- Development of mesoscopically assembled sulfated zirconia nanoparticles as promising heterogeneous and recyclable biodiesel catalysts
-
The nanoassembly of nearly monodisperse nanoparticles (NPs) as uniform building blocks to engineer zirconia (ZrO2) nanostructures with mesoscopic ordering by using a template as a fastening agent was explored. The mesophase of the materials was investigated through powder X-ray diffraction and TEM analysis (TEM) and N2 sorption studies. The TEM results revealed that the mesopores were created by the arrangement of ZrO2 NPs with sizes of 7.0-9.0nm and with broad interparticle pores. Moreover, the N2 sorption study confirmed the results. The surface chemical analysis was performed to estimate the distribution of Zr, O, and S in the sulfated ZrO2 matrices. The materials in this study displayed excellent catalytic activity in the biodiesel reaction for effective conversion of long-chain fatty acids to their methyl esters, and the maximum biodiesel yield was approximately 100%. The excellent heterogeneous catalytic activity could be attributed to the open framework, large surface area, presence of ample acidic sites located at the surface of the matrix, and high structural stability of the materials. The catalysts revealed a negligible loss of activity in the catalytic recycles.
- Das, Swapan K.,El-Safty, Sherif A.
-
-
Read Online
- Kinetic and molecular orbital analyses of dicarboxylic acylcarnitine methylesterification show that derivatization may affect the screening of newborns by tandem mass spectrometry
-
Newborns are routinely screened for organic acidemias by acylcarnitine analysis. We previously reported the partial catalytic methylesterification of dicarboxylic acylcarnitines by benzenesulfonic acid moiety in the solid extraction cartridge during extraction from serum. Since the diagnosis of organic acidemias by tandem mass spectrometry is affected by the higher molecular weight of these derivatized acylcarnitines, we investigated the methylesterification conditions. The kinetic constants for the methylesterification of carboxyl groups on the acyl and carnitine sides of carnitine were 2.5 and 0.24 h-1, respectively. The physical basis underlying this difference in methylesterification rates was clarified theoretically, illustrating that methylesterification during extraction proceeds easily and must be prevented.
- Maeda, Yasuhiro,Nakajima, Yoko,Gotoh, Kana,Hotta, Yuji,Kataoka, Tomoya,Sugiyama, Naruji,Shirai, Naohiro,Ito, Tetsuya,Kimura, Kazunori
-
-
Read Online
- Stoloniferins VIII-XII, resin glycosides, from Ipomoea stolonifera
-
Five new ether-soluble resin glycosides were isolated from whole plants of Ipomoea stolonifera. Their structures have been determined on the basis of chemical and spectral data. Similar to the resin glycosides previously isolated, all of them are monomers of a jalapinolic acid tetra- or penta- glycoside in which the sugar moiety is partially acylated by organic acids and also combined with the carboxy group of the aglycone to form a macrocyclic ester structure.
- Noda, Naoki,Takahashi, Naotsugu,Miyahara, Kazumoto,Yang, Chong-Ren
-
-
Read Online
- Defense Mechanisms of Arthropods. 83. α- and β-Necrodol, Novel Terpenes from a Carrion Beetle (Necrodes surinamensis, Silphidae, Coleoptera)
-
The defensive secretion obtained from the rectal gland of the carrion beetle Necrodes surinamensis has been found to consist of a mixture of aliphatic acids and terpene alcohols.Octanoic acid, decanoic acid, (Z)-3-decenoic acid, (Z)-4-decenoic acid, hexadecanoic acid, and octadecanoic acid are the chief acidic components.The three major terpenes are lavandulol and α- and β-necrodol.The necrodols were shown to have a 1,2,2,3,4-pentamethylcyclopentane framework not previously found among natural monoterpenes.Formulas 9 and 10 are derived for α- and β-necrodol, respectively, chiefly on the basis of mass spectrometric and NMR spectroscopic analysis.
- Roach, Braden,Eisner, Thomas,Meinwald, Jerrold
-
-
Read Online
- Lupeol-3-O-decanoate, a new triterpene ester from Cadaba farinosa Forssk. growing in Saudi Arabia
-
A new triterpene ester (1) together with eight known compounds (2-9) were isolated from the leaves of Cadaba farinosa Forssk. Their chemical structures were established on the basis of physical, chemical, and spectroscopic methods (IR, 1D and 2D NMR, and mass spectral analyses) to be: lupeol-3-O-decanoate (1), lupeol (2), β-sitosterol (3), ursolic acid (4), 12-aminododecanoic (5), dillenetin-3-O-β-d-glucopyranoside (6), stachydrine (7), 3-hydroxy-stachydrine (8), and quercetin-3-O-β-d-glucopyranoside (9). That is the first report for the isolation of compound 5 from a plant source. Compounds 5, 6, and 9 were evaluated for their antioxidant activity.
- Al-Musayeib, Nawal M.,Mohamed, Gamal A.,Ibrahim, Sabrin R. M.,Ross, Samir A.
-
-
Read Online
- AN 8-HYDROXYOCTADECA-CIS-11,14-DIENOIC ACID FROM MIRABILIS JALAPA SEED OIL
-
A fatty acid, found as a minor component in the seed oil of Mirabilis jalapa, is shown to be the hitherto unknown 8-hydroxyoctadeca-cis-11,14-dienoic acid. - Key Word Index: Mirabilis jalapa; Nyctaginaceae; seed oil; 8-hydroxyoctadeca-cis-11,14-dienoic acid.
