- Synthesis of (±)tetrahydromyricoidine
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A total synthesis of the spermidine alkaloid (±)-tetrahydromyricoidine (6) was achieved by using two ring enlargement reactions. The difficulties experienced in the second ring enlargement step, a transamidation reaction with a medium ring sized lactam bearing two bulky groups are discussed. These were overcome by altering the reaction sequence and the transamidation reaction was successfully carried out by at first deprotection of the Boc function. spermidine alkaloids; (±)-tetrahydromyricoidine; ring enlargement.
- Song, Jiangao,Hesse, Manfred
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Read Online
- Compound with cinnamon fragrance as well as preparation method and application thereof
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The invention relates to a compound with cinnamon fragrance as well as a preparation method and application thereof. The compound has the following structural formula, wherein the structural formula can be named as 2-decenoic acid-2-(4-methoxy)-phenyl-2-butyl ester. The provided compound has the advantages of obvious cinnamon aroma, rich aroma, lasting aroma and good stability, and enriches the sources of cinnamon aroma. When the essence is prepared in different periods, the compound has consistent cinnamon aroma, so that the required aroma can be accurately mastered.
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Paragraph 0104; 0112-0114; 0126; 0132-0133; 0137-0138; 0141
(2021/04/10)
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- ANTI-BACTERIAL CALCIUM-DEPENDENT ANTIBIOTIC (CDA) ANALOGS AND METHODS OF TREATING BACTERIAL INFECTIONS
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Provided herein are calcium-dependent antibiotics (CDAs), as a novel therapeutic target for treating bacterial infections. The present invention also relates to pharmaceutical compositions comprising such compounds, and to methods of use thereof for combating bacteria and treating bacterial infections.
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Paragraph 0134; 0136
(2021/10/22)
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- Profiling structural diversity and activity of 2-alkyl-4(1H)-quinoloneN-oxides ofPseudomonasandBurkholderia
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We synthesized all major saturated and unsaturated 2-alkyl-4(1H)-quinoloneN-oxides ofPseudomonasandBurkholderia, quantified their native production levels and characterized their antibiotic activities against competingStaphylococcus aureus. We demonstrate that quinolone core methylation and position of unsaturation in the alkyl-chain dictate antibiotic potency which supports the proposed mechanism of action.
- B?ttcher, Thomas,Dieterich, Cora Lisbeth,Prothiwa, Michaela,Szamosvári, Dávid
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supporting information
p. 6328 - 6331
(2020/06/21)
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- Convergent Synthesis of Calcium-Dependent Antibiotic CDA3a and Analogues with Improved Antibacterial Activity via Late-Stage Serine Ligation
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A convergent synthesis via the late-stage serine ligation of naturally occurring calcium-dependent antibiotic CDA3a and its analogues has been developed, which allowed us to readily synthesize the analogues with the variation on the lipid tail. Some analogues were found to show 100-500-fold higher antimicrobial activity than the natural compound CDA3a against drug resistant bacteria. This study will enhance our understanding of CDA3a and provide valuable antibacterial lead candidates for further development.
- Blasco, Pilar,Chen, Delin,Chen, Sheng,Li, Xuechen,Po, Kathy Hiu Laam
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supporting information
(2020/06/29)
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- METHOD AND COMPOSITION FOR WATER TREATMENT
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The invention provides a method of microbial control in water comprising adding to the water one or more bromine-based biocide(s) and cis-2-decenoic acid or a salt thereof. Compositions in the form of liquid concentrates comprising bromine-based biocides and cis-2-decenoic acid or a salt thereof are also described.
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Page/Page column 18
(2020/12/11)
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- COMPOUND FOR USE AGAINST PATHOGENIC NEISSERIA AND HAEMOPHILUS SPECIES AND MORAXELLA CATARRHALIS
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The present invention relates to a compound, which can be used in the prevention and treatment of infections with pathogenic Neisseria species, in particular N. gonorrhoeae and N. meningitidis (the gonococcus and the meningococcus, respectively), and other pathogenic bacteria (e.g. Haemophilus species or Moraxella catarrhalis ), and which can be used for disinfecting a substrate from said bacteria. Moreover, the present invention relates to a corresponding pharmaceutical composition comprising said compound.
