Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SULFONES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2002

Versatile "traceless" sulfone linker for SPOS: preparation of isoxazolinopyrrole 2-carboxylates.

A five-step solid-phase synthesis of isoxazolinopyrrole-2-carboxylates (6) that employs a traceless sulfone linker strategy is reported. Resin-bound diene 4, obtained by acetylation and concomitant beta-elimination of acetate from resin-bound allylic alcohol 3, underwent regioselective 1,3-dipolar cycloadditons with nitrile oxides. Formation of the pyrrole products in a resin-releasing strategy was performed by pyrrole annulation with alkyl isocyanoacetates, which react with the vinyl sulfone moiety to generate the target isoxazolinopyrrole-2-carboxylates (6). Use of this chemistry afforded eight isoxazolinopyrrole-2-carboxylates in 6-24% overall yields from polystyrene/divinylbenzene sulfinate 1.

Journal Article↗
PubMed2002

Cycloheptyne intermediate in the reaction of chiral cyclohexylidenemethyliodonium salt with sulfonates.

Reactions of (R)-4-methylcyclohexylidenemethyl(phenyl)iodonium salt and its 3-trifluoromethylphenyl and 4-methoxyphenyl derivatives (1) with tetrabutylammonium mesylate and triflate were carried out in chloroform at 60 degrees C. The products include (S)-4-methylcyclohexylidenemethyl sulfonate (2) and (R)-5-methylcyclohept-1-enyl sulfonate (3) as well as iodoarene. Reactions of (S)-1 were confirmed to provide the counterpart results. The rearranged triflate (R)-3Tf formed in the reaction with triflate maintains mostly the ee (enantiomeric excess) of (R)-1, while the ee of the mesylate product 3Ms is largely lost. The (13)C-labeling at the exocyclic position of 1 results in the isotopic scrambling of C-1 and C-2 of 3Ms in the mesylate reaction. The degree of the scrambling agrees well with that of the loss of ee of (R)-3Ms obtained from (R)-1, implying that the racemization is not due to the intermediate formation of achiral, primary 4-methylcyclohexylidenemethyl cation. Reaction of 1 with mesylate in the presence of CH(3)OD provided the 3Ms deuterated at the 2-position. When tetraphenylcyclopentadienone was added to the mesylate reaction system, the adduct of the 4-methylcycloheptyne intermediate was obtained in 24% yield, but the normal products 2Ms and 3Ms were still formed. The 3Ms obtained here in a low yield maintains the high ee of 1. These results indicate that the cycloheptyne is an intermediate responsible for the formation of racemic product 3Ms in the mesylate reaction. It is also concluded that the unrearranged products 2 are formed via the competitive pathways of in-plane and out-of-plane S(N)2 reactions.

Journal Article↗
PubMed2002

Reaction of allylzinc reagents and zinc enolates of ketones with alpha-amidoalkylphenyl sulfones.

Alpha-amidoalkylphenyl sulfones behave as N-acylimino equivalents in the reaction with functionalized allylzinc reagents. The addition products obtained using the zinc derivative of ethyl 2-(bromomethyl)acrylate can be readily transformed into alpha-methylene-gamma-lactams using different cyclization procedures. The allylzinc reagent obtained from 3-bromo-1-acetoxy-1-propene directly affords protected 1,2-amino alcohols with a preference for the anti stereoisomer, regardless of the structure of the alpha-amidoalkylphenyl sulfone employed. This procedure can be extended to the use of zinc enolates obtained from alpha-bromo ketones and leads to the synthesis of N-protected beta-amino ketones.

Journal Article↗
PubMed2003

Enantiodivergent, catalytic asymmetric synthesis of gamma-amino vinyl sulfones.

A set of diversely substituted N-Boc-gamma-amino vinyl sulfones has been prepared by a four-step procedure from readily available, highly enantiopure anti-N-Boc-3-amino-1,2-alkanediols. This new route, which does not depend on the accessibility of alpha-amino acids as starting materials, is noteworthy for its efficiency, for its generality, and for the fact that both enantiomers of a given gamma-amino vinyl sulfone can be obtained with equal ease.

