76835-67-1Relevant academic research and scientific papers
A Unique Combination of Two Different Quorum Sensing Systems in the β-Rhizobium Cupriavidus taiwanensis
Wakimoto, Takayuki,Nakagishi, Shiori,Matsukawa, Nao,Tani, Shuji,Kai, Kenji
supporting information, p. 1876 - 1884 (2020/07/06)
Cupriavidus taiwanensis LMG19424, a β-rhizobial symbiont of Mimosa pudica, harbors phc and tqs quorum sensing (QS), which are the homologous cell-cell communication systems previously identified from the plant pathogen Ralstonia solanacearum and the human pathogen Vibrio cholerae, respectively. However, there has been no experimental evidence reported that these QS systems function in C. taiwanensis LMG19424. We identified (R)-methyl 3-hydroxymyristate (3-OH MAME) and (S)-3-hydroxypentadecan-4-one (C15-AHK) as phc and tqs QS signals, respectively, and characterized these QS systems. The expression of the signal synthase gene phcB and tqsA in E. coli BL21(DE3) resulted in the high production of 3-OH MAME and C15-AHK, respectively. Their structures were elucidated by comparison of EI-MS data and GC/chiral LC retention times with synthetic standards. The deletion of phcB reduced cell motility and increased biofilm formation, and the double deletion of phcB/tqsA caused the accumulation of the metal chelator coproporphyrin III in its mutant culture. Although the deletion of phcB and tqsA slightly reduced its ability to nodulate on aseptically grown seedlings of M. pudica, there was no significant difference in nodule formation between LMG19424 and its QS mutants when commercial soils were used. Taken together, this is the first example of the simultaneous production of 3-OH MAME/C15-AHK as QS signals in a bacterial species, and the importance of the phc/tqs QS systems in the saprophytic stage of C. taiwanensis LMG19424 is suggested.
Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group
Cai, Li,Emmanuel, Khalisha A.,Gao, Qi,Ge, Dongmian,Han, Ziyi,Li, Gen,McManus, Cynthia L.,Sui, Qiang,Xue, Jundi
supporting information, p. 1955 - 1962 (2020/10/02)
Lipid A, the hydrophobic domain of lipopolysaccharide (LPS), is a strong immunostimulator and therefore a valuable target for the development of novel immunomodulators. Various lipid A derivatives have been chemically synthesized in order to reduce toxicity while retaining the immunostimulatory activity. In this work, we describe a novel approach to the frequently problematic synthesis of monophosphorylated mono- and disaccharide lipid X using a combination of established chemistry and a novel 2-naphthyl-methyl ether (Nap) protecting group for “permanent” protection of hydroxy groups. Of particular note is the fact that the key Nap protecting group is able to remain in the molecule until the final global deprotection step. Our synthetic strategy is not only efficient in regards to the yield of the various chemical transformations, but also robust in regards to the potential application of this route to the production of other lipid A analogs.
Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
Lin, Zechao,Li, Jiahong,Huang, Qingfei,Huang, Qiuya,Wang, Qiwei,Tang, Lei,Gong, Deying,Yang, Jun,Zhu, Jin,Deng, Jingen
, p. 4419 - 4429 (2015/05/13)
A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity. (Chemical Equation Presented).
Enantioselective synthesis of 3-hydroxytetradecanoic acid and its methyl ester enantiomers as new antioxidants and enzyme inhibitors
Kuecuek, Hatice Baspinar,Yusufoglu, Ayse
, p. 1087 - 1091 (2013/07/26)
Optically pure R and S enantiomers of 3-hydroxytetradecanoic acid and its methyl esters were synthesised by porcine pancreas lipase catalysed hydrolysis of racemic methyl 3-hydroxytetradecanoate in aqueous medium, with the aim of determining their antioxidant, antielastase and antiurease activities. The effects of the weight ratio of substrate/lipase and the reaction time were investigated. Optimum reaction conditions were determined. The resolution reaction with porcine pancreas lipase afforded (R)-3-hydroxytetradecanoic acid, which is a component of bacterially important lipid A, with greater than 99 % ee in excellent enantiomeric ratio (>900) after 7 h incubation with a substrate/lipase weight ratio of 3:1 and 43 % conversion of the substrate. Methyl (S)-3-hydroxytetradecanoate, which is the unreacted enantiomer of the racemic substrate, could be recovered with 98 % ee after 7 h resolution with a substrate/lipase weight ratio of 1:1 and 60 % conversion. (R)-3- Hydroxytetradecanoic acid was converted to its ester and the S methyl ester to its acid. This biocatalytic enantioselective resolution in aqueous medium presents an environmentally friendly and green chemistry method for the synthesis of R and S enantiomers of 3-hydroxytetradecanoic acid and its methyl esters.