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- Unexpected AChE inhibitory activity of (2E)α,β-unsaturated fatty acids
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A small library of (E) α,β-unsaturated fatty acids was prepared, and 20 different saturated and mono-unsaturated fatty acids differing in chain length were subjected to Ellman's assays to determine their ability to act as inhibitors for AChE or BChE. While the compounds were only very weak inhibitors of BChE, seven molecules were inhibitors of AChE holding IC50 = 4.3–12.8 M with three of them as significant inhibitors of this enzyme. The results have shown trans 2-mono-unsaturated fatty acids are better inhibitors for AChE than their saturated analogs. Furthermore, the screening results indicate that the chain length is crucial for obtaining an inhibitory efficacy. The best results were obtained for (2E) eicosenoic acid (14) showing inhibition constants Ki = 1.51 ± 0.09 M and Ki′ = 7.15 ± 0.55 M. All tested compounds were mixed-type inhibitors with a dominating competitive part. Molecular modelling calculations indicate a different binding mode of active/inactive compounds for the enzymes AChE and BChE.
- Loesche, Anne,Wiemann, Jana,Al Halabi, Zayan,Karasch, Julia,Sippl, Wolfgang,Csuk, René
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supporting information
p. 3315 - 3319
(2018/09/17)
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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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- Synthesis of α,β-unsaturated aldehydes as potential substrates for bacterial luciferases
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Bacterial luciferase catalyzes the monooxygenation of long-chain aldehydes such as tetradecanal to the corresponding acid accompanied by light emission with a maximum at 490?nm. In this study even numbered aldehydes with eight, ten, twelve and fourteen carbon atoms were compared with analogs having a double bond at the α,β-position. These α,β-unsaturated aldehydes were synthesized in three steps and were examined as potential substrates in vitro. The luciferase of Photobacterium leiognathi was found to convert these analogs and showed a reduced but significant bioluminescence activity compared to tetradecanal. This study showed the trend that aldehydes, both saturated and unsaturated, with longer chain lengths had higher activity in terms of bioluminescence than shorter chain lengths. The maximal light intensity of (E)-tetradec-2-enal was approximately half with luciferase of P. leiognathi, compared to tetradecanal. Luciferases of Vibrio harveyi and Aliivibrio fisheri accepted these newly synthesized substrates but light emission dropped drastically compared to saturated aldehydes. The onset and the decay rate of bioluminescence were much slower, when using unsaturated substrates, indicating a kinetic effect. As a result the duration of the light emission is doubled. These results suggest that the substrate scope of bacterial luciferases is broader than previously reported.
- Brodl, Eveline,Ivkovic, Jakov,Tabib, Chaitanya R.,Breinbauer, Rolf,Macheroux, Peter
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p. 1487 - 1495
(2017/02/18)
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- An Unsaturated Quinolone N-Oxide of Pseudomonas aeruginosa Modulates Growth and Virulence of Staphylococcus aureus
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The pathogen Pseudomonas aeruginosa produces over 50 different quinolones, 16 of which belong to the class of 2-alkyl-4-quinolone N-oxides (AQNOs) with various chain lengths and degrees of saturation. We present the first synthesis of a previously proposed unsaturated compound that is confirmed to be present in culture extracts of P. aeruginosa, and its structure is shown to be trans-Δ1-2-(non-1-enyl)-4-quinolone N-oxide. This compound is the most active agent against S. aureus, including MRSA strains, by more than one order of magnitude whereas its cis isomer is inactive. At lower concentrations, the compound induces small-colony variants of S. aureus, reduces the virulence by inhibiting hemolysis, and inhibits nitrate reductase activity under anaerobic conditions. These studies suggest that this unsaturated AQNO is one of the major agents that are used by P. aeruginosa to modulate competing bacterial species.
- Szamosvári, Dávid,B?ttcher, Thomas
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supporting information
p. 7271 - 7275
(2017/06/13)
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- COMPOUNDS FOR USE AS AN ANTI-BACTERIAL OR ANTI-FUNGAL AGENT AND AS A ZINC SENSOR
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The present invention relates to a compound, which can be used as an anti-bacterial and/or an anti-fungal agent as well as a zinc sensor. Moreover, the present invention relates to a pharmaceutical composition comprising said compound and methods for treating bacterial or fungal infections in mammals.
