Heating In Dimethyl Sulfoxide Research Articles

Catalyst-Free Cascade Annulation of Enaminones and Aryl Diazonium Tetrafluoroboronates for Cinnoline Synthesis and the Anti-Inflammatory Activity Study.

A simple and concise method for the synthesis of cinnolines has been developed by the reactions of readily available enaminones and aryl diazonium tetrafluoroboronates. The reactions run efficiently to provide cinnolines with broad diversity in the substructure by heating in dimethyl sulfoxide without using any catalyst or additive. In addition, the primary investigation of the anti-inflammatory activity of these products leads to the observation of p-chlorobenzoyl (3f) and p-nitrobenzoyl (3j) cinnolines as attractive anti-inflammatory compounds in vitro.

Recycling of multilayer packaging using a reversible cross‐linking adhesive

AbstractPlastic‐based multilayer packaging has an important function on the packaging market, but is currently not recyclable as the polymer layers used are usually thermodynamically immiscible. This work therefore follows the approach to prepare separable multilayer packaging using a packaging adhesive modified with thermally unstable adducts, and proposes a corresponding recycling process. For this purpose, typical multilayer structures (polyethylene (PE)// polyethylene terephtalate (PET), PET//aluminum, and PE//aluminum) were prepared by curing furan‐/maleimide‐functionalized polyurethane (PU)‐prepolymers with a three‐functional cross‐linking agent. Adhesions of up to over 3N per 15 mm test specimen were measured or substrate failures of PET films were observed. However, heating in dimethylsulfoxide, the retro‐Diels–Alder reaction takes place and the cross‐linked adhesive turns thermoplastic and dissolves in the solvent. Thus, the laminate separates and the pure PE, PET, and aluminum foils can be recovered without any PU residue.

4-[(3,5-Dimethyl-1H-pyrazol-1-yl)methyl]-4-methyl-2-phenyl-4,5-dihydrooxazole

The compound, 4-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-4-methyl-2-phenyl-4,5-dihydrooxazole 2 was prepared in high yield, through nucleophilic substitution reaction of the O-tosyl oxazoline derivative 1, by heating in dimethyl sulfoxide (DMSO) and in presence of KOH as base. The structure of the synthesized compound was established on the basis of NMR spectroscopy (1H, 13C), MS data and elemental analysis.

Phosphenium Hydride Reduction of [(cod)MX2] (M = Pd, Pt; X = Cl, Br): Snapshots on the Way to Phosphenium Metal(0) Halides and Synthesis of Metal Nanoparticles

The outcome of the reduction of [(cod)PtX2] (X = Cl, Br; cod = 1,5-cyclooctadiene) with N-heterocyclic phosphenium hydrides RNHP-H depends strongly on the steric demand of the N-aryl group R and the nature of X. Reaction of [(cod)PtCl2] with DippNHP-H featuring bulky N-Dipp groups produced an unprecedented monomeric phosphenium metal(0) halide [(DippNHP)(DippNHP-H)PtCl] stabilized by a single phosphine ligand. The phosphenium unit exhibits a pyramidal coordination geometry at the phosphorus atom and may according to DFT calculations be classified as a Z-type ligand. In contrast, reaction of [(cod)PtBr2] with the sterically less protected MesNHP-H afforded a mixture of donor-ligand free oligonuclear complexes [{(MesNHP)PtBr}n] (n = 2, 3), which are structural analogues of known palladium complexes with μ2-bridging phosphenium units. All reductions studied proceed via spectroscopically detectable intermediates, several of which could be unambiguously identified by means of multinuclear (1H, 31P, 195Pt) NMR spectroscopy and computational studies. The experimental findings reveal that the phosphenium hydrides in these multistep processes adopt a dual function as ligands and hydride transfer reagents. The preference for the observed intricate pathways over seemingly simpler ligand exchange processes is presumably due to kinetic reasons. The attempt to exchange the bulky phosphine ligand in [(DippNHP)(DippNHP-H)PtCl] by Me3P resulted in an unexpected isomerization to a platinum(0) chlorophosphine complex via a formal chloride migration from platinum to phosphorus, which accentuates the electrophilic nature of the phosphenium ligand. Phosphenium metal(0) halides of platinum further show a surprising thermal stability, whereas the palladium complexes easily disintegrate upon gentle heating in dimethyl sulfoxide to yield metal nanoparticles, which were characterized by TEM and XRD studies.

Temperature-Triggered Switchable Helix-Helix Inversion of Poly(phenylacetylene) Bearing l-Valine Ethyl Ester Pendants and Its Chiral Recognition Ability.

