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At least 721 records · Page 40Linked to original sources
PubMed1979

Interaction of alpha-chymotrypsin with the fluorescent probe 1-anilinonaphthalene-8-sulfonate in solution.

The binding of the fluorescence probe 1-anilinonaphthalene-8-sulfonate (Ans) to alpha-chymotrypsin (alpha-CHT) at pH 3.6 is accompanied by a dramatic enhancement of Ans fluorescence and a shift of the emission maximum to shorter wavelengths. Our study reveals that one Ans molecule binds to alpha-CHT at a site different from either the active site of alpha-CHT or the 2-p-toluidinylnapthalene-6-sulfonate binding site. the binding constant of Ans is about the same (10(4) M-1) at pH 3.6 and 6.4. Nanosecond fluorescence depolarization data indicate that Ans is rigidly bound to alpha-CHT. The fluorescence enhancement due to binding of Ans to alpha-CHT at low pH could be due to binding either to a hydrophobic site or to a site where local dipoles do not relax during the excited-state lifetime of Ans. As the pH is increased, fluorescence intensity of the Ans-alpha-CHT complex decreases appreciably; and the emission maximum shifts to longer wavelengths. The fluorescence decay curves exhibit a corresponding sensitivity to pH. The pH effect on the fluorescence of Ans-alpha-CHT can be interpreted in terms of a pH-dependent equilibrium between alpha-CHT conformers differing in the degree of mobility of polar residues and water molecules at the Ans binding site or structural changes in the Ans binding site.

Allosteric Site↗
PubMed1975

Neutral and Cationic Sulfonamido Derivatives of the Fluorescent Probe 2-p-Toluidinylnaphthalene-6-sulfonate. Properties and Mechanistic implications.

The sensitivity of the fluorescence energy of 2-p-toluidinylnaphthalene-6-sulfonate (TNS) to apparent solvent polarity is considerably greater in methanol-water mixtures and lower primary alcohols than in higher primary alcohols or solvents containing no hydroxyl groups. It is suggested that the behavior of TNS in lower alcohols and their mixtures with water is an anomalous result of the combination of general polarity influences and chanes in the nature of specific interactions of the probe with hydroxyl groups of such solvents. Upon conversion of the sulfonate group of TNS to sulfonamido, the biphasic behavior observed in alcohols is eliminated, and fluorescent probes are obtained which have more nearly equal sensitivites to polarity in the alcohols and nonhydroxyl solvents. The sulfonamido fluorescent probes are more sensitive to general environmental polarity than TNS, and are superior as probes of environmental polarity.

Binding Sites↗
PubMed2005

Steady-state and transient kinetic analyses of taurine/alpha-ketoglutarate dioxygenase: effects of oxygen concentration, alternative sulfonates, and active-site variants on the FeIV-oxo intermediate.

Taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD), an archetype alphaKG-dependent hydroxylase, is a non-heme mononuclear Fe(II) enzyme that couples the oxidative decarboxylation of alphaKG with the conversion of taurine to aminoacetaldehyde and sulfite. The crystal structure of taurine-alphaKG-Fe(II)TauD is known, and spectroscopic studies have kinetically defined the early steps in catalysis and identified a high-spin Fe(IV)-oxo reaction intermediate. The present analysis extends our understanding of TauD catalysis by investigating the steady-state and transient kinetics of wild-type and variant forms of the enzyme with taurine and alternative sulfonates. TauD proteins substituted at residues surrounding the active site were shown to fold properly based on their abilities to form a diagnostic chromophore associated with the anaerobic Fe(II)-alphaKG chelate complex and to generate a tyrosyl radical upon subsequent reaction with oxygen. Steady-state studies of mutant proteins confirmed the importance of His 70 and Arg 270 in binding the sulfonate moiety of taurine and indicated the participation of Asn 95 in recognizing the substrate amine group. The N97A and S158A variants are likely to undergo an increase in hydrophobicity and expansion of the substrate-binding pocket, thus accounting for their decreased K(m) toward pentanesulfonic acid compared to wild-type TauD. Stopped-flow UV-visible spectroscopic examination of the reaction of oxygen with taurine-alphaKG-Fe(II)TauD confirmed a minimal three-step sequence of reactions attributed to Fe(IV)-oxo formation (k(1)), bleaching to the Fe(II) state upon substrate hydroxylation (k(2)), rebinding of excess substrates (k(3)), and indicated that none of the steps exhibit detectable solvent k(H)/k(D) isotope effects. This demonstrates that no protons are involved in the rate-determining step of Fe(IV)-oxo formation, in contrast to heme iron oxygenases. The Fe(IV)-oxo species is likely to be utilized in conversion of the alternative substrates pentanesulfonic acid and 3-N-morpholinopropanesulfonic acid; however, this spectroscopic intermediate was not detected because of the decreased k(1)/k(2) ratio. With taurine, k(1) was shown to depend on the oxygen concentration allowing calculation of a second-order rate constant of 1.58 x 10(5) M(-)(1) s(-)(1) for this irreversible reaction. Stopped-flow analyses of TauD variants provided several insights into how the protein environment influences the rates of Fe(IV)-oxo formation and decay. The Fe(IV)-oxo species was not detected in the N95D or N95A variants because of a reduced k(1)/k(2) ratio, likely related to a decreased substrate-dependent conversion of the six-coordinate to five-coordinate metal site.