- Ahmad, Mohammad Shamim,Rauf, Abdul,Mustafa, Jamal,Osman, Sheikh Mohammad
-
-
Read Online
- Bile acid hydrazides: Gelation, structural, physical and spectroscopic properties
-
Synthesis and gelation properties of a series of novel bile acid hydrazides are presented. These compounds are found to undergo self-assembly leading to organogelation in certain organic solvents. Compound 1 was found to be the most "effective" gelator in this series. The properties of this gel have been thoroughly investigated by conventional methods typical for molecular gel studies. Sol-gel transition temperature (Tg) of chloroform gels of compounds 1 and 3 was found to increase with increase in the chain length. Sol-gel transition was probed using the isothermal time test and results show that there is instantaneous increase in both the moduli after shear melting, which suggests that the kinetics of formation of the network was very fast. IR and NMR studies revealed hydrogen bonding between amidic carbonyl in the side chain and hydroxyl groups of cholic acid.
- Pore, Vandana S.,Agalave, Sandip G.,Pharande, Shrikant G.,Patil, Prashant A.,Kotmale, Amol S.
-
-
Read Online
- NEW BUTENOLIDES FROM THE GORGONIAN EUPLEXAURA FLAVA(NUTTING)
-
Four new butanolides (1a-d) were isolated from the Japanese gorgonian Euplexaura flava(Nutting).The structures of these compounds were elucidated from spectral data and chemical reactions.
- Kikuchi, Hiroyuki,Tsukitani, Yasumasa,Nakanishi, Hajime,Shimizu, Iwao
-
-
Read Online
- Lipophilic gold(I) complexes with 1,3,4-oxadiazol-2-thione or 1,3-thiazolidine-2-thione moieties: synthesis and their cytotoxic and antimicrobial activities
-
Novel lipophilic gold(I) complexes containing 1,3,4-oxadiazol-2-thione or 1,3-thiazolidine-2-thione derivatives were synthesized and characterized by IR, high resolution mass spectrometry, and 1H, 13C 31P NMR. The cytotoxicity of the compounds was evaluated considering cisplatin and/or auranofin as reference in different tumor cell lines: colon cancer (CT26WT), metastatic skin melanoma (B16F10), breast adenocarcinoma (MCF-7), cervical carcinoma (HeLa), glioblastoma (M059?J). Normal human lung fibroblasts (GM07492-A) and kidney normal cell (BHK-21) were also evaluated. The gold(I) complexes were more active than their respective free ligands and cisplatin. Furthermore, antibacterial activity was evaluated against Gram-positive bacteria Staphylococcus aureus ATCC 25213, Staphylococcus epidermidis ATCC 12228 and Gram-negative bacteria Escherichia coli ATCC 11229 and Pseudomonas aeruginosa ATCC 27853 and expressed as the minimum inhibitory concentration (MIC). The complexes exhibited lower MIC values when compared to the ligands and chloramphenicol against Gram-positive bacteria and Gram-negative bacteria. Escherichia coli was sensitive one to the action of gold(I) complexes.
- de Almeida, Angelina Maria,de Oliveira, Bruno Assis,de Castro, Pedro P?ssa,de Mendon?a, Camille Carvalho,Furtado, Ricardo Andrade,Nicolella, Heloiza Diniz,da Silva, Vania Lúcia,Diniz, Cláudio Galuppo,Tavares, Denise Crispim,Silva, Heveline,de Almeida, Mauro Vieira
-
-
Read Online
- Carbon-carbon bond fission on oxidation of primary alcohols to carboxylic acids
-
α-Carbon-carbon bond cleavage is shown to be a general side reaction accompanying the oxidation of unbranched primary alcohols to the corresponding carboxylic acids using HNO3, CrO3/H2SO 4/H2O/acetone, CrO3/CH3COOH, PDC/DMF, H5IO6/CrO3, KMnO4/H +, KMnO4/HO-, NiCl2/NaClO, TEMPO/PhI(OAc)2. Therefore, the product formed is always contaminated with a carboxylic acid containing one carbon atom less. Systems such as PhI(OAc)2/TEMPO or H5IO6/CrO 3/CH3CN reduce to a minimum the content of this impurity. Temperature, the order of reagent addition, and additives such as oxalic acid or cerium salts produce a profound effect on the formation of the undesirable impurity during the Jones oxidation of primary alcohols.
- Bekish, Andrei V.
-
-
Read Online
- Lipoxygenase inhibitory sphingolipids from Launaea nudicaulis
-
Four new sphingolipids: nudicaulin A [(2S,3S,4R,14E)-2-{[octadecanoyl] amino}tetraeicos-14-ene-1,3,4-triol; 1], nudicaulin B [(2S,3S,4R,14E)-2-{[(2R)- 2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 2], nudicaulin C [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3, 4-triol-1-O-β-d-glucopyranoside; 3], and nudicaulin D [(2S,3S,4R)-2-{[(2R, 3S,12E)-2,3-dihydroxyeicos-12-enoyl]amino}octadecane-1,3,4-triol; 4] together with 1-hexatriacontanol,-sitosterol, octadecyl 4-hydroxycinnamate, elaidic acid, cholesta-5,22-diene-3,7-diol, oleanolic acid, apigenin, and-sitosterol 3-O-β-d-glucopyranoside were isolated from the methanolic extract of the whole plant of Launaea nudicaulis. Their structures were elucidated using 1H and 13C NMR spectra and 2D NMR analyses (HMQC, HMBC, and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS, and HR-FAB-MS) experiments and comparison with literature data of related compounds. Compounds 1-4 displayed moderate inhibitory potential against enzyme lipoxygenase in concentration-dependent manner with IC50 value ranges 103-193M.