A phenylacetylene containing the l-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh4) to produce the corresponding one-handed helical cis-poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not observed in highly polar solvents, such as N,N′-dimethylformamide (DMF). By heating the solution of PPAA-Val in chloroform, the sign of the CD absorption became reversed, but recovered after cooling the solution to room temperature. Even after six cycles of the heating-cooling treatment, the helix sense of the PPAA-Val’s backbone was still switchable without loss of the CD intensity. The PPAA-Val was then coated on silica gel particles to produce novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). These novel PPAA-Val based CSPs showed a high chiral recognition ability for racemic mandelonitrile (α = 2.18) and racemic trans-N,N′-diphenylcyclohexane-1,2-dicarboxamide (α = 2.60). Additionally, the one-handed helical cis-polyene backbone of PPAA-Val was irreversibly destroyed to afford PPAA-Val-H by heating in dimethyl sulfoxide (DMSO) accompanied by the complete disappearance of the Cotton effect. Although PPAA-Val-H had the same l-valine ethyl ester pendants as its cis-isomer PPAA-Val, it showed no chiral recognition. It was concluded that the one-handed helical cis-polyene backbone of PPAA-Val plays an important role in the chiral recognition ability.

Polysaccharides of algae 68. Sulfated polysaccharides from the Kamchatka brown alga Laminaria bongardiana

Several fucoidan fractions were isolated from the biomass of the Kamchatka brown alga Laminaria bongardiana by hot water extraction followed by anion-exchange chromatography. Fucoidans were found to be composed of l-fucose, d-galactose, and sulfate as the major components, whereas d-xylose, d-mannose, d-glucuronic acid, and acetate were detected as the minor constituents. Highly sulfated fucoidan fractions F-2 and F-3 were solvolytically desulfated by heating in dimethyl sulfoxide in the presence of pyridine. The structures of native and desulfated polysaccharides were investigated by the methylation analysis and NMR spectroscopy. It was shown that F-2 contains fucan sulfate, the backbone of which is made of 1→3-linked α-l-fucopyranose residues with single α-l-Fucp branches at positions 2 and sulfate groups predominantly at positions 4. Sulfated fucoglucuronomannan, fucoglucuronan, and fucogalactan were detected in F-2 as concomitant polysaccharides. Fucan sulfate and sulfated fucogalactan were the major components of the fraction F-3. The anticoagulant properties of fucoidan fractions were assessed. It was demonstrated that the activity of the fraction F-3 is comparable with that of low-molecular-weight heparin (enoxaparin), whereas the activity of total fucoidan F and the fraction F-2 is ~2/3 and ~1/2, respectively, of the activity of F-3, which is in accordance with the lower sulfate content in these samples. Desulfated preparations F-2deS and F-3deS were completely devoid of anticoagulant activity.

A twisted-intramolecular-charge-transfer (TICT) based ratiometric fluorescent thermometer with a mega-Stokes shift and a positive temperature coefficient.

The fluorescence intensity of N,N-dimethyl-4-((2-methylquinolin-6-yl)ethynyl)aniline exhibits an unusual intensification with increasing temperature, by activating more vibrational bands and leading to stronger TICT emissions upon heating in dimethyl sulfoxide. Based on the different temperature dependence at various wavelengths, as shown in the TICT fluorescence spectrum, this dye can be employed to ratiometrically detect temperature.

ChemInform Abstract: Diprotodecarboxylation Reactions of 3,4‐Dialkoxythiophene‐2,5‐dicarboxylic Acids Mediated by Ag2CO3 and Microwaves.

Abstract An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag2CO3/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag2CO3/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Triazidation of 2,4,6-trifluorobenzenes

1,3,5-Trichloro-2,4,6-trifluorobenzene and 1-bromo-3,5-dichloro-2,4,6-trifluorobenzene undergo selective defluorination on heating in dimethylsulfoxide with sodium azide to form 1,3,5-triazido-2,4,6-trichlorobenzene and 1,3,5-triazido-2-bromo-4,6-dichlorobenzene in high yields. The azidation of 1,3,5-tribromo-2,4,6-trifluorobenzene under similar reaction conditions leads to the mixture of 1,3-diazido-2,4,6-tribromo-5-fluorobenzne and 1,3,5-triazido-2,4,6-tribromobenzene in the 1:2 ratio, respectively. 1,3,5-Triazido-2,4,6-tribromobenzene can be obtained as a sole product in high yield if the azidation of 1,3,5-tribromo-2,4,6-trifluorobenzene with sodium azide is carried out in aqueous acetone. The triazides obtained are the first readily available 1,3,5-triazidobenzenes that may find a wide practical use as new photoactive cross-linking reagents for polymer chemistry and as starting compounds in organic synthesis and photochemical preparation of new organic magnetic materials.

