatives was evaluated for in vitro activity against Trypanosoma brucei rhodesiense and Leishmania donovani. Some compounds, such as manadoperoxide B, exhibited ultrapotent trypanocidal activity (IC(50) = 3 ng mL(-1)) without cytotoxicity. Detailed examination of the antitrypanosomal activity data and comparison with those available in the literature for related dioxane derivatives enabled us to draw a series of structure-activity relationships. Interestingly, it appears that minor structural changes, such as a shift of the methyl group around the dioxane ring, can dramatically affect the antitrypanosomal activity. This information can be valuable to guide the design of optimized antitrypanosomal agents based on the dioxane scaffold.

GABAA receptors involved in sleep and anaesthesia: β1- versus β3-containing assemblies

The histaminergic neurons of the posterior hypothalamus (tuberomamillary nucleus-TMN) control wakefulness, and their silencing through activation of GABA(A) receptors (GABA(A)R) induces sleep and is thought to mediate sedation under propofol anaesthesia. We have previously shown that the β1 subunit preferring fragrant dioxane derivatives (FDD) are highly potent modulators of GABA(A)R in TMN neurons. In recombinant receptors containing the β3N265M subunit, FDD action is abolished and GABA potency is reduced. Using rat, wild-type and β3N265M mice, FDD and propofol, we explored the relative contributions of β1- and β3-containing GABA(A)R to synaptic transmission from the GABAergic sleep-on ventrolateral preoptic area neurons to TMN. In β3N265M mice, GABA potency remained unchanged in TMN neurons, but it was decreased in cultured posterior hypothalamic neurons with impaired modulation of GABA(A)R by propofol. Spontaneous and evoked GABAergic synaptic currents (IPSC) showed β1-type pharmacology, with the same effects achieved by 3μM propofol and 10μM PI24513. Propofol and the FDD PI24513 suppressed neuronal firing in the majority of neurons at 5 and 100μM, and in all cells at 10 and 250μM, respectively. FDD given systemically in mice induced sedation but not anaesthesia. Propofol-induced currents were abolished (1-6μM) or significantly reduced (12μM) in β3N265M mice, whereas gating and modulation of GABA(A)R by PI24513 as well as modulation by propofol were unchanged. In conclusion, β1-containing (FDD-sensitive) GABA(A)R represent the major receptor pool in TMN neurons responding to GABA, while β3-containing (FDD-insensitive) receptors are gated by low micromolar doses of propofol. Thus, sleep and anaesthesia depend on different GABA(A)R types.

Fragrant Dioxane Derivatives Identify β1-Subunit-containing GABAA Receptors

Nineteen GABA(A) receptor (GABA(A)R) subunits are known in mammals with only a restricted number of functionally identified native combinations. The physiological role of beta1-subunit-containing GABA(A)Rs is unknown. Here we report the discovery of a new structural class of GABA(A)R positive modulators with unique beta1-subunit selectivity: fragrant dioxane derivatives (FDD). At heterologously expressed alpha1betaxgamma2L (x-for 1,2,3) GABA(A)R FDD were 6 times more potent at beta1- versus beta2- and beta3-containing receptors. Serine at position 265 was essential for the high sensitivity of the beta1-subunit to FDD and the beta1N286W mutation nearly abolished modulation; vice versa the mutation beta3N265S shifted FDD sensitivity toward the beta1-type. In posterior hypothalamic neurons controlling wakefulness GABA-mediated whole-cell responses and GABAergic synaptic currents were highly sensitive to FDD, in contrast to beta1-negative cerebellar Purkinje neurons. Immunostaining for the beta1-subunit and the potency of FDD to modulate GABA responses in cultured hypothalamic neurons was drastically diminished by beta1-siRNA treatment. In conclusion, with the help of FDDs we reveal a functional expression of beta1-containing GABA(A)Rs in the hypothalamus, offering a new tool for studies on the functional diversity of native GABA(A)Rs.

Exploring Epidermal Growth Factor Receptor (EGFR) Inhibitor Features: The Role of Fused Dioxygenated Rings on the Quinazoline Scaffold

A number of dioxolane, dioxane, and dioxepine quinazoline derivatives have been synthetized and evaluated as EGFR inhibitors. Their cytotoxic activity has been tested against two cell lines overexpressing and not expressing EGFR. Most derivatives were able to counteract EGF-induced EGFR phosphorylation, and their potency was comparable to the reference compound PD153035. The size of the fused dioxygenated ring was crucial for the biological activity, the dioxane derivatives being the most promising class of this series.

Dodecaborate cluster lipids with variable headgroups for boron neutron capture therapy: Synthesis, physical–chemical properties and toxicity

We have prepared two new boron-containing lipids with potential use in boron neutron capture therapy of tumors. These lipids consist of a diethanolamine frame with two myristoyl chains bonded as esters, and a butylene or ethyleneoxyethylene unit linking the doubly negatively charged dodecaborate cluster to the amino function of the frame, obtained by nucleophilic attack of the amino on the tetrahydrofurane and dioxane derivatives, respectively, of closo-dodecaborate. The latter cluster lipid can form liposomes at 25 °C whereas the former lipid at this temperature assembles into bilayer disks. Both lipids form stable liposomes when mixed with suitable helper lipids. The thermotropic behavior was found to be different for the two lipids, with the butylene lipid showing sharp melting transitions at surprisingly high temperatures. Toxicity in vitro and in vivo varies greatly, with the butylene derivative being more toxic than the ethyleneoxyethylene derivative.