Alkanesulfonates↗
PubMed2004

The stereoselectivity and catalytic properties of Xanthobacter autotrophicus 2-[(R)-2-Hydroxypropylthio]ethanesulfonate dehydrogenase are controlled by interactions between C-terminal arginine residues and the sulfonate of coenzyme M.

2-[(R)-2-Hydroxypropylthio]ethanesulfonate (R-HPC) dehydrogenase (DH) catalyzes the reversible oxidation of R-HPC to 2-(2-ketopropylthio)ethanesulfonate (2-KPC) in a key reaction in the bacterial conversion of chiral epoxides to beta-keto acids. R-HPCDH is highly specific for the R-enantiomer of HPC, while a separate enzyme, S-HPCDH, catalyzes the oxidation of the corresponding S-enantiomer. In the present study, the features of substrate and enzyme imparting stereospecificity have been investigated for R-HPCDH. S-HPC was a substrate for R-HPCDH with a K(m) identical to that for R-HPC but with a k(cat) 600 times lower. Achiral 2-propanol and short-chain (R)- and (S)-2-alkanols were substrates for R-HPCDH. For (R)-alkanols, as the carbon chain length increased, K(m) decreased, with the K(m) for (R)-2-octanol being 1700 times lower than for 2-propanol. At the same time, k(cat) changed very little and was at least 90% lower than k(cat) for R-HPC and at least 22 times higher than k(cat) for S-HPC. (S)-2-Butanol and (S)-2-pentanol were substrates for R-HPCDH. The K(m) for (S)-2-butanol was identical to that for (R)-2-butanol, while the K(m) for (S)-2-pentanol was 7.5 times higher than for (R)-2-pentanol. Longer chain (S)-2-alkanols were sufficiently poor substrates for R-HPCDH that kinetic parameters could not be determined. Mutagenesis of C-terminal arginine residues of R-HPCDH revealed that R152 and R196 are essential for effective catalysis with the natural substrates R-HPC and 2-KPC but not for catalysis with 2-alkanols or ketones as substrates. Short-chain alkylsulfonates and coenzyme M (2-mercaptoethanesulfonate) were found to modify the kinetic parameters for 2-butanone reduction by R-HPCDH in a saturable fashion, with the general effect of increasing k(cat), decreasing K(m), and increasing the enantioselectivity of 2-butanone reduction to a theoretical value of 100% (S)-2-butanol. The modulating effects of ethanesulfonate and propanesulfonate provided thermodynamic binding constants close to K(m) for the natural substrates R-HPC and 2-KPC. The effects of alkylsulfonates on modulating the enantioselectivity and kinetic properties of R-HPCDH were abolished in R152A and R196A mutants but not in mutants of other C-terminal arginine residues. Collectively, the results suggest that interactions between the sulfonate of CoM and specific arginine residues are key to the enantioselectivity and catalytic efficiency of R-HPCDH. A model is proposed wherein sulfonate-arginine interactions within an alkylsulfonate binding pocket control the catalytic properties of R-HPCDH.

Alcohol Oxidoreductases↗
PubMed2007

Chitinase-catalyzed synthesis of an alternatingly N-sulfonated chitin derivative.