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Paragraph 0114; 0115; 0116
(2018/01/18)
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- Allyl-Palladium-Catalyzed α,β-Dehydrogenation of Carboxylic Acids via Enediolates
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A highly practical and step-economic α,β-dehydrogenation of carboxylic acids via enediolates is reported through the use of allyl-palladium catalysis. Dianions underwent smooth dehydrogenation when generated using Zn(TMP)2?2 LiCl as a base in the presence of excess ZnCl2, thus avoiding the typical decarboxylation pathway of these substrates. Direct access to 2-enoic acids allows derivatization by numerous approaches.
- Zhao, Yizhou,Chen, Yifeng,Newhouse, Timothy R.
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supporting information
p. 13122 - 13125
(2017/09/13)
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- A Continuous, Fluorogenic Sirtuin 2 Deacylase Assay: Substrate Screening and Inhibitor Evaluation
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Sirtuins are important regulators of lysine acylation, which is implicated in cellular metabolism and transcriptional control. This makes the sirtuin class of enzymes interesting targets for development of small molecule probes with pharmaceutical potential. To achieve detailed profiling and kinetic insight regarding sirtuin inhibitors, it is important to have access to efficient assays. In this work, we report readily synthesized fluorogenic substrates enabling enzyme-economical evaluation of SIRT2 inhibitors in a continuous assay format as well as evaluation of the properties of SIRT2 as a long chain deacylase enzyme. Novel enzymatic activities of SIRT2 were thus established in vitro, which warrant further investigation, and two known inhibitors, suramin and SirReal2, were profiled against substrates containing ε-N-acyllysine modifications of varying length.
- Galleano, Iacopo,Schiedel, Matthias,Jung, Manfred,Madsen, Andreas S.,Olsen, Christian A.
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supporting information
p. 1021 - 1031
(2016/02/23)
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- Iron-catalyzed selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids by molecular oxygen
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Selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids was performed using O2 as the oxidant in the presence of a simple iron catalyst. The addition of an alkali metal carboxylate as a cocatalyst enhanced the selectivity for the desired product. Redox tuning of the iron catalyst via association with the alkali metal led to a controlled radical generation during the catalytic O2 oxidation.
- Tanaka, Shinji,Kon, Yoshihiro,Uesaka, Yumiko,Morioka, Ryo,Tamura, Masanori,Sato, Kazuhiko
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supporting information
p. 188 - 190
(2016/03/01)
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- MANUFACTURING METHOD OF α,β-UNSATURATED CARBOXYLIC ACID
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PROBLEM TO BE SOLVED: To provide a manufacturing method which can get α,β-unsaturated carboxylic acid at a high yield by liquid phase oxidation of α,β-unsaturated aldehyde by oxygen or air with a handy metal catalyst under a mild reaction condition. SOLUTION: Preferably under a presence of organic solvent, α,β-unsaturated carboxylic acid is manufactured by oxidation of α,β-unsaturated aldehydes and oxygen or air under a presence of an iron salt catalyst and a catalyst of alkali metal salt of carboxylic acid. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0040-0050
(2018/10/16)
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- Alpha, beta-unsaturated carbonyl compound production method
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The present invention relates to an alpha, beta-unsaturated carbonyl compound production method comprising the following steps: (1) oxidizing reaction of a primary alcohol with 3-20 carbon atoms under the effect of an oxidase for selective oxidation of a terminal alcoholic hydroxyl group into an aldehyde group to obtain an aldehyde group compound; (2) Reformatsky reaction of the aldehyde group compound and a halide under the catalytic effect of a metal to produce a corresponding alpha, beta-unsaturated carbonyl compound, the alpha, beta-unsaturated carbonyl compound production method is low-cost, less in environmental pollution, moreover, by alcohol oxidizing reaction by use of the oxidase, the quantitative and high selectivity corresponding alpha, beta-unsaturated carbonyl compound can be obtained, and the after processing is convenient.