Free‐radical polymerization of dioxolane and dioxane derivatives: Effect of fluorine substituents on the ring opening polymerization

AbstractPartially fluorinated and perfluorinated dioxolane and dioxane derivatives have been prepared to investigate the effect of fluorine substituents on their free‐radical polymerization products. The partially fluorinated monomer 2‐difluoromethylene‐1,3‐dioxolane (I) was readily polymerized with free‐radical initiators azobisisobutyronitrile or tri(n‐butyl)borane–air and yielded a vinyl addition product. However, the hydrocarbon analogue, 2‐methylene‐1,3‐dioxolane (II), produced as much as 50% ring opening product at 60 °C by free‐radical polymerization. 2‐Difluoromethylene‐4‐methyl‐1,3‐dioxolane (III) was synthesized and its free‐radical polymerization yielded ring opening products: 28% at 60 °C, decreasing to 7 and 4% at 0 °C and −78 °C, respectively. All the fluorine‐substituted, perfluoro‐2‐methylene‐4‐methyl‐1,3‐dioxolane (IV) produced only a vinyl addition product with perfluorobenzoylperoxide as an initiator. The six‐membered ring monomer, 2‐methylene‐1,3‐dioxane (V), caused more than 50% ring opening during free‐radical polymerization. However, the partially fluorinated analogue, 2‐difluoromethylene‐1,3‐dioxane (VI), produced only 22% ring opening product with free‐radical polymerization and the perfluorinated compound, perfluoro‐2‐methylene‐1,3‐dioxane (VII), yielded only the vinyl addition polymer. The ring opening reaction and the vinyl addition steps during the free‐radical polymerization of these monomers are competitive reactions. We discuss the reaction mechanism of the ring opening and vinyl addition polymerizations of these partially fluorinated and perfluorinated dioxolane and dioxane derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5180–5188, 2004

ChemInform Abstract: Antifungal Sordarins. Synthesis and Structure—Activity Relationships of 3′,4′‐Fused Dioxolane and Dioxane Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Antifungal sordarins. Synthesis and structure–activity relationships of 3′,4′-Fused dioxolane and dioxane derivatives

A number of novel 3′,4′-fused dioxolane and dioxane sordarin derivatives were synthesised for structure–activity relationship studies. Many of these derivatives exhibit high activity against Candida spp. and Cryptococcus neoformans.

Isomerization and Dimerization Reactions of Methyloxirane over Various Types of Zeolite and Zeotype

The ring-opening reactions of methyloxirane on various zeolites and zeotypes (HZSM-5, CuZSM-5, HY, AlMCM-41, SiMCM-41, and BMCM-41) were investigated at 363 K either in a pulse reactor or in a circulation system, in the presence of hydrogen or nitrogen. The acidic molecular sieves were found to be active in isomerization (the products are propionaldehyde and acetone) and dimerization (the products are dioxolane and dioxane derivatives) reactions. Deoxygenation was of minor importance in hydrogen or nitrogen atmosphere. The major product formation pathway was dimerization on every catalytically active material. This transformation route was favored by the confined environment.

Effects of Substituents on the Ring-Opening Pathways of Oxiranes on ZSM-5 Zeolites

The ring-opening reactions of methyloxirane and ethyloxirane on ZSM-5 catalysts are dramatically different in spite of otherwise identical reaction conditions. Even though both reactants undergo single ring opening providing isomers of the starting compound, the major transformation route of methyloxirane is dimerization resulting in dioxolane and dioxane derivatives of various kinds. This reaction pathway, however, is completely lacking in the case of ethyloxirane. Molecular modeling revealed that possible dimers of ethyloxirane are too bulky to be formed and diffuse through the channel system of the ZSM-5 structure.

Ring-Opening and Dimerization Reactions of Methyl- and Dimethyloxiranes on HZSM-5 and CuZSM-5 Zeolites

Ring-opening and dimerization reactions of methyloxirane and cis- and trans-2,3-dimethyloxirane were studied on CuZSM-5, prepared by various methods, and HZSM-5 zeolites in a closed static recirculation reactor at 363 K in reductive atmosphere. On these materials two main reaction types, ring-opening and dimerization, could be observed. For methyloxirane the major transformation pathways were ring opening and dimerization, producing various dioxolane and dioxane derivatives. In addition to these routes 2,3-dimethyloxiranes underwent deoxygenation and rearrangement as well. The activities and selectivities of the transformations toward these pathways were found to be significantly different depending on the stereochemistry of the substrates as well as the nature of the catalysts. Suggestions for the active sites and transformation mechanisms are also offered.

Two dioxane derivatives of anthraquinone

The structures of 1-methoxy-4-(2-methylprop-2-enyloxy)-2-[(2R,6R)-4,4,6-trimethyl-1,3-dioxan-2-yl]anthraquinone, C 26 H 28 O 6 , and 4-hydroxy-3-(2-methylprop-2-enyl)-2-[(2R,6R)-4,4,6-trimethyl-1,3-dioxan-2-yl]anthraquinone, C 25 H 26 O 5 , have been determined to compare their conformations with those determined for solutions by 1 H NOESY (nuclear Overhauser effect spectroscopy) spectra.