An alternatingly N-sulfonated chitin derivative (2) was synthesized via ring-opening polyaddition of an N-sulfonated chitobiose oxazoline derivative (1) catalyzed by chitinases from Bacillus sp. and Serratia marcescens. The polymerization proceeded homogeneously, providing 2 as a water-soluble polysaccharide in good yields with total control of regioselectivity and stereochemistry. M(n) of 2 reached 1900 and 4180 by use of chitinases from Bacillus sp. and Serratia marcescens, which correspond to 8-10 (n = 4-5) and 18-20 (n = 9-10) saccharide units, respectively. These results indicate that M(n) of 2 is controllable by selecting chitinases from different origins. It is considered that the C-2 position of the nonreducing unit in the oxazoline-type monomer is not deeply involved in the catalysis of chitinase.

Bacillus↗
PubMed1998

Protein adsorption characteristics of a sulfonic-acid-group-containing nonwoven fabric

A sulfonic acid (SO3H)-group-containing nonwoven fabric was prepared by radiation-induced graft polymerizaton of an epoxy-group-containing monomer, glycidyl methacrylate, onto a nonwoven fabric and subsequent sulfonation. The nonwoven fabric containing SO3H groups at different densities was equilibrated with lysozyme in a buffer (pH 6.0). The equilibrium binding capacity (EBC) of lysozyme increased linearly with increasing SO3H group density. The SO3H-group-containing polymer chains extended from the pore surface due to mutual electrostatic repulsion and held lysozyme in multilayers. The maximum EBC was 0.7 kg/kg at a SO3H group density of 1.7 mol/kg.

Journal Article↗
PubMed2004

Biodegradation of linear alkylbenzene sulfonates and their degradation intermediates in seawater.

A study has been made of the aerobic biodegradation of linear alkylbenzene sulfonates (C12 and C11 homologues) and sulfophenylcarboxylic acids (C5 and C11 homologues) in seawater at concentrations of the same order as those detected ones in coastal waters influenced by wastewater effluents, at different temperatures, and both with and without the addition of an inoculum adapted to the presence of linear alkylbenzene sulfonate (LAS). The biodegradation of C12LAS, C11LAS, C5SPC, and C11SPC exceeds 99% in all tests performed and can be satisfactorily fitted to a second-degree polynomial without an independent term. The kinetic of degradation of LAS presents a clear seasonal component, since the process is considerably inhibited at lower temperatures; it is also kinetically enhanced by the presence of the inoculum. The intermediates detected for all the cases are sulfophenylcarboxylic acids (SPCs), the most abundant being those intermediates produced by the omega- and beta-oxidations of the parent compound, although intermediates produced by the alpha-oxidation have also been detected. The kinetic of the SPCs generated can be described using a model composed of two terms that represent the formation and the degradation of these intermediates. The total disappearance of the SPCs in all cases indicates that the degradation of LAS in seawater at the tested concentrations in aerobic conditions is complete.

Alkanesulfonic Acids↗
PubMed2006

Perfluorinated contaminants in sediments and aquatic organisms collected from shallow water and tidal flat areas of the Ariake Sea, Japan: environmental fate of perfluorooctane sulfonate in aquatic ecosystems.

Perfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHS), and perfluorooctane sulfonamide (PFOSA) are widely distributed in aquatic ecosystems. Despite studies reporting the occurrence of PFCs in aquatic organisms, the fate of PFCs in tidal flat and marine coastal ecosystems is not known. In this study, we determined concentrations of PFOS, PFOA, PFNA, PFHS, and PFOSA in sediments; benthic organisms, including lugworm, mussel, crab, clam, oyster, and mudskipper fish from tidal flat; and shallow water species, such as filefish, bream, flounder, shark, finless porpoise, gull, and mallard collected from the Ariake Sea, Japan. PFOS and PFOA were detected in most of the samples analyzed, followed by PFNA, PFOSA, and PFHS. In shallow water species, PFOS was the dominant contaminant, and elevated concentrations were found in higher trophic level species, such as marine mammals and omnivorous birds. These results suggest biomagnification of PFOS through the coastal food chain. In contrast, PFOA was the most abundant compound in tidal flat organisms and sediments. PFOA concentrations in sediments, lugworms, and omnivorous mudskippers in tidal flat were approximately 1 order of magnitude greater than the levels of PFOS. This indicates differences in exposure pattern and bioavailability of PFOS and PFOA between shallow water and tidal flat organisms. The accumulation profiles of PFCs were compared with those of organochlorines (polychlorinated biphenyls, PCB), organotin (tributyltin,TBT), and polycyclic aromatic hydrocarbons (PAHs) in tidal flat and shallow water samples collected from the Ariake Sea. Concentrations of PFCs in sediments and in tidal flat organisms were significantly lower than that found for PCBs, TBT, and PAHs. Nevertheless, PFOS concentrations in shallow water species were comparable to and/or significantly greater than those of other classes of contaminants. This implies that the aqueous phase is a major sink for PFCs, which is different from what was observed for nonpolar organic pollutants.

