- Strecker-type degradation produced by the lipid oxidation products 4,5-epoxy-2-alkenals
-
Strecker degradation is one of the most important reactions leading to final aroma compounds in the Maillard reaction. In an attempt to clarify whether lipid oxidation products may be contributing to the Strecker degradation of amino acids, this study analyzes the reaction of 4,5-epoxy-2-alkenals with phenylalanine. In addition to N-substituted 2-(1-hydroxyalkyl)pyrroles and N-substituted pyrroles, which are major products of the reaction, the formation of both the Strecker aldehyde phenylacetaldehyde and 2-alkylpyridines was also observed. The aldehyde, which was produced at 37°C - as could be determined by forming its corresponding thiazolidine with cysteamine - and pH 6-7, was not produced when the amino acid was esterified. This aldehyde is suggested to be produced through imine formation, which is then decarboxylated and hydrolyzed. This reaction also produces a hydroxyl amino derivative, which is the origin of the 2-alkylpyridines identified. All these data indicate that Strecker-type degradation of amino acids is produced at 37°C by some lipid oxidation products. This is a new proof of the interrelations between lipid oxidation and Maillard reaction, which are able to produce common products by analogue mechanisms.
- Hidalgo, Francisco J.,Zamora, Rosario
-
-
Read Online
- Methylene Blue as a Photosensitizer and Redox Agent: Synthesis of 5-Hydroxy-1H-pyrrol-2(5H)-ones from Furans
-
A highly efficient and general singlet-oxygen-initiated one-pot transformation of readily accessible furans into 5-hydroxy-1H-pyrrol-2(5H)-ones has been developed. The methodology was extended to the synthesis of other high-value α,β-unsaturated γ-lactams. This useful set of transformations relies not only on the photosensitizing ability of methylene blue, but also on its redox properties: properties that have until now been virtually ignored in a synthetic context
- Kalaitzakis, Dimitris,Kouridaki, Antonia,Noutsias, Dimitris,Montagnon, Tamsyn,Vassilikogiannakis, Georgios
-
-
Read Online
- Assisted tandem catalytic RCM-aromatization in the synthesis of pyrroles and furans
-
An assisted tandem catalytic transformation of diallyl amines and diallyl ethers into N-aryl pyrroles and furans, respectively, is described. The sequence relies on ring closing metathesis followed by dehydrogenation of the initially formed dihydropyrroles and dihydrofurans. Both steps are Ru-catalyzed, but the sequence requires only one precatalyst, because conversion of the metathesis catalyst into the dehydrogenation catalyst is achieved in situ, triggered by the oxidant tert-butyl hydroperoxide.
- Schmidt, Bernd,Krehl, Stefan,Jablowski, Eric
-
p. 5119 - 5130
(2012/08/07)
-
- The scent of bacteria: Headspace analysis for the discovery of natural products
-
Volatile compounds released by 50 bacterial strains, 45 of them actinobacteria in addition to three chloroflexi and two myxobacteria, have been collected by use of a closed-loop stripping apparatus, and the obtained headspace extracts have been analyzed by GC-MS. Excluding terpenes that have recently been published elsewhere, 254 compounds from all kinds of compound classes have been identified. For unambiguous compound identification several reference compounds have been synthesized. Among the detected volatiles 12 new natural products have been found, in addition to mellein, which was released by Saccharopolyspora erythraea. The iterative PKS for this compound has recently been identified by in vitro experiments, but mellein production in S. erythraea has never been reported before. These examples demonstrate that headspace analysis is an important tool for the discovery of natural products that may be overlooked using conventional techniques. The method is also useful for feeding experiments with isotopically labeled precursors and was applied to investigate the biosynthesis of the unusual nitrogen compound 1-nitro-2-methylpropane, which arises from valine. Furthermore, several streptomycetes emitted compounds that were previously recognized as insect pheromones, thus questioning if bacterial symbionts are involved in insect communication.
- Citron, Christian A.,Rabe, Patrick,Dickschat, Jeroen S.