Synthesis and molecular structure of the novel bismuth(III) sulfonate complex [Bi(C18H14P(O)SO3)2(DMSO)3](NO3)∙DMSO∙2H2O

The synthesis of [Bi(C18H14P(O)SO3)2(DMSO)3](NO3)∙DMSO∙2H2O starting from [Bi6O4(OH)4](NO3)6∙H2O and 2-(diphenylphosphino)benzenesulfonic acid is presented. 31P{1H}-NMR experiments confirm the in situ oxidation of 2-(diphenylphosphino)benzenesulfonic acid to give 2-(diphenylphosphine oxide)benzenesulfonic acid by heating in dimethyl sulfoxide (DMSO). In the presence of [Bi6O4(OH)4](NO3)6∙H2O, subsequent formation of single crystals of the title compound is observed. The crystal structure determination reveals that the bismuth atom shows a [5+4] coordination with short Bi–O distances in the range of 2.278(11) to 2.398(11) Å to the oxygen atoms of DMSO and phosphine oxide groups and with longer Bi–O bonds of 2.74(2) and 2.88(2) Å to the chelating sulfonate groups.

Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing tetraoxyethylene units exhibiting amphotropic liquid‐crystalline and photoluminescence properties

AbstractSeveral poly(pyridinium salt)s containing various organic counterions and tetraoxyethylene units in their backbones were synthesized by either ring‐transmutation polymerization reaction of 4,4'‐(1,4‐phenylene)bis(2,6‐diphenylpyrylium tosylate) with bis(2‐(2‐(4‐aminophenoxy)ethoxy)ethyl) ether on heating in dimethyl sulfoxide or metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H‐NMR and 13C‐NMR spectroscopy, and elemental analyses. Their number‐average molecular weights and polydispersity indices were in the range of 34,000–52,000 and 1.14–1.38, respectively, as determined by gel permeation chromatography. They were characterized both for their thermotropic and lyotropic liquid‐crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. As these polymers exhibited liquid‐crystalline phase both in the melt and in solutions, they are classified as an amphotropic class of ionic polymers. Their light‐emitting properties in a large number of organic solvents that ranged from nonpolar to polar solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing oxyethylene unit exhibiting amphotropic liquid-crystalline and photoluminescence properties

Several poly(pyridinium salt)s containing various organic counterions and oxyethylene unit in their backbones were synthesized by either the ring-transmutation polymerization reaction of 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,2-bis(4-aminophenoxy)ethane on heating in dimethyl sulfoxide or the metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H and 13C NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 59,000–63,000 and 1.41–1.65, respectively, as determined by gel permeation chromatography. They were characterized for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. Since these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they belong to an amphotropic class of ionic polymers. Their light-emitting properties both in polar organic solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry.

Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine: synthesis of novel R F-containing isoxazole and chromone derivatives

Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine free base proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4 H-chromeno[3,4- d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones, which were successfully hydrolyzed with concentrated H 2SO 4 to afford 3-carbamoyl-2-(polyfluoroalkyl)chromones. On the other hand, oximation of 3-(polyfluoroacyl)chromones with hydroxylamine hydrochloride occurs either at the carbonyl carbon atom connected to the R F group or at the C-2 atom to give 3-R FC( NOH)-chromones and 5-R F-4-salicyloylisoxazole oximes, respectively. The former were easily converted to 3-R F-4-salicyloylisoxazoles by simple heating in dimethyl sulfoxide.

Ring transformations of aziridinyl 2-phosphonates: synthesis of 5-phosphono-2-oxazolidinones and 5-phosphono-2-imidazolidinones

Syntheses of 5-phosphono-2-oxazolidinones and 5-phosphono-2-imidazolidinones were achieved from the corresponding 1-vinyl-2-phosphonoaziridines. Regioselective aziridine ring opening employing methyl chloroformate affords 1-amido-2-chloroethylphosphonates, which were easily transformed into the corresponding 2-oxazolidinones upon heating in dimethyl sulfoxide. Treatment of the aziridine ring opening products with ammonia furnishes vinylphosphonates, which undergo a Michael type addition with several amines. In situ ring closure of the addition products yields the corresponding phosphonylated 2-imidazolidinones.