Alkanesulfonic Acids↗
PubMed2000

Reduction of inner sulfonium salts, thioethers, and sulfones derived from closo-[B12H12]2- by lithium in methylamine: a new route to mercaptododecaborates.

Anions [Me2SB12H11]- (2) and [MeSB12H11]2- (3) can be reduced by excess lithium in methylamine at -15 degrees C to yield [HSB12H11]2- (1) after workup. Such behavior toward this reducing system is similar to that of alkyl aryl sulfides. The sulfone [MeSO2B12H11]2- (12) also yields 1 as a major boron product upon reduction, while alkyl aryl sulfones produce the corresponding arenes under the same conditions. Similarly, isomers of (Me2S)2B12H10 (4-6) are reduced by lithium in methylamine yielding dithiols [(HS)2B12H10]2- (7-9). The tetrabutylammonium salts of 1 and 7-9 are obtained in 80-90% yields and characterized by multinuclear NMR and mass spectrometry, the latter three compounds being isolated and characterized for the first time. The reduction reaction provides access to dithiols 7-9 for biological evaluation and use in synthesis. Thus, 2 and 4-6 can be easily converted to [R2SB12H11]- and (R2S)2B12H10 in a two-step reduction-alkylation procedure. 1,2-(Bn2S)2B12H10 (13) obtained by alkylation of the reduction product of 4 by benzyl chloride was characterized by single-crystal X-ray diffraction analysis. Crystal data for 1,2-(Bn2S)2B12H10.CD3CN: C2/c (No. 15), a = 13.666(1) A, b = 16.978(1) A, c = 14.667(1) A, beta = 91.08(1) degrees, Z = 4.

Journal Article↗
PubMed2004

Syntheses, crystal structures, and luminescent properties of novel layered lanthanide sulfonate-phosphonates.

Hydrothermal reactions of lanthanide metal salts with MeN(CH(2)CO(2)H)(CH(2)PO(3)H(2)) (H(3)L) and 5-sulfoisophthalic acid monosodium salt (NaH(2)BTS) lead to four isomorphous lanthanide carboxylate-phosphonate-sulfonate hybrids, namely, Ln(H(2)L)(HBTS)(H(2)O)(2).H(2)O (Ln = La (1), Pr (2), Nd (3), Gd (4)). Their structures have been established by X-ray single-crystal diffraction. The interconnection of the lanthanide(III) ions by carboxylate-phosphonate ligands results in a 1D double chain; these double chains are further bridged by bidentate bridging carboxylate-sulfonate ligands to form a <011> layer. The luminescent properties of compounds 3 and 4 have also been studied.

Alkanesulfonates↗
PubMed2006

Rational design of 0D, 1D, and 3D open frameworks based on tetranuclear lanthanide(III) sulfonate-phosphonate clusters.

Hydrothermal reactions of lanthanide(III) salts with m-sulfophenylphosphonic acid (H3L1) and 1,10-phenanthroline (phen) or N,N'-piperazinebis(methylenephosphonic acid) (H4L2) afforded six novel lanthanide(III) sulfonate-phosphonates based on tetranuclear clusters, namely, [La(2)(L1)2(phen)4(H2O)].4.5H2O (1), [Ln2(L1)2(phen)2(H2O)5].3H2O (Ln = Nd, 2; Eu, 3; Er, 4), and [Ln2(HL1)(H2L2)2(H2O)4].8H2O (Ln = La, 5; Nd, 6). Compounds 2-4 contain discrete tetranuclear lanthanide(III) cluster units in which four lanthanide(III) ions are bridged by two tridentate and two tetradentate phosphonate groups. In compound 1, the tetranuclear clusters are further interconnected into a 1D chain through the coordination of the sulfonate groups. The structures of compounds 5 and 6 can be viewed as a 3D architecture based on a different types of tetranuclear cluster units that are interconnected by bridging H2L2 anions. In the tetranuclear clusters of compounds 5 and 6, the four lanthanide(III) centers are interconnected by only two HL1 ligands. Compound 2 is a luminescent material in the near-IR region, whereas compound 3 displays a strong luminescent emission band in the red-light region. Magnetic property measurements of compounds 2-4 and 6 indicate that there are strong antiferromagetic interactions between magnetic centers within the cluster units.