- Riaz, Naheed,Parveen, Shehla,Saleem, Muhammad,Ali, Muhammad Shaiq,Malik, Abdul,Ashraf, Muhammad,Afzal, Iftikhar,Jabbar, Abdul
-
-
Read Online
- Isolation and characterization of the chemical constituents from Plumeria rubra
-
Rubranonoside (=7-O-α-l-rhamnopyranosyl-4′-O-β-d- glucopyranosylnaringenin; (1), a new flavanone glycoside, rubranin (=(2S,3S,4R)-2-{[(2R,16E)-2-hydroxyhexaeico-16-en]amino}octadecane-1,3, 4-triol-1-O-β-d-glucopyranoside; (2), a new sphingolipid, rubradoid (plumieridine-1-O-β-d-galactopyranoside; (3), a new iridoid galactoside, rubrajaleelol (4) and rubrajaleelic acid (5), two new nor-terpenoids together with known iridoids: 1-α-plumieride (6), plumieride p-Z-coumarate (7) and plumieride-p-E-coumarate (8) have been isolated from the EtOAc-soluble fraction of the MeOH extract of Plumeria rubra. Their structures were assigned from 1H, 13C NMR spectra and 2D NMR analyses (COSY, NOESY, HMQC and HMBC experiments) in combination with HRMS experiments and comparison with literature data of related compounds. All the isolates (1-8) were tested for their antioxidant, antiurease, cytotoxic and phytotoxic activities and were found almost inactive.
- Akhtar, Nasim,Saleem, Muhammad,Riaz, Naheed,Ali, M. Shaiq,Yaqoob, Asma,Nasim, Faiz-Ul-Hassan,Jabbar, Abdul
-
-
Read Online
- Transesterification catalyzed by lanthanum complex grafted upon hydrotalcite as a macroligand
-
Lanthanum species grafted upon hydrotalcite(HT) catalyzed transesterification of various esters in methanol solution. In this system, HT acted as a macroligand for lanthanum species through the complexation of the surface hydroxyl group of HT. HT-like compound containing La(III) in its brucite layer and simple La(III) salts showed low and/or no catalytic activity for the transesterification. The combined system of lanthanum ion and HT (La/HT) was important for demonstrating the catalytic activity. Moreover, the activity of the La/HT catalyst increased by treatment with aqueous alkaline but decreased by the reaction in anhydrous methanol. Since the hydrophilicity around the surface of La/HT was essential in the reaction for the catalytic activity, the substrate containing hydrophilic function was easily transformed. The structure of the active La/HT catalyst generated upon the HT surface might be a dinuclear lanthanum complex having aqua and hydroxo ligands, which acted as general acid and base, respectively. This catalyst was able to reuse by handling with slightly alkaline water.
- Yagyu, Takeyoshi,Mizuno, Yuki,Jitsukawa, Koichiro
-
-
Read Online
- Convenient method for the synthesis of N-(ethyloxycarbonyl) ester derivatives from amino acids
-
Amino acids upon treatment with ethyl chloroformate in methanol in the presence of potassium carbonate give the corresponding N-(ethyloxycarbonyl) amino acid ester derivatives in good yields. These derivatives can be also synthesized by performing the reaction in THF in the presence of alcohols.
- Kanth,Periasamy
-
-
Read Online
- STRUCTURES AND SYNTHESIS OF SEED-GERMINATION INHIBITORS FROM HIBISCUS ROSA-SINENSIS
-
Key Word Index - Hibiscus rosa-sinensis; Malvaceae; seed germination; inhibition; acetylenic acids; o-nitrophenyl selenide. 8-Nonynoic, 9-decynoic acids and their methyl esters were isolated for the first time as natural products from Hibiscus rosa-sinensis.They were inhibitors of the germination of lettuce seeds and were synthesized via o-nitrophenyl selenides.
- Nakatani, Munehiro,Yamachika, Takashi,Tanoue, Takao,Hase, Tsunao
-
-
Read Online
- DITERPENES FROM THE LATEX OF EUPHORBIA BROTERI
-
Six polycyclic diterpenes have been isolated from the latex of Euphorbia broteri Daveau.Two had a tigliane skeleton: 12-O-(2Z,4E-octadienoyl)-4-deoxyphorbol-13,20-diacetate and 12-O-(2Z,4E-octadienoyl)-phorbol-13,20-diacetate and four an ingenane skeleton: 20-acetyl-ingenol-3-decadienoate, 3-O-tetradecanoyl-ingenol, 20-O-tetradecanoyl-ingenol and 5-O-tetradecanoyl-ingenol.The second and last two compounds are described as natural compounds for the first time.Their structures were established by spectroscopic methods, by chemical correlations and by H/H and C/H correlations in their 1H NMR and 13C NMR spectra.Key Word Index - Euphorbia broteri; Euphorbiaceae; latex; proinflammatory fractions; ingenol and phorbol mono-,di- and triesters; tetracyclic diterpenes.
- a Jose Sexmero,Marcos, Isidro Sanchez
-
-
Read Online
- Hydrazidomycins, cytotoxic alkylhydrazides from Streptomyces atratus
-
Three unusual alkyhydrazide natural products, named hydrazidomycin A (1), B (2) and C (3), were isolated from the chloroform extract of a Streptomyces atratus culture, and their structures were elucidated by MS and NMR techniques. Hydrazidomycins A-C exhibited moderate to strong cytotoxic activities in a panel of 42 cell lines, with hydrazidomycin A being the most potent compound (mean IC50 = 0.37 μM).
- Ueberschaar, Nico,Ndejouong, Basile Le Sage Tchize,Ding, Ling,Maier, Armin,Fiebig, Heinz-Herbert,Hertweck, Christian
-
-
Read Online
- Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments
-
Most of the well-known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+, and NADPH as co-substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.
- Pongpamorn, Pornkanok,Kiattisewee, Cholpisit,Kittipanukul, Narongyot,Jaroensuk, Juthamas,Trisrivirat, Duangthip,Maenpuen, Somchart,Chaiyen, Pimchai
-
supporting information
p. 5749 - 5753
(2021/02/01)
-
- Ruthenium-catalyzed hydrogenation of CO2as a route to methyl esters for use as biofuels or fine chemicals
-
A novel robust diphosphine-ruthenium(ii) complex has been developed that can efficiently catalyze both the hydrogenation of CO2 to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO2 to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO2 as a C1 source for the production of biofuels, fine chemicals and methanol.