Journal Article↗
PubMed2003

Preparation of tri- and difluoromethylsilanes via an unusual magnesium metal-mediated reductive tri- and difluoromethylation of chlorosilanes using tri- and difluoromethyl sulfides, sulfoxides, and sulfones.

A new and efficient method for the preparation of tri- and difluoromethylsilanes using magnesium metal-mediated reductive tri- and difluoromethylation of chlorosilanes is reported using tri- and difluoromethyl sulfides, sulfoxides, and sulfones. The byproduct of the process is diphenyl disulfide. Since phenyl trifluoromethyl sulfone, sulfoxide, and sulfide are readily prepared from trifluoromethane (CF(3)H) and diphenyl disulfide, the method can be considered to be catalytic in diphenyl disulfide for the preparation of (trifluoromethyl)trimethylsilane (TMS-CF(3)) from non-ozone-depleting trifluoromethane.

Journal Article↗
PubMed2004

Calorimetric and computational study of 1,3-dithiacyclohexane 1,1-dioxide (1,3-dithiane sulfone).

The enthalpies of combustion and sublimation of 1,3-dithiacyclohexane 1,1-dioxide (1,3-dithiane sulfone) were measured by a rotating-bomb combustion calorimeter and the Knudsen effusion technique, and the gas-phase enthalpy of formation was determined, Delta(f)H(m)*(g) = -326.3 +/- 2.0 kJ mol(-1). Standard ab initio molecular orbital calculations at the G2(MP2) level were performed, and a theoretical study on molecular and electronic structure of the compound has been carried out. Calculated Delta(f)H(m)*(g) values agree very well with the experimental one. These experimental and theoretical studies support the relevance of the repulsive electrostatic interaction between sulfur atoms in 1,3-dithiane sulfone, that apparently counterbalances any n(S) --> rho(C-SO2)* stabilizing hyperconjugative interaction.

Journal Article↗
PubMed2003

Synthesis, molecular structure, and applications of 2-hydroxylamino-4,5-dihydroimidazolium-O-sulfonate to the synthesis of novel heterocyclic ring systems.

2-hydroxylamino-4,5-dihydroimidazolium-O-sulfonate (1) has been prepared by reacting 2-chloro-4,5-dihydroimidazole with hydroxylamine-O-sulfonic acid. Deprotonated compound 1a containing both the nucleophilic endocyclic nitrogen atoms and electrophilic exocyclic nitrogen was used for the syntheses of 3-substituted 6,7-dihydro-5H-imidazo[2,1-c][1,2,4]oxadiazoles 2-9 and 6,7-dihydro-5H-imidazo[2,1-c][1,2,4]thiadiazole-3-thione (10) by tandem nucleophilic addition-electrophilic amination reaction. The method promises utility in the synthesis of a variety of other heterocycles. On the other hand, the convenient routes to 7,8-dihydroimidazo[1,2-c][1,3,5]thiadiazine-2,4(6H)-dithione (16) and 2,6,7,8-tetrahydroimidazo[1,2-a][1,3,5]triazine-4(3H)-thione derivative (17) are reported starting from compound 1. The structures of the compounds prepared were established by elemental analyses, IR, NMR, and MS spectra, and in some instances X-ray analyses.

Journal Article↗
PubMed2005

Sequential intermediates in the base-catalyzed conversion of bis(pi-conjugated propargyl) sulfones to 1,3-dihydrobenzo- and naphtho[c]thiophene-2,2-dioxides.

[reaction: see text] In a recent article, we reported on the base-catalyzed rearrangements of dipropargyl selenides, -sulfides, -sulfoxides, and -sulfones that eventually lead to polycyclic aromatic products. In the present work, we report on the first isolation and characterization of the thiophene dioxide intermediates 5b,c from a mild tandem isomerization/cyclization/aromatization of bis(pi-conjugated propargyl) sulfones. Monoallene 2b,c and diallene 3b intermediates were also identified by NMR. A kinetic study of the rearrangement of 1a-c revealed that the unusual facile tandem process is highly dependent on the nature of gamma-substitution.