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Paragraph 0059
(2016/11/21)
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- Characterization of FabG and FabI of the Streptomyces coelicolor dissociated fatty acid synthase
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Streptomyces coelicolor produces fatty acids for both primary metabolism and for biosynthesis of the secondary metabolite undecylprodiginine. The first and last reductive steps during the chain elongation cycle of fatty acid biosynthesis are catalyzed by FabG and FabI. The S. coelicolor genome sequence has one fabI gene (SCO1814) and three likely fabG genes (SCO1815, SCO1345, and SCO1846). We report the expression, purification, and characterization of the corresponding gene products. Kinetic analyses revealed that all three FabGs and FabI are capable of utilizing both straight and branched-chain β-ketoacyl-NAC and enoyl-NAC substrates, respectively. Furthermore, only SCO1345 differentiates between ACPs from both biosynthetic pathways. The data presented provide the first experimental evidence that SCO1815, SCO1346, and SCO1814 have the catalytic capability to process intermediates in both fatty acid and undecylprodiginine biosynthesis.
- Singh, Renu,Reynolds, Kevin A.
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p. 631 - 640
(2015/03/31)
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- Inhibition of human cytochrome P450 2E1 and 2A6 by aldehydes: Structure and activity relationships
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The purpose of this study was to probe active site structure and dynamics of human cytochrome P4502E1 and P4502A6 using a series of related short chain fatty aldehydes. Binding efficiency of the aldehydes was monitored via their ability to inhibit the binding and activation of the probe substrates p-nitrophenol (2E1) and coumarin (2A6). Oxidation of the aldehydes was observed in reactions with individually expressed 2E1, but not 2A6, suggesting alternate binding modes. For saturated aldehydes the optimum chain length for inhibition of 2E1 was 9 carbons (KI = 7.8 ± 0.3 μM), whereas for 2A6 heptanal was most potent (KI = 15.8 ± 1.1 μM). A double bond in the 2-position of the aldehyde significantly decreased the observed KI relative to the corresponding saturated compound in most cases. A clear difference in the effect of the double bond was observed between the two isoforms. With 2E1, the double bond appeared to remove steric constraints on aldehyde binding with KI values for the 5-12 carbon compounds ranging between 2.6 ± 0.1 μM and 12.8 ± 0.5 μM, whereas steric effects remained the dominant factor in the binding of the unsaturated aldehydes to 2A6 (observed KI values between 7.0 ± 0.5 μM and >1000 μM). The aldehyde function was essential for effective inhibition, as the corresponding carboxylic acids had very little effect on enzyme activity over the same range of concentrations, and branching at the 3-position of the aldehydes increased the corresponding KI value in all cases examined. The results suggest that a conjugated π-system may be a key structural determinant in the binding of these compounds to both enzymes, and may also be an important feature for the expansion of the active site volume in 2E1.
- Kandagatla, Suneel K.,Mack, Todd,Simpson, Sean,Sollenberger, Jill,Helton, Eric,Raner, Gregory M.
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p. 195 - 202
(2014/07/21)
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- A detailed identification study on high-temperature degradation products of oleic and linoleic acid methyl esters by GC-MS and GC-FTIR
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GC-MS and GC-FTIR were complementarily applied to identify oxidation compounds formed under frying conditions in methyl oleate and linoleate heated at 180 °C. The study was focused on the compounds that originated through hydroperoxide scission that remain attached to the glyceridic backbone in fats and oils and form part of non-volatile molecules. Twenty-one short-chain esterified compounds, consisting of 8 aldehydes, 3 methyl ketones, 4 primary alcohols, 5 alkanes and 1 furan, were identified. In addition, twenty non-esterified volatile compounds, consisting of alcohols, aldehydes and acids, were also identified as major non-esterified components. Furanoid compounds of 18 carbon atoms formed by a different route were also identified in this study. Overall, the composition of the small fraction originated from hydroperoxide scission provides a clear idea of the complexity of the new compounds formed during thermoxidation and frying.