-
supporting information
p. 1765 - 1776
(2013/01/15)
-
- Amino acid catalysis of 2-alkylfuran formation from lipid oxidation-derived α,β-unsaturated aldehydes
-
The formation of 2-alkylfurans from the corresponding lipid-derived α,β-unsaturated aldehydes under dry-roasting conditions was investigated in detail. The addition of an amino acid to an α,β- unsaturated aldehyde drastically increased 2-alkylfuran formation. Peptides and proteins as well were able to catalyze 2-alkylfuran formation from the corresponding α,β-unsaturated aldehydes. Further investigation of 2-alkylfuran formation showed the need of oxidizing conditions and the involvement of radicals in the reaction. This way, the formation of 2-methylfuran from 2-pentenal, 2-ethylfuran from 2-hexenal, 2-propylfuran from 2-heptenal, 2-butylfuran from 2-octenal, 2-pentylfuran from 2-nonenal, and 2-hexylfuran from 2-decenal was shown. The impact of amino acids on 2-alkylfuran formation from lipid-derived α,β-unsaturated aldehydes represents an interesting example of the complex role of amino acids in the multitude of chemical reactions occurring during thermal processing of lipid-rich foods.
- Adams, An,Bouckaert, Capucine,Van Lancker, Fien,De Meulenaer, Bruno,De Kimpe, Norbert
-
experimental part
p. 11058 - 11062
(2012/02/06)
-
- Synthesis of deuterium-labeled analogs of the lipid hydroperoxide-derived bifunctional electrophile 4-oxo-2(E)-nonenal
-
Lipid hydroperoxides undergo homolytic decomposition into the bifunctional 4-hydroxy-2(E)-nonenal and 4-oxo-2(E)-nonenal (ONE). These bifunctional electrophiles are highly reactive and can readily modify intracellular molecules including glutathione (GSH), deoxyribonucleic acid (DNA) and proteins. Lipid hydroperoxide-derived bifunctional electrophiles are thought to contribute to the pathogenesis of a number of diseases. ONE is an α,β-unsaturated aldehyde that can react in multiple ways and with glutathione, proteins and DNA. Heavy isotope-labeled analogs of ONE are not readily available for conducting mechanistic studies or for use as internal standards in mass spectrometry (MS)-based assays. An efficient one-step cost-effective method has been developed for the preparation of C-9 deuterium-labeled ONE. In addition, a method for specific deuterium labeling of ONE at C-2, C-3 or both C-2 and C-3 has been developed. This latter method involved the selective reduction of an intermediate alkyne either by lithium aluminum hydride or lithium aluminum deuteride and quenching with water or deuterium oxide. The availability of these heavy isotope analogs will be useful as internal standards for quantitative studies employing MS and for conducting mechanistic studies of complex interactions between ONE and DNA bases as well as between ONE and proximal amino acid residues in peptides and proteins. Copyright
- Arora, Jasbir S.,Oe, Tomoyuki,Blair, Ian A.
-
scheme or table
p. 247 - 251
(2012/02/03)
-
- (2E)-4-hydroxyalk-2-enals and 2-substituted furans as products of reactions of (2E)-4,4-dimethoxybut-2-enal with Grignard compounds
-
Methods have been developed for the synthesis of (2E)-1,1-dimethoxyalk-2- en-4-ols and (2E)-4-hydroxyalk-2-enals by reaction of (2E)-4,4-dimethoxybut-2- enals and Grignard compounds. Thermal isomerization of (2E)-4-hydroxyalk-2-enals gave the corresponding 2-alkylfurans.
- Garibyan,Ovanesyan,Makaryan,Petrosyan,Chobanyan
-
experimental part
p. 406 - 409
(2010/09/12)
-
- Effect of oxidized arachidonic acid and hexanal on the mouse taste perception of bitterness and umami
-
The oxidization of fatty acids generates many volatile compounds forming an aroma, but little is known whether mammals use gustatory sense to detect the oxidized products as a taste or only use olfactory sense to detect as an aroma. We examined in this study the effect of aqueous extracts of the compounds from autoxidized arachidonic acid (AA) ethyl ester or hexanal which is the predominant component generated from oxidized AA by the anosmic mouse licking performance to a tastant. The addition of the water extract from oxidized AA or hexanal to a quinine hydrochloride (QHC1) solution decreased the anosmic mice licking frequency at several concentrations of QHC1. Hexanal also reduced the licking frequency of anosmic mice conditioned to avoid MSG at several concentrations of monosodium glutamate (MSG). These results suggest that hexanal would affect mouse taste perception to QHC1 and MSG via the gustatory sensation.