- Li, Yong,Liu, Qingbin,Ma, Yanping,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Zhang, Qiuyue,Zhao, Ziwei,Zhong, Yanxia
-
p. 6766 - 6774
(2020/08/25)
-
- Method of Preparing Aminoundecane Acid and 11-Aminoundecanoic Acid or Structural Isomer Thereof by Hydroformylation Reaction
-
The present invention relates to a method for preparing 11-aminoundecanoic acid or structural isomers thereof using a hydroformylation reaction. More particularly, the present invention is an eco-friendly method capable of preparing aminoundecanoic acid used as a monomer of polyamide and structural isomers thereof from an olefinic acid ester obtained through a metathesis reaction of oleic acid by means of hydroformylation, reductive amination reaction, and hydrolysis reaction, and capable of producing various polyamides having different physical properties according to a ratio of each isomer since the ratio of structural isomers can be adjusted according to a ligand.COPYRIGHT KIPO 2021
- -
-
Paragraph 0068; 0074-0095; 0119-0122
(2020/11/03)
-
- Structure determination of fatty acid ester biofuels via in situ cryocrystallisation and single crystal X-ray diffraction
-
In situ cryocrystallisation in combination with a zone-melting technique enabled the crystal structure determination of a homologous series of low-melting n-alkyl methyl esters Cn-1H2n+1CO2CH3, from methyl pentanoate (n = 5) to methyl tridecanoate (n = 13), by single crystal X-ray diffraction. Two isostructural groups were identified: the odd-numbered triclinic members (C9,11,13) and the even-numbered orthorhombic members (C8,10,12). All observed structural trends, similarities and differences in intermolecular contacts, including the odd-even effect observable in melting point behaviour and unit cell parameters, were easily visualised and described by 2D fingerprint plots generated from the calculated Hirshfeld surfaces, in combination with atom-atom Coulomb-London-Pauli (AA-CLP) lattice energy calculations.
- Prathapa, Siriyara Jagannatha,Slabbert, Cara,Fernandes, Manuel A.,Lemmerer, Andreas
-
-
- Preparation method of long-chain ester
-
The invention relates to the field of organic synthesis and provides a preparation method of long-chain ester, which comprises the following steps: carrying out esterification reaction of the carboxylic acid and the alcohol through a catalyst and obtaining a long-chain ester phase and a water phase post the standing and layering of the reaction liquid; the catalyst comprises ionic liquid or eutectic solvent; purifying and separating the long-chain ester phase to obtain high-purity long-chain ester; introducing the residual substance again into the esterification reaction system for reaction after the water in the water phase is removed. The yield and the purity of the long-chain ester prepared by the invented method are as high as 99.8% and 99% respectively as indicated by the embodiment of the preparation method.
- -
-
Paragraph 0115; 0116; 0117
(2019/03/23)
-
- Medium-chain fatty acids from Eugenia winzerlingii leaves causing insect settling deterrent, nematicidal, and phytotoxic effects
-
Eugenia winzerlingii (Myrtaceae) is an endemic plant from the Yucatan peninsula. Its organic extracts and fractions from leaves have been tested on two phloem-feeding insects, Bemisia tabaci and Myzus persicae, on two plant parasitic nematodes, Meloidogyne incognita and Meloidogyne javanica, and phytotoxicity on Lolium perenne and Solanum lycopersicum. Results showed that both the hexane extract and the ethyl acetate extract, as well as the fractions, have strong antifeedant and nematicidal effects. Gas chromatography-mass spectrometry analyses of methylated active fractions revealed the presence of a mixture of fatty acids. Authentic standards of detected fatty acids and methyl and ethyl derivatives were tested on target organisms. The most active compounds were decanoic, undecanoic, and dodecanoic acids. Methyl and ethyl ester derivatives had lower effects in comparison with free fatty acids. Dose-response experiments showed that undecanoic acid was the most potent compound with EC50 values of 21 and 6 nmol/cm2 for M. persicae and B. tabaci, respectively, and 192 and 64 nmol for M. incognita and M. javanica, respectively. In a phytotoxicity assay, medium-chain fatty acids caused a decrease of 38-52% in root length and 50-60% in leaf length of L. perenne, but no effects were observed on S. lycopersicum. This study highlights the importance of the genus Eugenia as a source of bioactive metabolites for plant pest management.
- Cruz-Estrada, Angel,Ruiz-Sánchez, Esaú,Cristóbal-Alejo, Jairo,González-Coloma, Azucena,Andrés, María Fe,Gamboa-Angulo, Marcela
-
-
- Structural and theoretical studies of the methoxycarbonylation of higher olefins catalysed by (Pyrazolyl-ethyl)pyridine palladium (II) complexes
-
Reactions of 2-[1-(3,5-dimethylpyrazol-1-yl)ethyl]pyridine (L1) and 2-[1-(3,5-diphenylpyrazol-1-yl)ethyl]pyridine (L2) with the [Pd (COD)Cl2] or [Pd (COD)MeCl] produced palladium (II) complexes [Pd(L1)ClMe] (1), [Pd(L1)Cl2] (C2), [Pd(L2)ClMe] (3), and [Pd(L2)Cl2] (4) in quantitative yields. Solid state structures of complexes 1, 3 and 4 established the formation of mononuclear compounds, containing one bidentate ligand unit per metal atom, to give square planar complexes. All the other spectroscopic characterization data and elemental analyses were consistent with the observed structures. All the palladium (II) complexes 1–4 gave active catalysts in the methoxycarbonylation of 1-octenes. The catalysts demonstrated 100% chemoselectivities towards esters and favored the formation of linear isomers. Reaction conditions such as the type of phosphine derivative, acid promoter, solvent system, time, pressure and temperature have been investigated and shown to affect both the catalytic activity and regio-selectivity of the catalysts. Solid-angle modelling established the comparable steric contributions from the ligands, consistent with the similar regioselectivities of the resultant catalysts.
