- Diene conformation in the naturally occurring tricarboxylic acid, telfairic acid, by Raman spectroscopy
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The conformational geometry of the two C{double bond, short}C bonds in a naturally occurring dienetricarboxylic acid, telfairic acid, isolated from Xylaria telfairii, has been determined by Raman spectroscopy. This application of analytical Raman spectroscopy is important because infrared, UV and NMR spectroscopic techniques have failed to provide sufficient information for the determination of the diene geometry. Several specially synthesised model dienecarboxylic acids with known diene conformations were used to calibrate the Raman data. The natural extract from X. telfairii was shown to be a mixture of both cis (Z) and trans (E) forms whereas the purified extract was predominantly the trans isomer. Raman data also suggest that the established method for the preparation of a trans-trans sorbic acid is open to debate. Further applications of the Raman technique for the determination of diene conformation of fungal metabolite extracts are proposed.
- Edwards, Howell G.M.,Edwards, Raymond L.,Hartley, Melanie J.,Quinn, Michael
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- Palladium η3-allyl complex with sorbic acid: Kinetics and mechanism of protodemetalation in aqueous solutions
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The allyl complex di-μ-chloro-bis[(1,2,3-η)-1-carboxy-3-(1- hydroxyethyl)allyl]dipalladium (which is a hydroxyl-containing palladium η3-allyl complex based on sorbic acid) has been synthesized from trans,trans-2,4-hexadienic (sorbic) acid and Na2PdCl4 in an aqueous solution. The complex has been isolated from the reaction solution and has been characterized by IR, 1H NMR, and 13C NMR spectroscopy. Its composition has been determined by elemental analysis. The protodemetalation kinetics of the complex in aqueous solutions has been studied. The rate of this reaction obeys a second-order equation, first-order with respect to each reactant. A reaction mechanism has been derived from protodemetalation kinetics and data characterizing the state of the reactants. Nauka/Interperiodica 2006.
- Surovtseva,Orlov,Morozova,Krylov,Belov
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- Chiral Pyridinium Phosphoramide as a Dual Br?nsted Acid Catalyst for Enantioselective Diels-Alder Reaction
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Chiral pyridinium phosphoramide 1·HX was designed to be a new class of chiral Br?nsted acid catalyst in which both the pyridinium proton and the adjacent imide-like proton activated by the electron-withdrawing pyridinium moiety could work cooperatively as strong dual proton donors. The potential of 1·HX was shown in the enantioselective Diels-Alder reactions of 1-amino dienes with various dienophiles including N-unsubstituted maleimide, which has yet to be successfully used in an asymmetric Diels-Alder reaction.
- Nishikawa, Yasuhiro,Nakano, Saki,Tahira, Yuu,Terazawa, Kanako,Yamazaki, Ken,Kitamura, Chitoshi,Hara, Osamu
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- Lewis acid-mediated carboxylation of aryl- and allylsilanes with carbon dioxide
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Aryl- and allylsilanes are carboxylated with CO2 with the aid of aluminum-based Lewis acids, to give aromatic and β, γ-unsaturated carboxylic acids in fair to good yields, respectively. Formation of the former is rationalized by an aromatic electrophilic substitution by CO2 activated by the Lewis acid, while the latter a nucleophilic addition of in situ-generated allylaluminum species to CO2.
- Hattori, Tetsutaro,Suzuki, Yutaka,Miyano, Sotaro
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- The Mechanism of Dehydrating Bimodules in trans-Acyltransferase Polyketide Biosynthesis: A Showcase Study on Hepatoprotective Hangtaimycin
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A bioassay-guided fractionation led to the isolation of hangtaimycin (HTM) from Streptomyces spectabilis CCTCC M2017417 and the discovery of its hepatoprotective properties. Structure elucidation by NMR suggested the need for a structural revision. A putative HTM degradation product was also isolated and its structure was confirmed by total synthesis. The biosynthetic gene cluster was identified and resembles a hybrid trans-AT PKS/NRPS biosynthetic machinery whose first PKS enzyme contains an internal dehydrating bimodule, which is usually found split in other trans-AT PKSs. The mechanisms of such dehydrating bimodules have often been proposed, but have never been deeply investigated. Here we present in vivo mutations and in vitro enzymatic experiments that give first and detailed mechanistic insights into catalysis by dehydrating bimodules.
- Deng, Zixin,Dickschat, Jeroen S.,Dong, Yulu,Lu, Junlei,Luo, Minghe,Qi, Miaomiao,Shen, Kun,Sun, Guo,Sun, Yuhui,Tang, Lingjie,Xiang, Jin,Xu, Houchao,Yin, Zhiyong
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- Synthesis of 3,6-dihydro-2H-pyran-2-ones via cationic palladium(II) complex-catalyzed tandem [2+2] cycloaddition-allylic rearrangement of ketene with α,β-unsaturated aldehydes and ketones
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Treatment of ketene with α,β-unsaturated aldehydes and ketones in the presence of [Pd(dppb)(PhCN)2](BF4)2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon center at the β-position. A zwitterion generated by heterolytic cleavage of the C(4)-O bond of the 4-vinyloxetan-2-one is considered to be an intermediate in the allylic rearrangement. Ethanolysis of 3,6-dihydro-6-methyl-2H-pyran-2-one under acid conditions, followed by saponification of the resulting ethyl 2,4-hexadienoate (ethyl sorbate), gives sorbic acid in 90% yield.