- Yamaguchi, Susumu,Fujiwara, Hidenori,Tashima, Ikukazu,Iwanaga, Daigo,Ushio, Hideki
-
experimental part
p. 1884 - 1890
(2011/06/17)
-
- Model studies on the degradation of phenylalanine initiated by lipid hydroperoxides and their secondary and tertiary oxidation products
-
The reaction of methyl 13-hydroperoxyoctadeca-9,11-dienoate (MeLOOH), methyl 13-hydroperoxyoctadeca-9,11,15-trienoate (MeLnOOH), methyl 13-hydroxyoctadeca-9,11-dienoate (MeLOH), methyl 13-oxooctadeca-9,11-dienoate (MeLCO), methyl 9,10-epoxy-13-hydroxy-11-octadecenoate (Me-LEPOH), and methyl 9,10-epoxy-13-oxo-11-octadecenoate (MeLEPCO) with phenylalanine was studied to determine the comparative reactivity of primary, secondary, and tertiary lipid oxidation products in the Strecker degradation of amino acids. All assayed lipids were able to degrade the amino acid to a high extent, although the lipid reactivity decreased slightly in the following order: MeLEPCO ≥ MeLCO > MeLEPOH ≥ MeLOH > MeLOOH ≈ MeLnOOH. These data confirmed the ability of many lipid oxidation products to degrade amino acids by a Strecker-type mechanism and suggested that, once the lipid oxidation is produced, a significant Strecker degradation of surrounding amino acids should be expected. The contribution of different competitive mechanisms to this degradation is proposed, among which the conversion of the different lipid oxidation products assayed into the most reactive MeLEPCO and the fractionation of long-chain primary and secondary lipid oxidation products into short-chain aldehydes are likely to play a major role.
- Zamora, Rosario,Gallardo, Emerenciana,Hidalgo, Francisco J.
-
experimental part
p. 7970 - 7975
(2010/03/30)
-
- Efficient one-pot synthesis of 2-substituted furans from 3,3-diethoxypropyne and aldehydes using a Ti(O-i-Pr)4/2i-PrMgCl reagent
-
A new, efficient and direct synthetic method for synthesizing 2-substituted furans using titanium-alkyne complex from easily preparable lithium propargyl alcohol derivatives derived from commercially available 3,3-diethoxypropyne, n-butyllithium and aldehydes by a Ti(O-i-Pr)4/2 i-PrMgCl reagent in 68-85percent yields.
- Eom, Deok Ki,Choi, Seong Jib,An, Duk Keun
-
p. 1141 - 1146
(2008/02/08)
-
- Amine degradation by 4,5-epoxy-2-decenal in model systems
-
The reactions of 4,5-epoxy-2-decenal with octylamine, benzylamine, and 2-phenylglycine methyl ester were studied to investigate if amines may suffer a Strecker type degradation by epoxyalkenals analogously to amino acids. In addition to other reactions, the studied amines were converted into their corresponding Strecker aldehydes (octanal, benzaldehyde, and methyl 2-oxo-2-phenylacetate, respectively) to an extent that depended on the pH, the temperature, the amount of epoxyalkenal, and the amine involved. Each amine exhibited an optimum pH for the reaction, but the corresponding Strecker aldehydes were produced to a significant extent within a broad pH range. In addition, the temperature mostly influenced the reaction rate, which was increased between 6.5 and 9.5 times when the reaction was carried out at 60°C than when it took place at 37°C. Furthermore, Strecker aldehyde formation was linearly correlated with the amount of the epoxyalkenal present in the reaction mixture. Nevertheless, the reaction yield mostly depended on the amine involved. Thus, octylamine only produced trace amounts of octanal, benzylamine was converted into benzaldehyde with a yield of 4.3%, and 2-phenylglycine methyl ester was converted into methyl 2-oxo-2-phenylacetate with a reaction yield of 49%. All of these results suggest that suitable amines can be degraded by epoxyalkenals to their corresponding Strecker aldehydes to a significant extent.