Journal Article↗
PubMed2003

Sulfonated microporous organic-inorganic hybrids as strong Bronsted acids.

It has been discovered that the use of excess zirconium in reactions with 4,4'-biphenyl and 4,4'-terphenylbis(phosphonic acid) in DMSO or DMSO-ethanol mixtures produces microporous inorganic-organic hybrids. Surface areas of 400 m(2)/g and pore sizes in the range of 10-20 A in diameter are routinely obtained. These materials are readily sulfonated with SO(3) under pressure to yield strong Bronsted acids. The acid strength, measured by (13)C NMR shifts of acetone and cyclopentanone in contact with the sulfonates, indicates an acidity close to that of 100% H(2)SO(4). Condensation and cracking reactions were obtained for both ketones under mild conditions. A working hypothesis is presented to account for the high surface area and microporosity. The combination of high surface areas and pore dimensions that are between those of zeolites and mesoporous silicas commends these materials for applications in separations, ion exchange, and catalysis.

Journal Article↗
PubMed2005

Chiral phosphine lewis bases catalyzed asymmetric aza-Baylis-Hillman reaction of N-sulfonated imines with activated olefins.

In the aza-Baylis-Hillman reaction of N-sulfonated imines (N-arylmethylidene-4-methylbenzenesulfonamides and others) with methyl vinyl ketone, ethyl vinyl ketone, and acrolein, we found that, in the presence of a catalytic amount of chiral phosphine Lewis base such as (R)-2'-diphenylphosphanyl-[1,1']binaphthalenyl-2-ol LB1 (10 mol %) and molecular sieve 4A, the corresponding aza-Baylis-Hillman adducts could be obtained in good yields with good to high ee (70-95% ee) at low temperature (approximately -30 to -20 degrees C) or at room temperature in THF, respectively. In CH2Cl2 upon heating at 40 degrees C, the aza-Baylis-Hillman reaction of N-sulfonated imines with phenyl acrylate or naphthyl acrylate gave the adducts in good to high yields (60-97%) with moderate ee (52-77%). The mechanistic insight has been investigated by 31P and 1H NMR spectroscopic measurements. The key enolate intermediate, which has been stabilized by intramolecular hydrogen bonding, has been observed by 31P and 1H NMR spectroscopy. An effective bifunctional Lewis base and Bronsted acid phosphine Lewis base system has been disclosed in this catalytic, asymmetric aza-Baylis-Hillman reaction.

Journal Article↗
PubMed1993

Design, synthesis, and pharmacology of 3-substituted sodium azulene-1-sulfonates and related compounds: non-prostanoid thromboxane A2 receptor antagonists.

A series of novel azulene-1 carboxylic acid derivatives 28-30, azulene-1 sulfonic acid sodium salts 41a-c, and related compounds were synthesized. These compounds were tested for TXA2 receptor antagonistic activity. The inhibitory concentrations (IC50) of these compounds for vascular contraction (TXA2 tau receptor) and platelet aggregation (TXA2 alpha receptor) induced by (15S)-15-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5(Z),13(E)- dienoic acid (U-46619) were obtained. Azulene-1-sulfonic acid sodium salts 41a-c were over 3 times more potent than azulene-1-carboxylic acids 28-30. The most potent compound, 41b was 4 orders of magnitude more potent than a TXA2 antagonist, BM13,177, in inhibiting vascular contraction (tau receptor) and had an IC50 of 9.0 x 10(-10) M. Compound 41b was also found to be a tau receptor selective antagonist (IC50 of contraction/IC50 of aggregation = 378) and to have no TXA2 synthetase inhibitory activity at concentrations up to 10(-4) M and no partial agonistic activity at concentrations up to 10(-5) M in rabbit aorta (tau receptor) and up to 10(-4) M in rabbit platelet-rich plasma (alpha receptor). In a radioligand binding assay using rabbit gel-filtered platelets, compound 41b had a high-affinity binding for the TXA2 receptor. In an in vivo study, compound 41b inhibited U-46619-induced sudden death in mice at a dose of 0.3 mg/kg and its duration of action was over 8 h when administered orally at 3 mg/kg.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1986

Inactivation of leukocyte elastase by aryl azolides and sulfonate salts. Structure-activity relationship studies.