- Berdeaux, Olivier,Fontagné, Stéphanie,Sémon, Etienne,Velasco, Joaquin,Sébédio, Jean Louis,Dobarganes, Carmen
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experimental part
p. 338 - 347
(2012/06/29)
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- Combined transition-metal- and organocatalysis: An atom economic C3 homologation of alkenes to carbonyl and carboxylic compounds
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A combination of regioselective room-temperature/ambient-pressure hydroformylation (transitionmetal catalysis) and decarboxylative Knoevenagel reactions (organocatalysis) allowed for the development of an efficient, one-pot C3 homologation of terminal alkenes to (E)-α,β-unsaturated acids and esters, (E)-β,γ-unsaturated acids, (E)-α-cyano acrylic acids, and α,β-unsaturated nitriles. All reactions proceed under mild conditions, tolerate a variety of functional groups, and furnish unsaturated carbonyl compounds in good yields and with excellent regioand stereocontrol. Further, an iterative C2 homologation of (E)-α,β-unsaturated carboxylic acids is possible through a combination of decarboxylative hydroformylation employing a supramolecular catalyst followed by decarboxylative Knoevenagel condensation with an organocatalyst.
- Kemme, Susanne T.,Smejkal, Tomas,Breit, Bernhard
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supporting information; experimental part
p. 3423 - 3433
(2010/06/21)
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- Stereoselective olefination reactions promoted by Rieke manganese
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A study of the advantages of using manganese, an inexpensive and nontoxic metal, to perform stereoselective β-elimination reactions and to promote sequential olefination reactions of aldehydes to obtain α,β- unsaturated esters and amides is presented. Various elimination reactions, all of them characterized by occurring with complete stereoselectivity and in high yields, were performed using active manganese (Mn*) as metalating agent. This ability of manganese has been applied to develop a novel and direct synthesis of (E)-α,β-unsaturated esters or amides and (Z)-α,β-unsaturated α-halo esters and α-choroamides through a Mn*-mediated sequential olefination protocol of aldehydes with dichloro esters or amides and trihalo esters or trichloroamides, respectively. Georg Thieme Verlag Stuttgart.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Del Amo, Vicente,Diaz, Pamela
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experimental part
p. 2634 - 2645
(2009/12/06)
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- Sequential reactions promoted by manganese: Completely stereoselective synthesis of (E)-α,β-unsaturated amides, ketones, aldehydes, and carboxylic acids
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(Chemical Equation Presented) A complete E-selective synthesis of α,β-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective β-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into α,β-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Diaz, Pamela
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p. 7974 - 7979
(2008/02/13)
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- Total structure and inhibition of tumor cell proliferation of laxaphycins
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From a mixed assemblage of Lyngbya majuscula rich marine cyanobacteria, we isolated a series of cell growth inhibitory cyclic peptides, The structures of the two major components, laxaphycins A (1) and B (2), and of two minor peptides, laxaphycins B2 (3) and B3 (4), were determined by spectroscopic methods and degradative analysis. Absolute configurations of natural and nonproteinogenic amino acids were determined by a combination of hydrolysis, synthesis of noncommercial residues, chemical derivatization, and HPLC analysis. The organism producing the laxaphycins was identified as the cyanobacterium Anabaena torulosa. The antiproliferative activity of laxaphycins was investigated on a panel of solid and lymphoblastic cancer cells. Our results demonstrate that in contrast to laxaphycin A, laxaphycin B inhibits the proliferation of sensitive and resistant human cancer cell lines and that this activity is strongly increased in the presence of laxaphycin A. This effect appears to be due to an unusual biological synergism.
- Bonnard, Isabelle,Rolland, Marc,Salmon, Jean-Marie,Debiton, Eric,Barthomeuf, Chantal,Banaigs, Bernard
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p. 1266 - 1279
(2007/10/03)
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- Direct reaction of dibromoacetic acid with aldehydes promoted by samarium diiodide: An easy, efficient, and rapid synthesis of (E)-α,β- unsaturated carboxylic acids with total stereoselectivity
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A promoted SmI2 direct reaction of dibromoacetic acid with different aldehydes, followed by an elimination reaction also promoted by samarium diiodide, affords (E)-α,β-unsaturated carboxylic acids 2 with total stereoselectivity. A mechanism to explain this transformation is proposed.
- Concellon, Jose M.,Concellon, Carmen
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p. 1728 - 1731
(2007/10/03)
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- Synthesis of the antibiotic (R)-reutericyclin via Dieckmann condensation
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(R)-Reutericyclin ((R)-1), a bactericidal, amphiphilic natural product with a trisubstituted tetramic acid moiety, was prepared in four steps from D-leucine in anoverall yieldof 24%. The chiral heterocyclic portion of 1 was synthesized by Dieckmann cyclization of ethyl N-(acetoacetyl)leucinate (7), and the resulting pyrrole derivative 8 was N-acylated with (E)-dec-2-enoyl chloride in the presence of BuLi at-70° (Scheme2). This new procedure is straightforward and allows the synthesis of both antipodes of reutericyclin in anenantiomeric excess (ee) of ca. 80%.