- Zamora, Rosario,Gallardo, Emerenciana,Hidalgo, Francisco J.
-
p. 2398 - 2404
(2007/10/03)
-
- Strecker type degradation of phenylalanine by 4-hydroxy-2-nonenal in model systems
-
The reaction of 4-hydroxy-2-nonenal, an oxidative stress product, with phenylalanine in acetonitrile-water (2:1, 1:1, and 1:2) at 37, 60, and 80°C was investigated to determine whether 4-hydroxy-2-alkenals degrade amino acids, analogously to 4,5-epoxy-2-alkenals, and to compare the reactivities of both hydroxyalkenals and epoxyalkenals for production of Strecker aldehydes. In addition to the formation of N-substituted 2-pentylpyrrole and 2-pentylfuran, the studied hydroxyalkenal also degraded phenylalanine to phenylacetaldehyde with a reaction yield of 17%. The reaction mechanism is suggested to be produced through the corresponding imine, which is then decarboxylated and hydrolyzed. This reaction also produced a conjugated amine, which both may be one of the origins of the produced 2-pentyl-1H -pyrrole and may contribute to the development of browning in these reactions. 4-Hydroxy-2-nonenal and 4,5-epoxy-2-decenal degraded phenylalanine in an analogous extent, which is likely a consequence of the similarity of the degradation mechanisms involved. These results suggest that different lipid oxidation products are able to degrade amino acids; therefore, the Strecker type degradation of amino acids produced by oxidized lipids may be quantitatively significant in foods.
- Hidalgo, Francisco J.,Gallardo, Emerenciana,Zamora, Rosario
-
p. 10254 - 10259
(2007/10/03)
-
- A synthesis of densely functionalized 2,3-dihydropyrans using ring-closing metathesis and base-induced rearrangements of dihydropyran oxides
-
The preparation of dihydropyran and dihydrofuran oxides and their rearrangement in the presence of lithium dialkylamides to functionalized 2,3-dihydropyrans or 2,3-dihydrofurans, respectively, is described. The regiochemical outcome of the reaction can be influenced by the relative configuration of the starting epoxides and the steric demand of the base. The 2,3-dihydropyrans obtained were converted stereoselectively to difunctionalized 3,4-dihydropyrans by the carbon-Ferrier reaction, or to fused acetals by addition of dimedone, mediated by ceric ammonium nitrate. The stereochemical results are rationalized by mechanistic proposals.
- Schmidt, Bernd,Wildemann, Holger
-
p. 3145 - 3163
(2007/10/03)
-
- Addition of carbon nucleophiles to aldehyde tosylhydrazones of aromatic and heteroaromatic-compounds: Total synthesis of piperine and its analogs
-
Addition of carbon nucleophiles to aldehyde tosylhydrazones of aromatic and heteroaromatic compounds is reported. New observations have been made wherein alkylative reduction is observed in some cases whereas alkylative fragmentation is noticed in others. These findings are exploited in the synthesis of the useful alkaloid piperine and its analogs. (C) 2000 Elsevier Science Ltd.
- Chandrasekhar,Venkat Reddy,Srinivasa Reddy,Ramarao
-
p. 2667 - 2670
(2007/10/03)
-
- A general and facile synthesis of substituted furans by palladium- catalyzed cycloisomerization of (Z)-2-en-4-yn-1-ols
-
A general and facile synthesis of furans, based on Pd(II)-catalyzed cycloisomerization of (Z)-2-en-4-yn-1-ols, is described. Cycloisomerization reactions are carried out at 25-100 °C in the presence of a very simple catalytic system, consisting of K2PdI4, under essentially neutral conditions. This new methodology is very versatile and can be applied to the synthesis of a variety of substituted furans, including particularly fragile, naturally occurring furans such as rosefuran. Efficient synthetic approaches for the regioselective synthesis of suitably substituted (Z)-2-en-4-yn-1-ols have been developed.