- Hattori, Tetsutaro,Suzuki, Yutaka,Ito, Yuuichi,Hotta, Daido,Miyano, Sotaro
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- Studies toward the synthesis of (-)-zampanolide: preparation of N-acyl hemiaminal model systems.
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[structure: see text] Synthesis of N-acyl hemiaminal model systems related to the side chain of the antitumor natural product zampanolide is reported. Key steps involve oxidative decarboxylation of N-acyl-alpha-amino acid intermediates, followed by ytterb
- Troast, Dawn M,Porco Jr., John A
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- Direct conversion of polyconjugated compounds into their corresponding carboxylic acids by Acetobacter aceti
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The conversion of polyconjugated aldehydes or alcohols into their corresponding acids was carried out using Acetobacter aceti. The analytical results were compared with those of the acids chemically obtained using a Horner-Wittig reaction.
- Pini, Elena,Bertacche, Vittorio,Molinari, Francesco,Romano, Diego,Gandolfi, Raffaella
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- NEW CONVERSIONS OF SUBSTITUTED VINYLCYCLOPROPANES UNDER THE EFFECT OF COMPLEXES OF RHODIUM AND PALLADIUM
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Methods have been developed for the synthesis of the dimethyl ester of 1-carboxysorbic acid, 2-methyl-3-acetyl-5-vinyl- and 2-methyl-3-ethylcarboxy-5-vinyldihydrofurans by isomerization, respectively, of 1,1-dimethylcarboxy-2-vinyl-, 1,1-diacetyl-2-vinyl-, and 1-acetyl-1-ethylcarboxy-2-vinylcyclopropanes under the effect of Rh- and Pd-containing catalysts promoted with AcOH or CF3COOH.
- Dzhemilev, U. M.,Khusnutdinov, R. I.,Shchadneva, N. A.,Tolstikov, G. A.
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- SORBINSAEURE AUS PIPERYLEN UND CO2 DURCH C-C-VERKNUEPFUNG AN NICKEL(0)
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Piperylene reacts with (Lig)Ni0 compounds in the presence of CO2 to give isomeric nickela complexes IV.The mixture of the isomers reacts with maleic anhydride to produce sorbic acid directly.
- Hoberg, Heinz,Schaefer, Dietmar
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- Ether-functionalized ionic liquids for nonaqueous biocatalysis: Effect of different cation cores
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Ether-functionalized ionic liquids (ILs) usually have low viscosities, and can be designed to be compatible with enzymes. However, there is a lack of understanding of the effect of different ether-functionalized structures on the enzyme activity. We systematically evaluated new ether-functionalized ILs carrying different cation cores (pairing with Tf2N? anions) in two Novozym 435-catalyzed reactions: (1) the transesterification of ethyl sorbate with 1-propanol at 50 °C; (2) the ring-opening polymerization (ROP) of ε-caprolactone at 70 °C. The lipase showed different activities: in the first reaction, [CH3OCH2CH2-Et3N][Tf2N] and [CH3OCH2CH2-Py][Tf2N] gave the highest reaction rates; in the second reaction, [CH3OCH2CH2-PBu3][Tf2N] produced the highest molecular mass (Mw up to 25,400 Da). The lipase's thermal stability in [CH3OCH2CH2-Et3N][Tf2N] was found much higher than that in t-butanol. The fluorescence spectra of free lipase (excited at 280 nm) in these ILs reveal that the wavelength of the maximum emission peak occurred at 314 nm for both [CH3OCH2CH2PBu3][Tf2N] and [CH3OCH2CH2PEt3][Tf2N], which matched closely with that (313 nm) in aqueous phosphate buffer (pH 7.5, 20 mM), while other ether-functionalized ILs led to various degrees of red shifts. In summary, the lipase activity is not only dependent on the IL structure, but also on the substrate and other reaction conditions.
- Zhao, Hua,Kanpadee, Naphatsawan,Jindarat, Chanida
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- Enantioselective and Diastereodivergent Synthesis of Spiroindolenines via Chiral Phosphoric Acid-Catalyzed Cycloaddition
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A diastereodivergent and enantioselective synthesis of chiral spirocyclohexyl-indolenines with four contiguous stereogenic centers is achieved by a chiral phosphoric acid-catalyzed cycloaddition of 2-susbtituted 3-indolylmethanols with 1,3-dienecarbamates. Modular access to two different diastereoisomers with high enantioselectivities was obtained by careful choice of reaction conditions. Their functional group manipulation provides an efficient access to enantioenriched spirocyclohexyl-indolines and -oxindoles. The origins of this stereocontrol have been identified using DFT calculations, which reveal an unexpected mechanism compared to our previous work dealing with enecarbamates.