Journal Article↗
PubMed2006

Ruthenium-catalyzed [2+2] cycloadditions of alkynyl sulfides and alkynyl sulfones.

Ruthenium-catalyzed [2+2] cycloadditions of bicyclic alkenes with alkynyl sulfides and alkynyl sulfones were investigated. The sulfide and sulfone moieties were found to be compatible with the Ru-catalyzed cycloadditions, giving the corresponding cyclobutene cycloadducts in good yields. The sulfonyl-containing cycloadducts can be transformed into a variety of products that are difficult to obtain via direct cycloaddition.

Journal Article↗
PubMed2006

Synthesis of 2-arylcycloalka-2,4-dienones using sulfone-based methodology.

Addition of the anion derived from (phenylthiomethyl)phenyl sulfone to a selection of aryl omega-alkenyl ketones gives adducts that via a sequence of Lewis acid catalyzed rearrangement, alpha-allylation, and metathesis give rise to 2-thio-4-cycloalkenones. These in turn give cycloalkadienones upon oxidation and elimination. An attempt to develop a polymer-supported variant fails because of the reversibility of sulfone anion addition.

Journal Article↗
PubMed2000

Benzylic manganese halides, sulfonates, and phosphates: preparation, coupling reactions, and applications in organic synthesis

The use of highly active manganese, prepared by the Rieke method, for the direct preparation of benzylic manganese reagents was investigated. The oxidative addition of the highly active manganese (Mn) to benzylic halides was easily completed under mild conditions. More importantly, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. The majority of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. This approach also provided a facile synthetic route to the preparation of resorcinolic lipids.

Journal Article↗
PubMed2006

Perfluorobutane sulfonic acid hydration and interactions with O2 adsorbed on Pt3.

The side chain of NAFION, a proton conductive membrane used as electrolyte in low-temperature fuel cells, is modeled with perfluorobutane sulfonic acid. Density functional theory is used to characterize structures and energetics of hydration of the model system interacting with a proton solvated with up to 24 water molecules and analyze interactions of some of these hydrated complexes with O(2) adsorbed on Pt(3). It is found that at least three water molecules are needed to ionize the sulfonic acid, and higher degrees of hydration induce the formation of cages where the water molecules are held together via complex hydrogen-bond networks. The interaction between the complex formed by the ionized acid and the hydrated proton, in contact with a bridge-adsorbed O(2)-Pt(3), promotes the protonation of the adsorbed O(2). Upon protonation, the O(2)-Pt(3) system evolves from hydrophobic to hydrophilic behavior, which may facilitate further interfacial contact.

Journal Article↗
PubMed2006

Water-soluble multiwalled carbon nanotubes functionalized with sulfonated polyaniline.

Multiwalled carbon nanotubes (MWNTs) functionalized with a water-soluble conducting polymer, sulfonated polyaniline (SPAN), were prepared by in situ polymerization of aniline followed by sulfonation with chlorosulfonic acid in an inert solvent and by hydrolysis in water. Electron microscopy, laser Raman spectroscopy, X-ray photoelectron spectroscopy, and UV-vis absorption spectroscopy were employed to characterize the morphology and chemical structure of the resulting product. The results show that the quinonoid structure of SPAN preferentially interacts with the nanotubes and is stabilized by strong pi-pi interaction between two components. The structure of MWNTs was not perturbed by the incorporation of SPAN, since the pi-pi interaction between MWNTs and SPAN is much weaker in comparison to that of the carbon covalent bond. The SPAN functionalized MWNTs are highly dispersible in water, thus opening new possibilities for their prospective technological applications.

Journal Article↗
PubMed2006

Sonochemical degradation of alkylbenzene sulfonate surfactants in aqueous mixtures.