- Gabriele,Salerno,Lauria
-
p. 7687 - 7692
(2007/10/03)
-
- An efficient and general synthesis of furan-2-acetic esters by palladium-catalyzed oxidative carbonylation of (Z)-2-En-4-yn-l-ols
-
A variety of (Z)-2-en-4-yn-l-ols have been carbonylated under oxidative conditions to give substituted furan-2-acetic esters in good yields. The cyclization-alkoxycarbonylation process occurs in alcoholic media at 50-70 °C and under 100 atm pressure of a 9:1 mixture of carbon monoxide and air in the presence of catalytic amounts of PdI2 in conjunction with KI. The proposed reaction pathway involves the in situ isomerization of the initially formed (£)-2-[(alkoxycarbonyl)methylene]-2, 5-dihydrofuran species, which in some cases have been isolated and shown to be the intermediates.
- Gabriele, Bartolo,Salerno, Giuseppe,De Pascali, Francesca,Costa, Mirco,Chiusoli, Gian Paolo
-
p. 7693 - 7699
(2007/10/03)
-
- Gas-phase electrophilic aromatic substitution of electron-rich and electron-deficient aromatic compounds
-
The first step in gas-phase electrophilic aromatic substitution (EAS) reactions of alkyl carbenium ions with fluoro-, chloro- and bromo-benzene, furan, thiophene and pyrrole, has been investigated by using high-pressure, chemical-ionization and tandem mass spectrometry (MS/MS). Collisionally activated dissociation (CAD) and tandem mass spectrometry, MS/MS, have been utilized for ion-structure determination. The coexistence of σ and π complexes in these reactions is a means of rationalizing the results. It has been established that the extent of π-complex formation decreases with an increased capability of the aromatic to donate electron density. Semi-empirical computations indicate that as π-electron density within the aromatic moiety increases, the energy difference between the more stable σ complex and the π complex increases, which is also consistent with experimental observations. The extent of bonding between the alkyl group and the aromatic of certain π complexes is sufficiently weak that isomerization of the alkyl moiety takes place.
- Holman, Robert W.,Eary, Todd,Whittle, Ed,Gross, Michael L.
-
p. 2187 - 2193
(2007/10/03)
-
- Reactions of N-methyl-2-phenylindole with malondialdehyde and 4- hydroxyalkenals. Mechanistic aspects of the colorimetric assay of lipid peroxidation
-
Under specific acidic conditions, both malondialdehyde (1, MDA) and 4- hydroxynonenal (2, 4-HNE) react with N-methyl-2-phenylindole (3) to give the same chromophoric cyanine 4 with maximal absorbance at 586 nm. Under such conditions, the reaction of 3 with 4-HNE (2) as well as with alkanals yields a second chromophoric cyanine 10 with maximal absorbance at 505 nm. The influence of different acids, iron(III), and oxygen on the reaction of 3 with such aldehydes was studied in detail. Under anaerobic conditions, the acid- induced reaction of 4-HNE with 3 afforded three rapidly interconverting intermediates, 5-7. Their subsequent fragmentation to 4 and hexanal in the presence of iron(III) and oxygen is consistent with the tandem β- fragmentation of an indolyl radical cation. 1-Indolylalkenes were identified as essential intermediates in the acid-induced reaction of 3 with alkanals. A very mild iron(III)catalyzed fragmentation of these intermediates afforded the corresponding 3-formylindole 11 as the direct precursor of the 505 nm chromophore 10. Such reactions were markedly influenced by the nature of the acid. Contrary to the rapid chromogenic reaction of 4-HNE which was observed in the presence of methanesulfonic acid, the HCl-induced reaction of 4-HNE with 3 did not afford the 586 nm chromophore. Furthermore, hexanal did not yield the 505 nm chromophore 10 upon reaction with 3 in the presence of HCl, again in contrast with the rapid chromogenic reaction which was observed in the presence of methanesulfonic acid. Comparison of the reaction mixtures under the two assay conditions confirmed that the same intermediates were formed. We conclude that the nature of the acid plays a crucial role in the oxidative fragmentation of intermediates into chromophores, allowing the selective assay of MDA in the presence of 4-HNE, using HCl acidic conditions.