- Gandon, Vincent,Masson, Géraldine,Mati?i?, Mateja,Neuville, Luc,Van Elslande, Elsa,Varlet, Thomas
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supporting information
p. 11611 - 11619
(2021/08/16)
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- Preparation method of gamma-substituted hexadienoic acid
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The invention relates to a preparation method of gamma-substituted hexadienoic acid. The method is characterized by comprising the following steps: (1) at -10-40 DEG C, adding a solvent, a catalyst and a catalytic assistant into a reaction vessel, stirring, introducing oxygen, adding 1-(2-furyl)-1-alkyl methanol, controlling the molar ratio of the catalyst to the catalytic assistant to the 1-(2-furyl)-1-alkyl methanol at 0.0001-5:0.0001-3:100, reacting at 0-200 DEG C under 0.1-20 MPa for 1-74 h, wherein the solvent is a mixed solution composed of a water phase and an organic phase according toa volume ratio of 1:0.01-3, the water phase is a phosphate acidic solution, the organic phase is a reaction inert solvent, the catalyst is a palladium compound, and the catalytic assistant is an amine or phosphine compound; and (2) cooling the reaction vessel to room temperature, adding an organic solvent, extracting, and carrying out reduced pressure distillation on the organic phase. The methodhas the advantages that the defect of technical economy in an existing synthesis route is overcome, the technological process is simplified, consumption and emission are reduced, energy consumption and cost are reduced, and the method is suitable for industrial production for increasing productivity.
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Paragraph 0019
(2021/01/20)
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- An Efficient Aerobic Oxidation Protocol of Aldehydes to Carboxylic Acids in Water Catalyzed by an Inorganic-Ligand-Supported Copper Catalyst
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A method for the aerobic oxidation of aldehydes to carboxylic acids in water by using an inorganic-ligand-supported copper catalyst was developed. This method was performed with the use of atmospheric oxygen as the sole oxidant under extremely mild aqueous conditions, and furthermore, a wide range of aldehydes with various functional groups were tolerated. The copper catalyst could be recycled and used in successive reactions at least six times without any appreciable degradation in performance. This method is operationally simple and avoids the use of high-costing, toxic, air/moisture-sensitive, and commercially unavailable organic ligands. The generality of this method gives it potential to be used on the industrial scale.
- Yu, Han,Ru, Shi,Zhai, Yongyan,Dai, Guoyong,Han, Sheng,Wei, Yongge
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p. 1253 - 1257
(2018/02/16)
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- A colourful azulene-based protecting group for carboxylic acids
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An intensely blue-coloured protecting group for carboxylic acids has been developed. The protecting group is introduced through a Steglich esterification that couples 6-(2-hydroxyethyl)azulene (AzulE) and the carboxylic acid substrate. Deprotection is effected under basic conditions by the addition of the amidine base DBU, whereupon cleavage occurs, accompanied by a colour change. A two-step deprotection methodology comprising activation with oxalyl chloride and deprotection with a very mild base was developed for use with base-sensitive substrates. The AzulE esters were found to be compatible with other commonly employed protecting groups – silyl ethers, MOM acetals – by studying their orthogonal and concomitant deprotections. The stability of the new protecting group towards various synthetic processes – oxidation, reduction, cross-coupling, olefination and treatment with base – provided the basis of a versatility profile. This indicated that AzulE esters are sensitive to strongly oxidising and basic agents while being compatible with reducing conditions and selected other reactions. The convenience of a highly coloured protecting group for tracking material (and avoiding loss of compound) through laboratory processes warrants further investigation of this and/or related species.
- Bevan, Thomas W.,Francis-Taylor, James,Wong, Helena,Northcote, Peter T.,Harvey, Joanne E.
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supporting information
p. 2942 - 2955
(2018/05/16)
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- An Efficient Iron(III)-Catalyzed Aerobic Oxidation of Aldehydes in Water for the Green Preparation of Carboxylic Acids
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The first example of a heterogeneous iron(III)-catalyzed aerobic oxidation of aldehydes in water was developed. This method utilizes 1 atmosphere of oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification. Its operational simplicity, gram-scale oxidation, and the ability to successively reuse the catalyst, make this new methodology environmentally benign and cost effective. The generality of this methodology gives it the potential to be used on an industrial scale.
- Yu, Han,Ru, Shi,Dai, Guoyong,Zhai, Yongyan,Lin, Hualin,Han, Sheng,Wei, Yongge
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p. 3867 - 3871
(2017/03/27)
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- Enantioselective Synthesis of N?H-Free 1,5-Benzothiazepines
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An enantioselective sulfa-Michael-cyclization reaction was developed for the synthesis of 1,5-benzothiazepines with versatile pharmacological activities. The reaction between 2-aminothiophenol and α,β-unsaturated pyrazoleamides gave direct access to N?H-free 1,5-benzothiazepines in the presence of a chiral N,N′-dioxide/Yb(OTf)3complex. Excellent enantioselectivities (up to 96 % ee) and high yields (up to 99 %) were obtained for a broad range of substrates under mild reaction conditions. This method provided a facile approach to the antidepressant drug (R)-(?)-Thiazesim.
- Wang, Guojin,Tang, Yu,Zhang, Yu,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 554 - 557
(2017/01/18)
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- Solar lab and pilot scale photo-oxidation of ethylparaben using H2O2 and TiO2 in aqueous solutions
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Ethylparaben (Eth-PB) is one of the most used parabens for preservation of many personal care products and food. However, a number of scientific studies have indicated that this compound could interfere with the endocrine or hormonal system of different living beings, which along with data about its presence in different water bodies generates the necessity of seeking alternatives to minimize the potential negative effect of this situation. In this way, removal of Eth-PB using heterogeneous photocatalysis with TiO2, hydrogen peroxide and light radiation (solar spectrum: wavelength >290 nm) was assessed, considering the individual effects of different operational parameters like the catalyst and H2O2 dosages, the pH and the pollutant initial concentration. According to this, conditions that, under the experimental range, promote a higher paraben elimination were established. Tests were carried out at lab-scale using a photo-simulator equipped with a Xenon lamp, and at pilot scale (volume treated ～100 L) using a compound parabolic collector and direct solar light radiation. In both cases, more than a 80% of substrate elimination was reached in less than 6 h of reaction, demonstrating the effectiveness of the photocatalytic system to remove this kind of compounds. Additionally, a significant reduction of the total organic carbon present in the solutions, and an increment of the biodegradability of the samples were appreciated. Finally, some of the by-products generated during the contaminant removal were identified.