- Zulu, Siyabonga,Alam, Mohd.G.,Alam, Mohd. G.,Ojwach, Stephen O.,Akerman, Matthew P.
-
-
- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
-
Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
-
supporting information
p. 3931 - 3943
(2018/09/11)
-
- Synthesis of medium-chain carboxylic acids or α,ω-dicarboxylic acids from cellulose-derived platform chemicals
-
Medium-chain fatty acids and their derivatives have important applications in the energy and chemical industries. Thus, we have prepared a series of medium-chain fatty acids by the selective hydrodeoxygenation of the aldol condensation products derived from cellulose using a metal triflate and Pd/C catalyst system. The selective retention of the carboxyl group is a notable feature of this catalytic system.
- Li, Xing-Long,Zhang, Kun,Jiang, Ju-Long,Zhu, Rui,Wu, Wei-Peng,Deng, Jin,Fu, Yao
-
supporting information
p. 362 - 368
(2018/02/07)
-
- One-pot oxidative bromination – Esterification of aldehydes to 2-bromoesters using cerium (IV) ammonium nitrate and lithium bromide
-
A two-step, one-pot reaction of aldehydes with the CAN/LiBr oxidation system under solvent-free conditions followed by the addition of methanol affords methyl α-bromocarboxylates. The oxidation of aldehydes with methanol using this system gives only methyl esters. A facile method, which does not require special equipment, was developed for the synthesis of 2-bromoesters from aliphatic aldehydes with carbon chain lengths of 5–10 atoms.
- Nikishin, Gennady I.,Kapustina, Nadezhda I.,Sokova, Lyubov L.,Bityukov, Oleg V.,Terent'ev, Alexander O.
-
supporting information
p. 352 - 354
(2017/01/03)
-
- Chromatographic and chromato-mass spectral characterization of amino acids derivatives formed via the interaction with dimethyl acetal of dimethylformamide
-
A series of amino acids have been converted into the derivatives via interaction with dimethylformamide dimethyl acetal for gas chromatography identification. The derivatives have been for the first time characterized with mass spectra and retention indices corresponding to the standard nonpolar polydimethylsiloxane stationary phases. Basic features of mass spectroscopic fragmentation of the derivatives have been stated; the rules for interpretation of their gas chromatography retention indices have been figured out, including the additive scheme elements.
- Zenkevich,Pushkareva
-
p. 1920 - 1928
(2015/10/12)
-
- Palladium complexes of (benzoimidazol-2-ylmethyl)amine ligands as catalysts for methoxycarbonylation of olefins
-
Reactions of N-(1H-benzoimidazol-2-ylmethyl)-2-methoxy aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl)-2-bromo aniline (L2) with either [PdCl2(COD)] or [PdClMe(COD)] afforded the neutral palladium complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2) and [PdClMe(L2] (3), respectively. Treatment of 2 and 3 with one equivalent of PPh3 in the presence of NaBAr4 (Ar = 3,5-(CF3)2C6H3) produced the corresponding cationic species, [PdMe(L1)]BAr4 (4) and [PdMe(L2)]BAr4 (5). All the palladium complexes formed active catalysts in the methoxycarbonylation of alkenes to produce linear and branched esters. The catalytic behaviour was dependent on the catalyst structure, presence of PPh3, acid promoter and alkene chain length.
- Tshabalala, Thandeka A.,Ojwach, Stephen O.,Akerman, Matthew A.
-
p. 178 - 184
(2015/06/25)
-
- A novel aromatic carbocation-based coupling reagent for esterification and amidation reactions
-
A novel tropylium-based coupling reagent has been developed to facilitate the synthesis of a series of esters, amides, lactones and peptides under mild reaction conditions. Remarkably, this reagent can be used in catalytic amounts in conjunction with a sacrificial reagent, offering a new and efficient method for nucleophilic coupling reactions of carboxylic acids.
- Nguyen, Thanh V.,Lyons, Demelza J.M.
-
supporting information
p. 3131 - 3134
(2015/06/17)
-
- Agent having neurotrophic factor-like activity
-
The present invention provides a pharmaceutical agent having high safety and a neurotrophic factor-like activity, which contains, as an active ingredient, any one compound included in fatty acids each having 8 carbon atoms (C8) or having 10 carbon atoms (C10) to 12 carbon atoms (C12) or fatty acid esters thereof, such as 3,7-dimethyloctanoic acid ethyl ester, geranicacidethyl ester, and the like, eachof whichhas 8 carbonatoms (C8), decanoic acid methyl ester, trans-2-decenoic acid, trans-2-decenoic acid methyl ester, trans-2-decenoic acid ethyl ester, trans-2-decenoic acid-2-decenyl ester, trans-2-decenoic acid cyclohexyl ester, trans-2-decenoic acid isopropyl ester, trans-3-decenoic acid methyl ester, trans-9-decenoic acid methyl ester, and the like, each of which has 10 carbon atoms (C10), trans-10-undecenoic acid methyl ester, trans-10-undecenoic acid ethyl ester, and the like, each of which has 11 carbon atoms (C11), and dodecanoic acid, and the like, each of which has 12 carbon atoms (C12), or salts thereof or prodrugs thereof.
- -
-
Paragraph 0025-0026
(2016/01/25)
-
- A General and mild catalytic α-alkylation of unactivated esters using Alcohols
-
Catalytic α-alkylation of esters with primary alcohols is a desirable process because it uses low-toxicity agents and generates water as the by-product. Reported herein is a NCP pincer/Ir catalyst which is highly efficient for α-alkylation of a broad scope of unactivated esters under mild reaction conditions. For the first time, alcohols alkylate unactivated α-substituted acyclic esters, lactones, and even methyl and ethyl acetates. This method can be applied to the synthesis of carboxylic acid derivatives with diverse structures and functional groups, some of which would be impossible to access by conventional enolate alkylations with alkyl halides. In a pinch: An NCP pincer/iridium catalyst is highly efficient for the α-alkylation of unactivated esters using alcohol under mild reaction conditions. The reaction is simple, clean, and scalable (1-10 mmol), and the scope with respect to the ester is wide.