- Erdelmeier, Irene,Gerard-Monnier, Dominique,Yadan, Jean-Claude,Chaudiere, Jean
-
p. 1184 - 1194
(2007/10/03)
-
- Synthesis of (E)-4-Oxonon-2-enoic acid, a natural antibiotic produced by Streptomyces olivaceus
-
(E)-4-Oxonon-2-enoic acid (1), a natural antibiotic produced by Streptomyces otivaceus, has been conveniently prepared in three steps starting from furan.
- Ballini,Bosica
-
p. 673 - 674
(2007/10/03)
-
- Alkylation of Aldehyde (Arenesulfonyl)hydrazones with Trialkylboranes
-
(Arenesulfonyl)hydrazone derivatives of aryl aldehydes are readily alkylated by trialkylboranes in the presence of base to generate new organoboranes that may be converted to the corresponding substituted alkanes or alcohols depending upon the reaction conditions chosen. Both tosyl- and trisylhydrazone derivatives can be utilized in the reaction, which tolerates a variety of functional groups, making it a versatile alternative to both the Grignard and Suzuki-coupling reactions.
- Kabalka, George W.,Maddox, John T.,Bogas, Ekaterini,Kelley, Shane W.
-
p. 3688 - 3695
(2007/10/03)
-
- Epoxyoxoene fatty esters: key intermediates for the synthesis of long-chain pyrrole and furan fatty esters
-
The reaction of epoxyoxoene fatty esters, methyl (Z)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (1) and methyl (Z)-12,13-epoxy-9-oxo-(E)-10-octadecenoate (2), with glycine methyl ester in the presence of a basic resin was studied to establish if these compounds might be useful intermediates in the preparation of long-chain pyrrole fatty esters.Production of C18 pyrrole fatty esters and fragmentation products with the pyrrole ring were isolated and identified in the reaction.In addition, furanoid derivatives with analogous structures were also detected and identified.Formation of these last compounds was induced by the basic resin and the same compounds were also produced in a reaction mixture incubated in the absence of the amino acid.The results found in this study show that epoxyoxoene fatty esters 1 and 2 may be used in the preparation of both long-chain pyrrole and furan fatty acids.Although their existence in nature is as yet unclear, the mass spectra results obtained in this study provide the basis for detection and identification of this type of long-chain pyrrole and furan fatty acids by gas chromatography coupled with mass spectrometry.Keywords: Long-chain pyrrole fatty esters; Long-chain furanoid fatty acids; Carbonyl-amine reactions; Oxidized lipids/amino acids reactions; Lipid peroxidation products; Non-enzymatic browning reactions
- Hidalgo, Francisco J.,Zamora, Rosario
-
-
- HETEROCYCLIZATION OF β,γ-DICHLORO KETONES AS A METHOD FOR THE SYNTHESIS OF FURAN DERIVATIVES
-
Dichloro ketones obtained from acyl chlorides and allyl or β-methylallyl chloride undergo spontaneous cyclization to give 2-alkyl- and 2,4-dialkylfurans when they are heated; the intermediates in the case of 2,3-dichloropropene split out a molecule of hydrogen chloride to give 3,4-dichloro-2-butenones.
- Mamedov, E. J.,Ismailov, A. G.,Kozhushkov, S. I.,Zefirov, N. S.
-
p. 260 - 265
(2007/10/02)
-
- CHEMISTRY OF SYSTEMS OF THE ALLYLIC TYPE II. ACYLATION OF 3-BROMO- AND 2-METHYL-3-CHLORO-1-PROPENES
-
The acylation of 3-bromo- and 2-methyl-3-chloro-1-propenes under the conditions of the Kondakov-Krapivin reaction showed that the addition of acyl chlorides to these compounds takes place according to the Markovnikov rule with formation of the corresponding halogen-containing α-β-unsaturated ketones and alkyl(cycloalkyl)furans.