- Zú?iga-Benítez, Henry,Pe?uela, Gustavo A.
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- DMF-mediated deprotection of bulky silyl esters under neutral and fluoride-free conditions
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Bulky TBDPS and TIPS carboxylic esters were efficiently cleaved by a green and mild protocol using only DMF-H2O (20:1) at 70 °C. The neutral conditions tolerate various common acid- and base-labile functionalities, including alkyl and aryl silyl ethers.
- Chen, Bo,Sun, Hui-Xia,Qin, Jian-Feng,Wang, Bing
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p. 253 - 255
(2016/01/12)
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- Studies on [2?+?3] cycloaddition reaction of nitrile oxides to linear dipolarophiles bearing multiple double bonds
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Abstract: Site selectivity, regioselectivity, and stereoselectivity of [2?+?3] cycloaddition of benzonitrile oxides to polyunsaturated esters were examined. Site selectivity was correlated with electron charges of unsaturated carbon atoms. Structure of the products has been established by an extensive application of 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry. Graphical abstract: [Figure not available: see fulltext.]
- Gucma, Miros?aw,Go??biewski, W. Marek,Michalczyk, Alicja Katarzyna
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p. 1809 - 1818
(2016/09/28)
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- Acrylate formation from CO2 and ethylene: catalysis with palladium and mechanistic insight
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We report the first catalyst based on palladium for the reaction of CO2, alkene and a base to form sodium acrylate and derivatives. A mechanism similar to a previously reported Ni(0)-catalyst is proposed based on stoichiometric in situ NMR experiments, isolated intermediates and a parent palladalactone. Our palladium catalyst was applied to the coupling of CO2 with conjugated alkenes.
- Stieber, S. Chantal E.,Huguet, Núria,Kageyama, Takeharu,Jevtovikj, Ivana,Ariyananda, Piyal,Gordillo, Alvaro,Schunk, Stephan A.,Rominger, Frank,Hofmann, Peter,Limbach, Michael
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supporting information
p. 10907 - 10909
(2015/06/30)
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- Formal ring-opening/cross-coupling reactions of 2-pyrones: Iron-catalyzed entry into stereodefined dienyl carboxylates
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Open access: Despite the exceptional level of sophistication in cross-coupling chemistry, reactions of substrates that incorporate the leaving group as an integral part into a heterocyclic scaffold are scarce. The title reaction outlines the utility of this reaction format (see scheme; acac=acetylacetonate), provides a convenient entry into stereodefined diene carboxylates, and adds a new chapter to the field of iron catalysis. Copyright
- Sun, Chang-Liang,Fuerstner, Alois
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supporting information
p. 13071 - 13075
(2014/01/06)
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- One-flask tethered ring closing metathesis-electrocyclic ring opening for the highly stereoselective synthesis of conjugated Z/E-dienes
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A one-flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base-mediated ring opening gives 2Z,4E-configured dienoic acids in high yields and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised. Ring closing metathesis (RCM) of butenoates derived from allylic alcohols can be combined with base-induced ring opening in a one-flask sequence. In this way, dienoic acids become accessible in an operationally simple procedure in very high yields and excellent stereoselectivities, with the tether remaining in the product as a valuable functional group for further transformations. Copyright
- Schmidt, Bernd,Kunz, Oliver
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p. 1008 - 1018
(2012/03/27)
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- PRODUCTION OF 2,4-HEXADIENOIC ACID AND 1,3-PENTADIENE FROM 6-METHYL-5,6-DIHYDRO-2-PYRONE
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Described is a method of making sorbic acid, pentadiene, or 3-penten-2-one. The method includes partially hydrogenating 4-hydroxy-6-methyl-2-pyrone (HMP) to yield 5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one (4-DHMMP). Then, if 3-penten-2-one is desired, thermally decomposing the 4-DHMMP to yield 3-penten-2-one. If sorbic acid or pentadiene are desired, the 4-DHMMP is hydrogenated to yield 4-hydroxy-6-methyltetrahydro-2-pyrone (4-HMTHP). The 4-HMTHP is then dehydrated by contacting it with a solid acid catalyst to yield parasorbic acid (PSA). The PSA can then be ring-opened by contacting it with a solid acid catalyst. The reaction conditions of the ring-opening reaction can be controlled to yield sorbic acid and/or pentadiene.