- Guo, Le,Ma, Xiaochen,Fang, Huaquan,Jia, Xiangqing,Huang, Zheng
-
supporting information
p. 4023 - 4027
(2015/03/30)
-
- Biochemical Studies of Mycobacterial Fatty Acid Methyltransferase: A Catalyst for the Enzymatic Production of Biodiesel
-
Summary Transesterification of fatty acids yields the essential component of biodiesel, but current processes are cost-prohibitive and generate waste. Recent efforts make use of biocatalysts that are effective in diverting products from primary metabolism to yield fatty acid methyl esters in bacteria. These biotransformations require the fatty acid O-methyltransferase (FAMT) from Mycobacterium marinum (MmFAMT). Although this activity was first reported in the literature in 1970, the FAMTs have yet to be biochemically characterized. Here, we describe several crystal structures of MmFAMT, which highlight an unexpected structural conservation with methyltransferases that are involved in plant natural product metabolism. The determinants for ligand recognition are analyzed by kinetic analysis of structure-based active-site variants. These studies reveal how an architectural fold employed in plant natural product biosynthesis is used in bacterial fatty acid O-methylation. Mycobacterial fatty acid methyltransferases are employed as biocatalysts for the production of biodiesel. Petronikolou and Nair describe structural and biochemical characterization of a mycobacterial fatty acid methyltransferase, reveal an unexpected homology to enzymes involved in plant primary metabolism, and provide insights into substrate preference.
- Petronikolou, Nektaria,Nair, Satish K.
-
p. 1480 - 1490
(2015/12/01)
-
- Four new pentasaccharide resin glycosides from Ipomoea cairica with strong α-glucosidase inhibitory activity
-
Six pentasaccharide resin glycosides from Ipomoea cairica, including four new acylated pentasaccharide resin glycosides, namely cairicoside I-IV (1-4) and the two known compounds cairicoside A (5) and cairicoside C (6), were isolated from the aerial parts of Ipomoea cairica. Their structures were established by a combination of spectroscopic, including two dimensional (2D) NMR and chemical methods. The core of the six compounds was simonic acid A, and they were esterfied the same sites, just differing in the substituent groups. The lactonization site of the aglycone was bonded to the second saccharide moiety at C-2 in 1-4, and at C-3 in 5-6. Compounds 1 and 5, 4 and 6 were two pairs of isomers. The absolute configuration of the aglycone in 1-6 which was (11S)-hydroxyhexadecanoic acid (jalapinolic acid) was established by Mosher's method. Compounds 1-4 have been evaluated for inhibitory activity against α-glucosidase, which all showed inhibitory activities.
- Pan, Jie-Tao,Yu, Bang-Wei,Yin, Yong-Qin,Li, Jie-Hong,Wang, Li,Guo, Li-Bing,Shen, Zhi-Bin
-
p. 6601 - 6610
(2015/05/13)
-
- One-pot esterification and amide formation via acid-catalyzed dehydration and ritter reactions
-
Esterification of carboxylic acid is achieved using acetonitrile as a water trap. Water liberated during esterification is consumed in cyanide hydrolysis, thereby driving the esterification to completion. Substrates having carboxylic acid and nitrile groups undergo intramolecular dehydration and rehydration to amido esters in the absence of acetonitrile. Cyano acids also undergo esterification and Ritter reaction in one pot when excess alcohol is used. For the first time, we have observed an interesting Ritter reaction of primary alcohols, leading to ester amide product in one pot. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Dawar, Pankaj,Raju, M. Bagavan,Ramakrishna, Ramesha Andagar
-
supporting information
p. 836 - 846
(2014/03/21)
-
- Efficient microwave-assisted esterification reaction employing methanesulfonic acid supported on alumina as catalyst
-
A rapid and efficient protocol assisted by microwave irradiation for the synthesis of esters using methanesulfonic acid (CH3SO3H) supported on Al2O3 (AMA) as catalyst and free of solvent is described. The products were obtained in good yields and purity, with reduced reaction time, and the process is simple and environmentally benign. Copyright
- Fabian, Lucas,Gomez, Matias,Kuran, Juan A. Caturelli,Moltrasio, Graciela,Moglioni, Albertina
-
p. 2386 - 2392
(2014/07/22)
-
- Metal/bromide autoxidation of triglycerides for the preparation of FAMES to improve the cold-flow characteristics of biodiesel
-
Triglyceride autoxidation using a homogeneous Co/Mn/Zr/bromide catalyst in acetic acid (93%) of low grade tallow, canola oil or soy bean oil in a batch reactor at 150 °C for 2 h, produced lower molecular weight products relative to the fatty acids of the starting triglycerides. For the autoxidation of tallow the main products after esterification were monoesters Me(CH 2)mC(O)OMe (m = 5-12) and diesters MeOC(O)(CH 2)nC(O)OMe, (n = 7-12). Oxidation of the saturated fatty acids in triglycerides was confirmed and modelled using methyl palmitate. Post-treatment esterification of tallow autoxidation products to produce biodiesel (BD) esters resulted in improved cold temperature properties by a mean of 13.0 °C, i.e. a mean cloud point (CP) 1.0 °C (cf. unmodified tallow biodiesel: CP 14 °C).
- Phung, Peter,Rowlands, William N.,Thiyakesan, Appadurai,Benndorf, Paul,Masters, Anthony F.,Maschmeyer, Thomas
-
p. 162 - 168
(2014/07/07)
-
- Direct dehydrative esterification of alcohols and carboxylic acids with a macroporous polymeric acid catalyst
-
A macroporous polymeric acid catalyst was prepared for the direct esterification of carboxylic acids and alcohols that proceeded at 50-80 C without removal of water to give the corresponding esters with high yield. Flow esterification for the synthesis of biodiesel fuel was also achieved by using a column-packed macroporous acid catalyst under mild conditions without removal of water.