- Boehme, Roswitha,Jung, Guenther,Breitmaier, Eberhard
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p. 2837 - 2841
(2007/10/03)
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- INHIBITORS OF YEAST FILAMENTOUS GROWTH AND METHOD OF THEIR MANUFACTURE
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The invention broadly relates to the use of α, β-unsaturated fatty acids to inhibit the filamentous growth of fungi and yeasts and to a method for producing same. In particular the invention relates to the use of optionally substituted C8 to C15 α, β-unsaturated fatty acids or salts, esters or amides thereof for inhibiting or retarding the yeast-to-mycelium transition of organisms having a dimorphic life cycle.
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Page/Page column 12-14
(2008/06/13)
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- TMS Triflate-Catalyzed Cleavage of Prenyl (3-Methylbut-2-enyl) Ester
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(Matrix Presented) Prenyl (3-methylbut-2-enyl) ester is catalytically cleaved by TMS triflate affording carboxylic acid and isoprene in high yield under mild conditions with high chemoselectivity without causing epimerization of the neighboring chiral cen
- Nishizawa, Mugio,Yamamoto, Hirofumi,Seo, Ken,Imagawa, Hiroshi,Sugihara, Takumichi
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p. 1947 - 1949
(2007/10/03)
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- KOH-promoted reaction of C,O,O-tris(trimethylsilyl) ketene acetal with aldehydes: Practical and easy access to (E)-α,β-ethylenic carboxylic acids
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The use of a catalytic amount of KOH has been found to be very efficient in promoting reaction of silylketene acetal 1 with aldehydes 2 to afford the corresponding (E)-α,β-ethylenic carboxylic acids 3 under very mild conditions.
- Lensen,Mouelhi,Bellassoued
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p. 1007 - 1011
(2007/10/03)
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- Two-carbon homologation of aldehydes via silyl ketene acetals. 2. Study of the stereochemical control in the formation of (E)-alkenoic acids
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The condensation of C,O,O-tris(trimethylsilyl)ketene acetal 1 with aldehydes 2 in the presence of catalytic amounts of mercuric iodide at room temperature affords syn and anti β-trimethylsiloxy α-trimethylsilyl alkanoic acid silyl esters 3 in good yields. These new compounds gave, under acidic or basic conditions, E and (or) Z enoic acids 4. The paths for the formation of these alkenoic acids are discussed.
- Bellassoued,Mouelhi,Lensen
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p. 5054 - 5057
(2007/10/03)
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- Electrochemical selective incorporation of CO2 into terminal alkynes and diynes
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Electrochemical incorporation of CO2 into terminal alkynes and diynes on silver cathodes occurred selectively, to afford monocarboxylic acid derivatives in good yields. The electrolyses were carried out in one-compartment cells fitted with magnesium anodes, under mild conditions.
- Ko?ster, Frank,Dinjus, Erkhardt,Din?ach, Elisabet
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p. 2507 - 2511
(2007/10/03)
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- Racemic synthesis of the new antibiotic tetramic acid reutericyclin
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The synthesis of the new bacteriocidal compound reutericyclin, 3-acetyl-1-(2-trans-decenoyl)-2-hydroxy-5-isobutyl-Δ2-pyrrolin- 4-one, is performed by coupling of N-(2-trans-decenoyl)-L-leucine to Meldrum's acid followed by cyclization. The resulting N-acylated tetramic acid is directly C-acetylated in position 3. HPLC-purification on RP-C18 gave racemic reutericyclin in high purity. 2D-NMR and FT-ICR-MS data are identical with those of natural reutericyclin.