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Page/Page column 7
(2012/05/20)
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- New eutectic ionic liquids for lipase activation and enzymatic preparation of biodiesel
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The enzymatic preparation of biodiesel has been hampered by the lack of suitable solvents with desirable properties such as high lipase compatibility, low cost, low viscosity, high biodegradability, and ease of product separation. Recent interest in using ionic liquids (ILs) as advanced reaction media has led to fast reaction rates and high yields in the enzymatic synthesis of biodiesel. However, conventional (i.e., cation-anion paired) ILs based on imidazolium and other quaternary ammonium salts remain too expensive for wide application at industrial scales. In this study, we report on newly-synthesized eutectic ILs derived from choline acetate or choline chloride coupled with biocompatible hydrogen-bond donors, such as glycerol. These eutectic solvents have favorable properties including low viscosity, high biodegradability, and excellent compatibility with Novozym 435, a commercial immobilized Candida antarctica lipase B. Furthermore, in a model biodiesel synthesis system, we demonstrate high reaction rates for the enzymatic transesterification of Miglyol oil 812 with methanol, catalyzed by Novozym 435 in choline acetate/glycerol (1:1.5 molar ratio). The high conversion (97%) of the triglyceride obtained within 3 h, under optimal conditions, suggests that these novel eutectic solvents warrant further exploration as potential media in the enzymatic production of biodiesel.
- Zhao, Hua,Baker, Gary A.,Holmes, Shaletha
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supporting information; experimental part
p. 1908 - 1916
(2011/04/23)
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- Method for regio- and stereoselective synthesis of (E)-Β,γ- unsaturated acids from aldehydes under solvent-free conditions
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Synthesis of (E)-β,-γunsaturated acids from aldehydes with malonic acid has been explored under solvent-free conditions. The modified Knoevenagel condensation reaction with N-methyl morpholine (NMM) as catalyst exhibits highly β,-γ regioselectivity and exclusively E-stereoselectivity. A mechanism accounting for both regio- and stereoselectivity has been proposed and preliminarily studied. Copyright Taylor & Francis Group, LLC.
- Zhang, Shi-Jie,Hu, Wei-Xiao
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experimental part
p. 3093 - 3100
(2010/12/19)
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- Kinetic and chemical characterization of aldehyde oxidation by fungal aryl-alcohol oxidase
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Fungal AAO (aryl-alcohol oxidase) provides H2O2 for lignin biodegradation. AAO is active on benzyl alcohols that are oxidized to aldehydes. However, during oxidation of some alcohols, AAO forms more than a stoichiometric number of H2O2 molecules with respect to the amount of aldehyde detected due to a double reaction that involves aryl-aldehyde oxidase activity. The latter reactionwas investigated using different benzylic aldehydes, whose oxidation to acids was demonstrated by GC-MS. The steady- and presteady state kinetic constants, together with the chromatographic results, revealed that the presence of substrate electron-withdrawing or electron-donating substituents had a strong influence on activity; the highest activity was with p-nitrobenzaldehyde and halogenated aldehydes and the lowest with methoxylated aldehydes. Moreover, activity was correlated to the aldehyde hydration rates estimated by 1H-NMR. These findings, together with the absence in the AAO active site of a residue able to drive oxidation via an aldehyde thiohemiacetal, suggested that oxidation mainly proceeds via the gem-diol species. The reaction mechanism (with a solvent isotope effect, 2H2O kred, of approx. 1.5)would be analogous to that described for alcohols, the reductive half-reaction involving concerted hydride transfer from the a-carbon and proton abstraction from one of the gem-diol hydroxy groups by a base. The existence of two steps of opposite polar requirements (hydration and hydride transfer) explains some aspects of aldehyde oxidation by AAO. Site-directed mutagenesis identified two histidine residues strongly involved in gem-diol oxidation and, unexpectedly, suggested that an active-site tyrosine residue could facilitate the oxidation of some aldehydes that show no detectable hydration. Double alcohol and aldehyde oxidase activities of AAO would contribute to H2O2 supply by the enzyme. The Authors Journal compilation
- Ferreira, Patricia,Hernandez-Ortega, Aitor,Herguedas, Beatriz,Rencoret, Jorge,Gutierrez, Ana,Martinez, Maria Jesus,Jimenez-Barbero, Jesus,Medina, Milagros,Martinez, Angel T.
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scheme or table
p. 585 - 593
(2011/02/24)
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- Solvent-modulated chemoselective deprotections of trialkylsilyl esters and chemoselective esterifications
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A series of trialkylsilyl esters were deprotected or transesterificated into their corresponding carboxylic acids or methyl esters under a catalytic amount of CBr4 in alcohol reaction system. This method enables to desilylate secondary sp3-carbon, sp2-carbon, sp-carbon and aryl tethered trialkylsilyl esters to carboxylic acids, whereas primary sp 3-carbon tethered trialkylsilyl esters were further converted into their methyl esters under CBr4/MeOH reaction conditions. The highly chemoselective deprotections can be modulated and achieved by the introduced protecting trialkylsilyl groups and the used alcohols such as MeOH and EtOH under this photochemically-induced reaction conditions.
- Lee, Adam Shih-Yuan,Su, Feng-Yih
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p. 6305 - 6309
(2007/10/03)
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- Asymmetric total synthesis of sperabillins B and D via lithium amide conjugate addition
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Diastereoselective conjugate addition of homochiral lithium (R)-N-allyl-N-α-methylbenzylamide to methyl (2E,5E)-hepatadienoate, followed by protecting group manipulation and subsequent iodocyclocarbamation allows a concise route to the core fragment, methyl (3R,5R,6R)-3,6-diamino-5- hydroxyheptanoate, of sperabillins B and D. Differentiation between the C-3 and C-6 primary amino groups of this core amino acid was readily achieved by treatment with acetone, giving the 5,6-isopropylidene and C-3-imine protected diamine, with subsequent regioselective acylation of the C-6-nitrogen facilitating the total synthesis of sperabillin D in 10.8% overall yield, and the first asymmetric synthesis of sperabillin B in 5.8% overall yield.