The inhibitory activity of a series of aryl azolides and sulfonate salts toward human leukocyte elastase is reported. Several of the compounds were found to be potent inhibitors of the enzyme. Active compounds were obtained only when the specificity group and the reactive moiety were separated by a two-carbon chain. The introduction of hydrophobic groups enhanced the inhibitory activity of these compounds, with the exception of the sulfonate salts. The nature of the leaving group had a profound effect on inhibitory activity, with compounds 23 and 26 being the most active (kobsd/[I] = 11,722 and 13,500 M-1 s-1, respectively).

Azo Compounds↗
PubMed1983

Antibacterially active substituted anilides of carboxylic and sulfonic acids.

Anilides of carboxylic and sulfonic acids were prepared and tested for antimicrobial activity. While these anilides were ineffective against Gram-negative organisms, there was a good correlation between chemical structure and biological activity against Gram-positive species. Both the nature and position of the benzene ring substituents and the length of the carbon side chain affected the activity and specificity of the compounds. The highest activity was observed when the acyl or sulfuryl moiety had a C7-C9 side chain attached. The CONH and SO2NH bridging groups were equally effective. The attachment of COOH or COOCH3 groups in the omega-position did not effect activity, but the substitution of the acidic proton of the sulfonamide group by an alkyl group rendered the compound inactive. Six compounds, which were substituted anilides of sulfonic acids, fatty acids, or the analagous alpha-methylene-substituted acids, were bacteriostatic at 10 ppm against Bacillus cereus, Staphylococcus aureus, Streptococcus faecalis, and Lactobacillus plantarum. One of these compounds, 2-hydroxy-5-nitroanilide of alpha-methylenedecanoic acid, was bactericidal at 1 ppm.

Anilides↗
PubMed2002

Phenoxyphenyl sulfone N-formylhydroxylamines (retrohydroxamates) as potent, selective, orally bioavailable matrix metalloproteinase inhibitors.

A novel series of sulfone N-formylhydroxylamines (retrohydroxamates) have been investigated as matrix metalloproteinases (MMP) inhibitors. The substitution of the ether linkage of ABT-770 (5) with a sulfone group 13a led to a substantial increase in activity against MMP-9 but was accompanied by a loss of selectivity for inhibition of MMP-2 and -9 over MMP-1 and diminished oral exposure. Replacement of the biphenyl P1' substituent with a phenoxyphenyl group provided compounds that are highly selective for inhibition of MMP-2 and -9 over MMP-1. Optimization of the substituent adjacent to the retrohydroxamate center in this series led to the clinical candidate ABT-518 (6), a highly potent, selective, orally bioavailable MMP inhibitor that has been shown to significantly inhibit tumor growth in animal cancer models.

Administration, Oral↗
PubMed2001

Development of a new carbon-carbon bond forming reaction. new organic chemistry of sulfur dioxide. Asymmetric four-component synthesis of polyfunctional sulfones.

At low temperature 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or Brønstedt acid and generate zwitterionic intermediates that can be quenched by enoxysilanes. The resulting beta,gamma-unsaturated silyl sulfinates can be desilylated and reacted with methyl iodide to provide polyfunctional sulfones. Exploratory studies of this four-component synthesis of sulfones are reported. Enantiomerically pure derivatives containing up to three new stereogenic centers can be obtained using enantiomerically pure (E,E)-1-alkoxy-2-methylpenta-1,3-dienes derived from alpha-methyl benzyl alcohols, including the Greene's chiral auxiliary. The stereochemistry of the reactions is consistent with a mechanism involving the suprafacial hetero-Diels-Alder addition of sulfur dioxide to the 1-alkoxy-1,3-dienes that are rapidly ionized into zwitterionic intermediates.

Journal Article↗