Structures, Photoluminescence, and Reversible Vapoluminescence Properties of Neutral Platinum(II) Complexes Containing Extended π-Conjugated Cyclometalated Ligands

Reacting K2PtCl4 with the tridentate R-C(wedge)N(wedge)C-H2 ligands 2,6-di-(2'-naphthyl)-4-R-pyridine (R = H, 1a; Ph, 1b; 4-BrC6H4, 1c; 3,5-F2C6H3, 1d) in glacial acetic acid, followed by heating in dimethyl sulfoxide (DMSO), gave complexes [(R-C(wedge)N(wedge)C)Pt(DMSO)] (2a-d). In the crystal structures of 2a-c, the molecules are paired in a head-to-tail orientation with Pt...Pt separations >6.3 A, and there are extensive close C-H...pi (d = 2.656-2.891 A), pi...pi (d = 3.322-3.399 A), and C-H...O=S (d = 2.265-2.643 A) contacts. [(Ph-C(wedge)N(wedge)C)Pt(PPh3)] (3) was prepared by reacting 2b with PPh3. Reactions of 2a-d with bis(diphenylphosphino)methane (dppm) gave [(R-C(wedge)N(wedge)C)2Pt2(mu-dppm)] (4a-d). Both head-to-head (syn) and head-to-tail (anti) conformations were found for 4a.6CHCl3.C5H12, whereas only one conformation was observed for 4b.2CHCl3 (syn), 4c.3CH2Cl2 (syn), and 4d.2CHCl3 (anti). In the crystal structures of 4a-d, there are close intramolecular Pt...Pt contacts of 3.272-3.441 A in the syn conformers, and long intramolecular Pt...Pt separations of 5.681-5.714 A in the anti conformers. There are weak C-H...X (d = 2.497-3.134 A) and X...X (X = Cl or Br; d = 2.973-3.655 A) interactions between molecules 4a-d and occluded CHCl3/CH2Cl2 molecules, and their solvent channels are of varying diameters (approximately 9-28 A). Complexes 2a-d, 3, and 4a-d are photoluminescent in the solid state, with emission maxima at 602-643 nm. Upon exposure to volatile organic compounds, 4a shows a fast and reversible vapoluminescent response, which is most intense with volatile halogenated solvents (except CCl4). Powder X-ray diffraction analysis of desolvated 4a revealed a more condensed molecular packing of syn and anti complexes than crystal 4a.6CHCl3.C5H12.

Synthesis and Characterization of Poly(pyridinium salt)s with Organic Counterions Exhibiting Both Thermotropic Liquid-Crystalline and Light-Emitting Properties

Two poly(pyridinium salt)s with bulky organic counterions (tosylate and triflimide) were synthesized by either the ring-transmutation polymerization reaction of 4,4‘-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,12-diaminododecane on heating in dimethyl sulfoxide (DMSO) at 145−150 °C for 24 h or the metathesis reaction of the corresponding tosylate polymer with lithium triflimide in a common organic solvent such as acetonitrile. Their polyelectrolyte behavior in DMSO was determined by solution viscosity measurements, and their chemical structures were determined by Fourier transform infrared and Fourier transform NMR spectroscopy. They were characterized for their thermotropic liquid-crystalline properties with a number of experimental techniques. Poly(pyridinium salt) with tosylate as a counterion had a crystal-to-smectic phase transition at 116 °C that persisted up to its decomposition temperature. The corresponding polymer with triflimide as a counterion had not only lower crystal-to-smectic phase transition at 80 °C but also a smectic-to-isotropic transition at about 180 °C. Both of these transitions were well below its decomposition temperature. It had better thermal stability than that of the corresponding tosylate polymer. Their fluorescence property in solutions of tetrahydrofuran and methanol as well as in the solid state was also included in this study.

Synthesis and Cascade Rearrangement of 3‐Arylazo‐4‐(3‐ethoxycarbonylureido)furoxans.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and cascade rearrangement of 3-arylazo-4- (3-ethoxycarbonylureido)furoxans

3-Arylazo-4-(3-ethoxycarbonylureido)furoxans, which were synthesized by the reactions of 4-amino-3-arylazofuroxans with ethoxycarbonyl isocyanate, were subjected to cascade rearrangements under the action of potassium tert-butoxide in dimethylformamide or by heating in dimethyl sulfoxide to form 4-amino-2-aryl-5-nitro-2H-1,2,3-triazoles. X-ray diffraction study and quantum-chemical calculations (B3LYP/6-31G**) of one of ureidofuroxans demonstrated that the intramolecular contact between the carbonyl group and the nitrogen atom of furoxan corresponds to the charge transfer from the lone electron pair of the oxygen atom to the antibonding orbital of the N—O bond.

Synthesis and characterization of poly(pyridinium salt)s with organic counterion exhibiting both lyotropic liquid-crystalline and light-emitting properties

Two poly(pyridinium salt)s containing a bulky organic counterion such as 2-naphthalenesulfonate were synthesized by the ring-transmutation polymerization reaction of bis(pyrylium 2-naphthalenesulfonate) with the corresponding aromatic diamines on heating in dimethyl sulfoxide (DMSO) at 145–150 °C for 24 h, and characterized for their lyotropic liquid crystalline as well as fluorescence properties in both polar protic and aprotic solvents such as methanol and DMSO. Their polyelectrolyte behavior in DMSO was also determined by solution viscosity measurements.