- Davies, Stephen G.,Haggitt, Jane R.,Ichihara, Osamu,Kelly, Richard J.,Leech, Michael A.,Mortimer, Anne J. Price,Roberts, Paul M.,Smith, Andrew D.
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p. 2630 - 2649
(2007/10/03)
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- Processes for producing polyesters and producing sorbic acid
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The invented process for producing a polyester supplies a crotonaldehyde with a purity of 95% by weight or more to a reaction system in the reaction of ketene with crotonaldehyde. In this process, unreacted crotonaldehyde may be recovered from a reaction mixture obtained by the reaction of ketene with crotonaldehyde and may be recycled to the reaction system. The αvinylcrotonaldehyde content of the crotonaldehyde to be supplied to the reaction system is, for example, less than 0.5% by weight, and the paraldehyde content of the crotonaldehyde to be supplied to the reaction system is, for example, less than 5% by weight. By decomposing the above-prepared polyester with, for example, hydrochloric acid, a sorbic acid having a satisfactory hue can be efficiently obtained.
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- Process for the preparation of sorbic acid or salts thereof
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The invented process produces sorbic acid or its salt through the decomposition of a polyester obtained from ketene and aldehyde, and includes the step of treating a solution containing-sorbic acid or its salt with a chemically activated carbon, which sorbic acid or its salt is produced by the decomposition of the polyester. The treatment with activated carbon is performed, for example, at pH ranging from 5.8 to 7.5 at temperatures ranging from 30° C. to 80° C. The invented process can efficiently remove colored substances and can easily yield a high quality sorbic acid having a satisfactory hue in a high yield.
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- Total syntheses of (+)-zampanolide and (+)-dactylolide exploiting a unified strategy
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The first total syntheses of (+)-zampanolide (1) and (+)-dactylolide (2), members of a new class of tumor cell growth inhibitory macrolides, have been achieved. Key features of the unified synthetic scheme included the stereocontrolled construction of the cis-2,6-disubstituted tetrahydropyran via a modified Petasis-Ferrier rearrangement, a highly convergent assembly of the macrocyclic domain, and, in the case of zampanolide, a Curtius rearrangement/acylation tactic to install the N-acyl hemiaminal. The complete relative and absolute stereochemistries for both (+)-zampanolide and (+)-dactylolide were also assigned, albeit tentatively in the case of (+)-zampanolide (1).
- Smith III, Amos B.,Safonov, Igor G.,Corbett, R. Michael
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p. 11102 - 11113
(2007/10/03)
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- Process for producing sorbic acid
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A process produces sorbic acid by hydrolyzing a polyester with an aqueous hydrochloric acid solution having a concentration of 15% by weight or less under the application of pressure or at a temperature of 100° C. or higher, which polyester is obtained by reaction between crotonaldehyde and ketene. In this process, the polyester may be hydrolyzed with a 3 to 10% by weight aqueous hydrochloric acid solution at a temperature of from 115° C. to 140° C. A reaction mixture after hydrolysis of the polyester may be subjected to solid-liquid separation and the resulting filtrate may be recycled and reused in the hydrolysis reaction of the polyester. This process can significantly reduce the amount of tar formed during decomposition of the polyester, can produce sorbic acid in a high yield, and can reduce the load on the treatment of waste filtrates formed during purification operation.
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- Process for the preparation of sorbic acid
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The invented process produces sorbic acid by hydrolysis of a polyester in the presence of an acid, which polyester is obtained from ketene and crotonaldehyde. The process includes the step of subjecting a decomposition reaction mixture of the polyester to solid-liquid separation at temperatures ranging from 30° C. to 60° C. to yield sorbic acid as a solid. The process may further include the step of rinsing the sorbic acid obtained by solid-liquid separation with an aqueous solution containing sorbic acid, which aqueous solution is formed in a purification process of sorbic acid subsequent to the solid-liquid separation.The invented process can easily and efficiently remove tar substances by-produced in the reaction and can mitigate loads on a purification process.
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- Process for the preparation of sorbic acid
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The invented process produces sorbic acid. The process includes the steps of adding a crude sorbic acid to a hot water having a temperature exceeding 100° C., which crude sorbic acid is obtained by the decomposition of a polyester formed through a reaction of ketene with crotonaldehyde, and performing at least one treatment selected from (A) a hot water extraction treatment for extracting sorbic acid with the hot water, and (B) a treatment with an activated carbon in the hot water. The temperature of the hot water is, for example, 120° C. or lower. The amount of sorbic acid to be treated is, for example, equal to or less than the saturated dissolution amount of sorbic acid with respect to the hot water at a treating temperature. The invented process can easily and efficiently remove tar substances and other impurities by-produced in the decomposition of the polyester and can produce a highly purified sorbic acid with a high productivity.