- Minakawa, Maki,Baek, Heeyoel,Yamada, Yoichi M. A.,Han, Jin Wook,Uozumi, Yasuhiro
-
supporting information
p. 5798 - 5801
(2013/12/04)
-
- Tailoring metal-organic framework catalysts by click chemistry
-
We successively introduce new catalytic centers through click reaction into MOFs and modify their environment by addition of lipophilic groups. The resulting bifunctionalized MOF provides an optimized balance between basicity and lipophilicity and shows outstanding performance for the transesterification reaction. The Royal Society of Chemistry 2012.
- Savonnet, Marie,Camarata, Aurelie,Canivet, Jerome,Bazer-Bachi, Delphine,Bats, Nicolas,Lecocq, Vincent,Pinel, Catherine,Farrusseng, David
-
supporting information; experimental part
p. 3945 - 3948
(2012/05/07)
-
- Ultrasound-assisted synthesis of aliphatic acid esters at room temperature
-
This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions.
- Hobuss, Cristiane B.,Venzke, Dalila,Pacheco, Bruna S.,Souza, Alexander O.,Santos, Marco A.Z.,Moura, Sidnei,Quina, Frank H.,Fiametti, Karina G.,Vladimir Oliveira,Pereira, Claudio M.P.
-
experimental part
p. 387 - 389
(2012/04/23)
-
- Specific enzyme-catalyzed hydrolysis and synthesis in aqueous and organic medium using biocatalysts with lipase activity from Aspergillus niger MYA 135
-
In the present study, the specific hydrolytic activity of three biocatalysts such as the constitutive mycelium-bound lipase, the induced mycelium-bound lipase and the lyophilized induced supernatant from A. niger MYA 135 was evaluated in both aqueous and organic media.A direct correlation between activity in water and n-hexane was not observed for the same hydrolytic reaction. The n-hexane/water activity ratio (RO/A) was applied to characterize the activity in organic medium. The three biocatalysts showed RO/A values higher than 1 for hydrolysis of long-chain fatty acid esters, demonstrating a higher specific hydrolytic activity in organic solvent than in water. A different behavior was observed during hydrolysis of middle-chain fatty acid esters, which was higher in aqueous medium (R O/Adw) observed in a reaction mixture containing propanol and p-nitrophenyl laurate. Finally, both p-nitrophenyl caprate (C10) and p-nitrophenyl laurate (C12) were preferentially methanolized by the lyophilized induced supernatant, being this lipase activity the most specific biocatalyst preparation under transesterification conditions. A selectivity-based analysis of each lipase preparation toward transesterification or hydrolysis in organic medium was evaluated as well. Springer Science+Business Media, LLC 2012.
- Romero, Cintia M.,Pera, Licia M.,Loto, Flavia,Baigori, Mario D.
-
p. 1361 - 1368
(2013/01/15)
-
- Methyl ricinoleate as platform chemical for simultaneous production of fine chemicals and polymer precursors
-
The modification of methyl ricinoleate by etherification of the hydroxyl group was accomplished by using a nonclassical ruthenium-catalyzed allylation reaction and also by esterification. Methyl ricinoleate derivatives were engaged in ring-closing metathesis (RCM) reactions leading to biosourced 3,6-dihydropyran and α,β-unsaturated lactone derivatives with concomitant production of polymer precursors. Sequential RCM/hydrogenation and RCM/cross-metathesis were also implemented as a straightforward method for the synthesis of tetrahydropyran and lactone derivatives as well as valuable monomers (i.e., polyamide precursors).
- Dupe, Antoine,Achard, Mathieu,Fischmeister, Cedric,Bruneau, Christian
-
p. 2249 - 2254
(2013/01/15)
-
- HYDRAZIDOMYCINS
-
The present invention relates to pharmaceutical formulations comprising specific hydrazidomycin compounds. Since said hydrazidomycin compounds show cytotoxic activities, the present invention further relates to said hydrazidomycin compounds for use in medicine, in particular in the treatment of proliferative disorders.
- -
-
Page/Page column 7-8
(2012/12/13)
-
- Hydrazidomycins
-
The present invention relates to pharmaceutical formulations comprising specific hydrazidomycin compounds. Since said hydrazidomycin compounds show cytotoxic activities, the present invention further relates to said hydrazidomycin compounds for use in medicine, in particular in the treatment of proliferative disorders.
- -
-
Page/Page column 4-5
(2012/12/13)
-
- Iridium-catalyzed oxidative methyl esterification of primary alcohols and diols with methanol
-
Oxidative methyl esterification of primary alcohols and diols with methanol was successfully achieved, using acetone as a hydrogen acceptor, under the influence of an iridium complex combined with 2-(methylamino)ethanol (MAE) as catalyst.
- Yamamoto, Nobuyuki,Obora, Yasushi,Ishii, Yasutaka
-
experimental part
p. 2937 - 2941
(2011/05/30)
-
- Synthesis, antimicrobial evaluation, QSAR and in silico ADMET studies of decanoic acid derivatives
-
Various derivatives of decanoic acid (CD) have been synthesized and evaluated against Gram positive B. subtilis, S. aureus and Gram negative E. coli bacteria as well as against fungi C. albicans and A. niger. Quantitative structure activity relationship (QSAR) models for antimicrobial activities were developed using multiple linear regression and cross validated by leave one out (LOO) approach. QSAR studies indicated that activity against Gram positive bacteria was governed by lipophilicity of the compounds while topological steric nature of the molecule was deciding factor for antifungal activity. Further, in silico ADMET studies showed that compounds CD12, 19, 20 and 23 could be explored further for other activities.