- Ibragimov, I. I.,Mamedov, E. I.,Ismailov, A. T.,Aliev, A. G.,Mekhtieva, Sh. Z.,et al.
-
p. 1425 - 1430
(2007/10/02)
-
- Synthesis and Characterisation of some 1,4,8,11,15,18,22,25-Octa-alkyl- and 1,4,8,11,15,18-Hexa-alkyl-22,25-bis(carboxypropyl)phthalocyanines
-
A series of 3,6-dialkylphthalonitriles and 3,6-bis(4,4,4-trimethoxybutyl)phthalonitrile have been prepared via Diels-Alder reactions of 2,5-disubstituted furans or thiophene 1,1-dioxides with fumaronitrile.The phthalonitriles were converted into the title phthalocyanines as metal-free and copper(II) derivatives.The macrocycles were characterised using 1H NMR and optical spectroscopy, and fastatom bombardment spectrometry.Certain examples exhibit discotic liquid crystal behaviour.
- McKeown, Neil B.,Chambrier, Isabelle,Cook, Michael J.
-
p. 1169 - 1177
(2007/10/02)
-
- APPLICATION OF FURAN OXIDATIONS IN SYNTHESIS: TOTAL SYNTHESIS OF (+/-)-COROLIC ACID
-
As a general synthesis approach to compounds containing the cis-trans allylhydroxy functionality ( subunit A), an appropriately substituted furan nucleus is oxidatively cleaved to provide an unsaturated 1,4-dicarbonyl moiety suitably disposed for further elaboration.The total synthesis of (+/-)-coriolic acid demonstrates the utility of the approach.
- Gunn, Bruce P.
-
p. 3061 - 3067
(2007/10/02)
-
- The Reduction of 2-Substituted Furan Derivatives with Lithium and Ammonia
-
The reduction of 1-(furan-2'-yl)nonan-1-one with lithium and ammonia in the presence of alcohols gave 1-(2',3'-dihydrofuran-2'-yl)nonan-1-one as the major product or a mixture of 1-(tetrahydrofuran-2'-yl)nonan-1-one and tridecane-1,5-diol depending on the conditions. 1-(Furan-2'-yl)nonyl acetate, 2-(1'-methoxynonyl)furan, 1-(furan-2'-yl)nonan-1-ol, 2-(1',1'-ethylenedioxynonyl)furan and 2-(pent-1'-enyl)furan have also been reduced both in the presence and absence of an alcohol.
- Massy-Westropp, Ralph A.,Warren, Richard F.O.
-
p. 1303 - 1311
(2007/10/02)
-
- 180. Some Novel Nematic Materials Bearing Two Lateral Nitrile Functions
-
More than fifty esters of 3-alkyl-6-hydroxy-1,2-benzenedicarbonitrile have been prepared.The new esters exhibit stable nematic phases of high negative dielectric anisotropy.The relationship between the clearing points of the esters and the various ring they incorporate is the same as that normally observed for nematic materials of positive dielectric anisotropy.
- Kelly, Stephen M.,Huynh-Ba, Tuong
-
p. 1850 - 1859
(2007/10/02)
-
- 3. 2. 1.
-
8-Oxabicyclo left bracket 3. 2. 1 right bracket octan-3-one derivatives serve as excellent models that elucidate factors controlling the reactivities and selectivities in the Baeyer-Villiger oxidation. The regioselectivity of the oxidation with trifluoroperacetic acid is markedly affected by the electronic properties of substituents at position alpha or beta to the carbonyl function. Remote effects of the gamma -substituents are also of significance. This study has disclosed yet unrecognized through-bond electronic influence and regioselection based on chiral orientation of hydroxyl group in the transient tetrahedral intermediate.
- Noyori,Sato,Kobayashi
-
p. 2661 - 2679
(2007/10/02)
-