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- Process for producing sorbic acid or salts thereof
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A process produces sorbic acid or its salt and includes the step of retaining a slurry or solution containing sorbic acid or its salt while holding an oxygen concentration of a gaseous phase at 4% by volume or less, the gaseous phase being in contact with the slurry or solution containing sorbic acid or its salt. In the process, the oxygen concentration of the gaseous phase may be held at 4% by volume or less while introducing an inert gas into a gaseous phase of a reservoir holding the slurry or solution and/or of a conduit adjacent to the reservoir. Such an inert gases includes, for example, nitrogen gas. The oxygen concentration of the gaseous phase is preferably held at 1% by volume or less. The process can prevent the formation of new color-inducing substances in a purification operation of sorbic acid or its salt, and the obtained sorbic acid or its salt has a minimized degree of coloring and a minimized deterioration of hue over time.
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- Process for producing sorbic acid
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A process produces sorbic acid by hydrolyzing a polyester with an aqueous hydrochloric acid solution having a concentration of 15% by weight or less under the application of pressure or at a temperature of 100°C or higher, which polyester is obtained by reaction between crotonaldehyde and ketene. In this process, the polyester may be hydrolyzed with a 3 to 10% by weight aqueous hydrochloric acid solution at a temperature of from 115°C to 140°C. A reaction mixture after hydrolysis of the polyester may be subjected to solid-liquid separation and the resulting filtrate may be recycled and reused in the hydrolysis reaction of the polyester. This process can significantly reduce the amount of tar formed during decomposition of the polyester, can produce sorbic acid in a high yield, and can reduce the load on the treatment of waste filtrates formed during purification operation.
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- Process for the preparation of unsaturated carboxylic acids
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A process for the manufacture of an unsaturated carboxylic acid or salt thereof comprising oxidising the corresponding unsaturated aldehyde with an oxidising agent selected from alkali metal hypohalites, hypohalous acids, peroxides, pyridine N-oxide or peracids in the presence of a transition metal oxide or hydroxide catalyst.
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- A simple and highly efficient deprotecting method for methoxymethyl and methoxyethoxymethyl ethers and methoxyethoxymethyl esters
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A series of methoxyethoxymethyl (MEM)- and methoxymethyl (MOM)-ethers and MEM-esters were hydrolyzed to their corresponding alcohols and carboxylic acids by a catalytic amount of CBr4 (10%) in iPrOH under refluxing reaction condition. The chemoselective hydrolysis between R3Si- and MEM-protected alcohols can be achieved by using different steric bulkness solvents such as MeOH or iPrOH.
- Shih-Yuan Lee, Adam,Hu, Yi-Jung,Chu, Shu-Fang
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p. 2121 - 2126
(2007/10/03)
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- Morpholinones as light stabilizers
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The invention relates to new compounds containing 1-8 active groups of the type 3,3,6,6-polysubstituted 2-morpholinone and having the formula F(A'-Z)m-X(F),wherein m is a number from 1 to 8; X is an organic anchor group of valency m and in case that m is not 1, X may also be a direct bond, SO2, P or PO; A' is a monovalent group of the formula E containing one linking group; Z is a direct bond, -O-, -S-, -SO-, -SO2- or -NR'14-; provided that Z is -O-, -S-, -SO-, -SO2- or -NR'14- if m is 1 and the linking group in formula E is G3 or G5; G1 is hydrogen; C1-C18alkyl; C2-C18alkyl substituted by OH and/or phenyl; oxyl; OH; C2-C12cyanoalkyl; C2-C12cyanoalkoxy; C1-C18alkoxy; C5-C12cycloalkoxy; C3-C8alkenyl; C3-C8alkynyl; C3-C8alkenyloxy; C7-C12phenylalkyl; C7-C12phenylalkyl substituted by hydroxy, C1-C4alkyl and/or C1-C4alkoxy; C7-C15phenylalkoxy; C7-C15phenylalkoxy, which is substituted by C1-C4alkyl and/or C1-C4alkoxy; or G1 is C1-C8alkanoyl; C3-C5alkenoyl; C1-C18alkanoyloxy; C3-C8epoxyalkyl; or G1 is the linking group -R10-; G2 and G4 are, independently of one another, C1-C18alkyl, C5-C12cycloalkenyl, C5-C12cycloalkyl, or an oligocyclic hydrocarbon residue of 6-12 carbon atoms; G3 is as defined for G2 or is C1-C8hydroxyalkyl; or G2 and G3 together are (CH2)e, where e is a number from 4 to 11; or G5 is the linking group -R5-; G5 is as defined for G4 or is C1-C8hydroxyalkyl; or G4 and G5 together are (CH2)e, where e is number from 4 to 11; or G5 is the linking group -R5-; G6 is as defined for G4 or is hydrogen; or G6 is the linking group, which is a direct bond or -R5-; and other residues are as defined in claim 1. The new compounds are effective as stabilizers for organic material, especially coatings, against harmful effects of light, oxygen and/or heat.
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- Cationic palladium(II) complex-catalyzed [2 + 2] cycloaddition and tandem cycloaddition-allylic rearrangement of ketene with aldehydes: An improved synthesis of sorbic acid
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Cationic palladium(II) complexes [PdL2(PhCN)2](BF4)2 efficiently catalyze the [2 + 2] cycloaddition of ketene with aldehydes to give the corresponding oxetan-2-ones, among which 4-vinyl-substituted ones are further isomerized under the conditions to give 3,6-dihydro-2H-pyran-2-ones in good yields.