The degradation of nonvolatile surfactants sodium 4-octylbenzene sulfonate (OBS) and dodecylbenzenesulfonate (DBS) and a nonvolatile nonsurfactant 4-ethylbenzene sulfonic acid (EBS), as single components and binary mixtures, were studied under 354 kHz ultrasound. In addition, the effects of pulsed ultrasound on degradation were also examined. Results show that in mixtures of the surfactant OBS and nonsurfactant EBS, the surfactant is selectively degraded. The reduced degradation of EBS was dependent on the mixed molar ratio of EBS/OBS. The degradation of OBS was unaffected by the presence of EBS at a molar ratio of OBS/EBS > or = 1. Furthermore, OBS degradation was significantly enhanced under pulsed ultrasound. In OBS and DBS surfactant mixtures sonicated under pulsed ultrasound, surfactants strongly affected each other's degradation rates due to competition for the reaction sites on the cavitation bubble surfaces. OBS exhibits a faster degradation rate than DBS at shorter pulse intervals due to its faster rate of transfer to the cavitation bubble interfaces. At longer pulse intervals, DBS, which is more surface active, degrades faster than OBS due to the increased amounts of DBS accumulation on the bubble surfaces.

Journal Article↗
PubMed2005

Differences in binding of a cationic surfactant to cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) studied by Raman spectroscopy.

Raman spectroscopy has been used to investigate the structure of gel-surfactant complexes. Cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) were immersed in solutions of the cationic surfactant dodecyl trimethylammonium bromide. During the deswelling process, two distinct regions could be observed for both types of gels. Looking at the Raman spectra, however, for the poly(styrene sulfonate), the surfactant could be found throughout the gel particle, whereas for poly(acrylate), essentially all the surfactant was bound in a surface layer.

Acrylic Resins↗
PubMed2006

Positional isomers of linear sodium dodecyl benzene sulfonate: solubility, self-assembly, and air/water interfacial activity.

Commercial linear alkyl benzene sulfonates (ABS) are a very important class of anionic surfactants that are employed in a wide variety of applications, especially those involving wetting and detergency. Linear ABS surfactants generally consist of a complex mixture of different chain lengths and positional isomers. This diversity and level of complexity makes it difficult to develop fundamental structure-property correlations for the commercial surfactants. In this work, six monodisperse headgroup positional isomers of sodium para-dodecyl benzene sulfonate (Na-x-DBS, x = 1-6) have been studied. The influence of headgroup position and added electrolyte (NaCl) on the solubility and self-assembly (micellar and vesicular aggregation and lyotropic liquid crystalline phase behavior) in the temperature range from 10 to 90 degrees C have been investigated. Additionally, the air-aqueous solution interfacial adsorption at 25 (no added NaCl) and 50 degrees C (from 0 to 1.0 M added NaCl) has been examined. The observed physicochemical behavior is interpreted in terms of local molecular packing constraints, and in the case of the lyotropic liquid crystalline behavior global aggregate packing constraints as well.

Air↗
PubMed2002

Basic and reductive sulfone-directed ring-opening reactions of difluorinated oxa[2.2.1]bicycloheptanes.

Phenylsulfenyl chloride reacts with racemic endo Diels-Alder adduct 4 (DEC = CONEt(2)) to afford lactone 8, which can be reduced and protected in a series of high-yielding steps. Key sulfone 10 can be ring opened under strong base conditions to afford vinyl sulfone 11. Attempted desulfonation resulted in the formation of a monofluoroalkene, but a direct desulfonation/eliminative ring opening with strain relief delivered highly functionalized monocyclic species 16. [reaction: see text]

Journal Article↗
PubMed2004

Rhodium-catalyzed enantioselective conjugate addition of organoboronic acids to alpha,beta-unsaturated sulfones.

[reaction: see text] A general method for the enantioselective catalytic conjugate addition to acyclic alpha,beta-unsaturated sulfones is described. Using metal-chelating alpha,beta-unsaturated pyridyl sulfones as substrates, the rhodium-catalyzed chiraphos-mediated addition of organoboric acids takes place in excellent yield and high enantioselectivity. The subsequent elimination of the pyridylsulfonyl group by Julia-Kociensky olefination provides a novel approach to the enantioselective synthesis of allylic substituted alkenes.

Journal Article↗