- Kumar, Ashwani,Singh, Surender,Jain, Sandeep,Kumar, Parvin
-
experimental part
p. 191 - 204
(2011/10/09)
-
- Synthesis of some novel 2,5-disubstituted thiazolidinones from a long chain fatty acid as possible anti-inflammatory, analgesic and hydrogen peroxide scavenging agents
-
Some new decanoic acid [2,5-disubstituted-4-oxo-thiazolidin-3-yl]amides (6a-j) have been synthesised by the condensation of decanoic acid hydrazide with various aromatic aldehydes to yield the Schiff's bases. Cyclocondensation of the Schiff's bases with thioglycollic acid afforded 4-thiazolidinone derivatives. The structures of the newly synthesised compounds were confirmed by analytical and spectral methods. The anti-inflammatory, analgesic and antioxidant activity of the title compounds were evaluated. Compound 6j exhibited 44.84 % inhibition of inflammation and was the most potent anti-inflammatory agent of the series whereas compound 6f demonstrated the most potent analgesic activity (69.82% inhibition of writhing) followed by compounds 6e and 6g. All the synthesised compounds exhibited a potent antioxidant activity.
- Kumar, Vipin,Sharma, Archana,Chander Sharma, Prabodh
-
experimental part
p. 198 - 203
(2011/10/18)
-
- Thiazolidin-4-one and hydrazone derivatives of capric acid as possible anti-inflammatory, analgesic and hydrogen peroxide-scavenging agents
-
Starting from capric acid, hydrazone and thiazolidin-4-one derivatives have been synthesized in the present investigation. Decanoic acid hydrazide was reacted appropriately to yield hydrazones, which were then cyclized to yield the corresponding thiazolidin-4-ones. The structures of the newly synthesized compounds were confirmed by analytical and spectral methods. Anti-inflammatory, analgesic, and hydrogen peroxide-scavenging activity of the title compounds were evaluated. Among synthesized compounds, 2-hydroxyphenyl thiazolidinone with 44.90% inhibition of inflammation was the most potent anti-inflammatory agent. Similarly, 4-methoxybenzylidine hydrazide with 64.90% inhibition of writhing was observed to be the most potent analgesic agent of the synthesized compounds. All the synthesized compounds exhibited potent hydrogen peroxide-scavenging activity.
- Sharma, Archana,Kumar, Vipin,Jain, Sandeep,Sharma, Prabodh Chander
-
experimental part
p. 546 - 552
(2012/06/01)
-
- Isolation of the β-galactosphingolipid coniferoside using a tumor cell proteome reverse affinity protocol
-
New approaches are vital to the development of marine natural products (MNP) as therapeutic leads. One of the more time consuming aspects of MNP research arises in the connection between structure and function. Here, we describe an isolation protocol that adapts tumor cell proteomes as a vehicle for MNP isolation therein uniting structural and functional analysis. Application of this method to extracts of the sponge Agelas conifera led to the isolation of a unique poly-hydroxybutyrated β-galactosphingolipid, coniferoside.
- La Clair, James J.,Rodriguez, Abimael D.
-
experimental part
p. 6645 - 6653
(2011/12/21)
-
- One-pot esterification and Ritter reaction: Chemo- and regioselectivity from tert-butyl methyl ether
-
tert-Butyl methyl ether (TBME) has been effectively used as a reagent for esterification of carboxylic acids. By varying amounts of sulfuric acid, a remarkable regioselectivity in esterification has been demonstrated. Additionally, under the present reaction conditions, one-pot esterification and Ritter reaction are achieved in almost quantitative yield.
- Dawar, Pankaj,Bhagavan Raju,Ramakrishna, Ramesha A.
-
supporting information; experimental part
p. 4262 - 4265
(2011/08/21)
-
- New eutectic ionic liquids for lipase activation and enzymatic preparation of biodiesel
-
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
-
supporting information; experimental part
p. 1908 - 1916
(2011/04/23)
-
- Solvent free base catalysis and transesterification over basic functionalised Metal-Organic Frameworks
-
Metal-Organic Frameworks (post-)functionalised with nitrogen containing moieties undergo solvent free aza-Michael condensation and transesterification, surpassing molecular and functionalised MCM-type analogues. The Royal Society of Chemistry 2009.
- Savonnet, Marie,Aguado, Sonia,Ravon, Ugo,Bazer-Bachi, Delphine,Lecocq, Vincent,Bats, Nicolas,Pinel, Catherine,Farrusseng, David
-
experimental part
p. 1729 - 1732
(2011/03/20)
-
- Three new pentasaccharide resin glycosides from the roots of sweet potato (Ipomoea batatas)
-
Three new pentasaccharide resin glycosides, batatosides III-V (1-3), were isolated from the roots of Sweet potato (Ipomoea batatas). Saponification of the crude resin glycoside mixture yielded substituents and simonic acid B. The structures of the isolate
- Yin, Yong-Qin,Huang, Xue-Feng,Kong, Ling-Yi,Niwa, Masatake
-
experimental part
p. 1670 - 1674
(2009/12/04)
-
- Molecular iodine as efficient co-catalyst for facile oxidation of alcohols with hypervalent(III) iodine
-
A simple and mild procedure for the facile oxidation of alcohols to ketones and acids using a catalytic quantity of molecular iodine in combination with (diacetoxyiodo)benzene in acetonitrile is described. Direct oxidative methyl esterification of alcohols is also reported in methanol as solvent. Oxidation of alcohols is induced by iodonium ion generated in situ by the chemical oxidation of molecular iodine with (diacetoxyiodo)benzene. Georg Thieme Verlag Stuttgart.
- Karade,Tiwari,Huple
-
p. 2039 - 2042
(2007/10/03)
-
- Solvent-modulated chemoselective deprotections of trialkylsilyl esters and chemoselective esterifications
-
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
-
p. 6305 - 6309
(2007/10/03)
-