- Marquardt,Schmid,Jung
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p. 1131 - 1132
(2007/10/03)
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- Experimental and computational studies on substituent effects in reactions of peracid-aldehyde adducts
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Liquid phase oxidation of six branched and four linear aldehydes by dioxygen and m-chloroperbenzoic acid was studied experimentally. 2-Substituted (α-branched) aldehydes reacted to give formates (via Bayer-Villiger mechanism) whereas the related linear saturated aldehydes were converted to the corresponding carboxylic acids. Formation of both these products can be rationalized via rearrangement reactions of peracid-aldehyde adducts 1. Computational studies employing DFT methods at the DNPP level with the Spartan program (v5.0) were carried out in order to understand properties of those adducts. Conformational properties of the adducts 1 were found to shed light on the differences observed in the reactions of linear and branched adducts. (C) 2000 Elsevier Science Ltd.
- Lehtinen, Christel,Nevalainen, Vesa,Brunow, G?sta
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p. 9375 - 9382
(2007/10/03)
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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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- Synthesis of the Substituted Z-1-Bromo-1-alkenes and Arylacetylenes from 2,3-Dibromocarboxylic Acids
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Stereoselectivity was studied of simultaneous debromination-decarboxylation of dibrominated cinnamic and acrylic acids. The best selectivity in formation of Z-vinyl bromides was achieved with the use of organic nitrogen bases. The 1-bromo-1-alkenes were converted into the corresponding acetylenes.
- Matveeva,Erin,Kurz
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p. 1065 - 1067
(2007/10/03)
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- A versatile and convenient protocol for the stereocontrolled synthesis of olefinic insect pheromones
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A combination of the Horner-Emmons synthesis of alkyl 2,4-dienoates with their hydrogenation over complex L·Cr(CO)3 catalysts (L = 3CO or arene) provides a versatile, stereocontrolled and operationally simple approach to the (Z)-disubstituted, (Z)-trisubstituted, (E)-trisubstituted alkenes and skipped (Z,Z)-disubstituted diolefins with a homoallylic type of function. This protocol, sometimes supplemented by an enzymatic hydrolysis, was successfully applied to the synthesis of configurationally pure (gp ≥ 98%) pheromones of the furniture carpet beetle, dry bean beetle, rusty grain beetle, square-necked grain beetle and of a trail-following pheromone mimic for subterranean termites
- Vasil'ev, Andrei A.,Vlasyuk, Alexei L.,Gamalevich, Galina D.,Serebryakov, Edward P.
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p. 389 - 400
(2007/10/03)
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- Monocyclic Rod-Type Liquid Crystals, 2-(2-Alkenoyloxy)-5-alkoxytropones
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In 2-(2-alkenoyloxy)-5-alkoxytropones, showing a monotropic smectic A phase, the introduction of a double bond lowers the melting and clearing points as well as the recrystallization temperatures.
- Mori, Akira,Mori, Ryoji,Takeshita, Hitoshi
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p. 1795 - 1796
(2007/10/02)
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- PALLADIUM MEDIATED SYNTHESIS OF CONJUGATED E or Z ENONES AND UNSYMMETRICAL DIVINYL KETONES. ONE-POT PREPARATION OF ISOEGOMAKETONE
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The palladium (o) catalyzed coupling of acyl halides or anhydrides with alkenyl copper reagents furnishes α,β ethylenic ketones and α,β-α',β' diethylenic ketones in high yield.The substitution pattern of the alkenyl copper reagent, directly obtained by carbocupration of alkynes, is fully retained.Anhydrides of Z-ethylenic acids also retain their Z stereochemistry. β-halogeno-vinyl ketones react under the above conditions to afford α,β-γ,δ dienones.An efficient one-pot synthesis of Z or E isoegomaketone is reported.
- Jabri, N.,Alexakis, A.,Normant, J. F.
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p. 1369 - 1380
(2007/10/02)
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- A NEW ALKAMIDE FROM PIPER SYLVATICUM
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Sylvamide, a new amide derivative, has been isolated from the petrol extract of the seeds of Piper sylvaticum (Roxb.).From spectral and chemical studies its structure has been elucidated as N-isobutyl-4,5-dihydroxy-2(E)-decenamide. - Key Word Index: Piper sylvaticum; Piperaceae; seeds; sylvamide; N-isobutyl-4,5-dihydroxy-2(E)-decenamide.
- Banerji, Avijit,Pal, Sudhir Chandra
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p. 1321 - 1324
(2007/10/02)
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