- Hattori, Tetsutaro,Suzuki, Yutaka,Uesugi, Osamu,Oi, Shuichi,Miyano, Sotaro
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- Two-carbon homologation of aldehydes via silyl ketene acetals: A new stereoselective approach to (E)-alkenoic acids
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Aldehydes are converted into (E)-α,β-unsaturated carboxylic acids using C,O,O-tris(trimethylsilyl)ketene acetal 1. This organosilicon reagent is easily generated from trimethylsilyl acetate, LDA, and chlorotrimethylsilane. The effectiveness of the reaction has been explored for a large variety of aldehydes with Lewis acids and fluorides as catalysts.
- Bellassoued, Moncef,Lensen, Nathalie,Bakasse, Mina,Mouelhi, Sinda
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p. 8785 - 8789
(2007/10/03)
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- Carbonyl homologation via α-trimethylsilyl β-lactone rearrangements. A nonbasic alternative to the Wittig reaction
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Saturated and unsaturated aldehydes and ketones, when treated with trimethylsilylketene and BF3 for 16 hours, form β-lactones which spontaneously rearrange to α,β-unsaturated TMS esters; these hydrolyze during workup to form the corresponding carboxylic acids.
- Black,Zhang,Huang,Smith,Yates
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- Stereochemistry of Thermolytic Base-catalysed Decarboxylation to form Cojugated Diene-Acids: Synthesis using Ethylidenemalonic Ester Condensation
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The condensation of aromatic aldehydes with ethylidenemalonic ester in the presence of benzyltrimethylammonium hydroxide leads to 2(E),4(E)-half-esters, which are decarboxylated in refluxing pyridine to 2(E),4(E)-esters.When decarboxylated by thermolysis in quinoline at 130 deg C cinnamylidenemalonic acid gives almost pure 5-phenylpenta-2(Z),4(E)-dienoic acid which slowly stereomutates, but on continued heating at 170 deg C it passes over to give almost pure 2(E),4(E)-acid.In pyridine near its boiling point, however, the malonic acid is converted into a 64:36 mixture of 2(Z),4(E)-:2(E),4(E)-acids, the composition of which does not change on continued refluxing.The use of carboxy-labelled dideuteriomalonic acid in the pyridine reaction leads to 5-phenylpenta-2(Z),4(E)-dienoic acid and its 2(E),4(E)-stereoisomer, each having similar ca. 2.1 α/γ deuterium labelling.The latter stereoisomer does not arise by stereomutation, and a dual pathway originating from a common deuteriated lactone is proposed.Decarboxylation of the deuteriomalonic acid in quinoline at 130 deg C, giving almost pure 2(Z),4(E)-dienoic acid with ca. 2:1 α/γ labelling, involves only one of the pathways.The ethylidenemalonic acid method is suitable for the preparation of 2(E),4(E)-half-esters and 5-phenylpenta-2(Z),4(E)-dienoic acids having both electron-withdrawing as well as electron-releasing aryl substituents. 2(Z),4(E)-Sorbic acid can also be made from the corresponding malonic acid by quinoline-catalysed decarboxylation, whereas the classical pyridine-catalysed Doebner reaction forms almost entirely 2(E),4(E)-sorbic acid.
- Crombie, Leslie,Crombie, W. Mary L.
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p. 1267 - 1274
(2007/10/02)
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- Synthesis of 2(E),4(E)-Dienamides and 2(E),4(E)-Dienoates from 1,3-Dienes via 2-Phenylsulfonyl 1,3-Dienes
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A procedure for the preparation of 2E,4E unsaturated carboxylic acid derivatives from dienes was developed.Transformation of terminal 1,3-dienes to (E)-2-phenylsulfonyl 1,3-dienes and subsequent addition of a carboxy anion equivalent and elimination of benzenesulfinic acid led to 2,4-dienoic amides and esters.In this way the natural products N-isobutyl-2(E),4(E)-undecadienamide (1a), N-isobutyl-2(E),4(E)-decadienamide (pellitorine, 1b), and methyl 2(E),4(E)-decadienoate (1c) were obtained in high isomeric purity.
- Plobeck, Niklas A.,Baeckvall, Jan-E.
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p. 4508 - 4512
(2007/10/02)
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- Sorbic acid process
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Butadiene and acetic acid are reacted with metal ion oxidant to prepare acetoxyhexenoic acids which are then converted to sorbic acid.
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- Acyloxyalkenoic acids and process therefor
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This disclosure concerns acyloxyhexenoic acids and their salts with the acids being produced by reaction of butadiene and acetic acid with metal salt oxidants in a process involving electrolytic regeneration of the metal oxidants during the reaction. Iosmeric acetoxyhexenoic acids produced can be readily converted to sorbic acid, and antimicrobial and preservative uses for the acids are also disclosed.
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- DIENCARBONSAEUREN AUS 1,3-DIENEN UND CO2 DURCH C-C-VERKNUEPFUNG AN NICKEL(0)
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(Lig)Ni0 systems react with 1,3-dienes in the presence of CO2 to give nickela carboxylates.The influence of ligands and temperature on the regioselectivity of the C-C bond formation is elucidated.In some cases the nickela carboxylates undergo reductive elimination under the influence of maleic anhydride, and the coupled diene/CO2 moiety rearranges to give the diene carboxylic acid.A possible reaction sequence is discussed.
- Hoberg, H.,Schaefer, D.,Oster, B. W.
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p. 313 - 320
(2007/10/02)
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