Asymmetric synthesis of long chain β-hydroxy fatty acid methyl esters as new elastase inhibitors
Hasdemir, Belma,Onar, Huelya Elik,Yusufolu, Aye
, p. 1100 - 1105 (2012/11/07)
Herein, β-hydroxy methyl esters with an even carbon chain length of 12-20 1b-5b were synthesized by three different asymmetric reduction methods I, II III from their corresponding β-keto methyl esters 1a-5a with the aim of determining their elastase activities. In method I, chiral catalyst A was prepared from chiral ligand (R)-binaphthol 1, while in method II, chiral catalyst B was synthesized from (2R,3R)-diisopropyl tartrate 2. Chiral catalyst B has not previously been used in asymmetric borane reductions or in the asymmetric synthesis of chiral β-hydroxy methyl esters. In method III, an asymmetric reduction was catalysed by (R)-Me-CBS oxazaborolidine 3. Hydride transfer was carried out in all of these methods by BH3· SMe2. Chiral hydroxy methyl esters with an (S)-configuration were synthesized by method I and with an (R)-configuration via methods II and III. The chiral hydroxy methyl esters obtained were analysed by chiral HPLC for their ee % values. Methods I, II and III were applied to long chain β-keto methyl esters for the first time. The reduction methods I, II and III were examined in terms of reaction yield and enantiomeric excess according to carbon chain length and the variable ratio of chiral catalysts to β-keto methyl ester. The highest enantiomeric excess of 90% ee was found in method III for 12 and 14 carbon numbers.
Asymmetric synthesis of tetrahydrolipstatin and valilactone
Case-Green, Stephen C.,Davies, Stephen G.,Roberts, Paul M.,Russell, Angela J.,Thomson, James E.
experimental part, p. 2620 - 2631 (2009/04/06)
The highly diastereoselective aldol reaction between acyl complexes of the iron chiral auxiliary [(η5-C5H5)Fe(CO)(PPh3)] and β-hydroxy aldehydes (obtained via a Noyori asymmetric hydrogenation), followed by a tandem oxidative decomplexation-cyclisation process gives access to β-substituted and α,β-disubstituted β-lactones in high ee. This methodology has been employed in the asymmetric syntheses of tetrahydrolipstatin and valilactone.
Chemical synthesis of a glycolipid library by a solid-phase strategy allows elucidation of the structural specificity of immunostimulation by rhamnolipids
Bauer, Joerg,Brandenburg, Klaus,Zaehringer, Ulrich,Rademann, Joerg
, p. 7116 - 7124 (2007/10/03)
The first synthesis of a glycolipid library by hydrophobically assisted switching phase (HASP) synthesis is described. HASP synthesis enables flexible switching between solution-phase steps and solid-supported reactions conducted with molecules attached to a hydrophobic silica support. A library of glycolipids derived from the lead compound 1 - a strongly immunostimulatory rhamnolipid - with variations in the carbohydrate part, the lipid components, and the stereochemistry of the 3-hydroxy fatty acids was designed and synthesized. The enantiose lective synthesis of the 3-hydroxy fatty acid building blocks was achieved by employing asymmetric hydrogenation of 3-oxo fatty acids. Glycolipids were prepared by this approach without any intermediary isolation steps, mostly in excellent yields. Final deprotection to the carboxylic acids was accomplished by enzymatic ester cleavage. All prepared rhamnolipids were tested for their immunostimulatory properties against human monocyte cells by assaying the secretion of the cytokine tumor necrosis factor α (TNFα) into the medium. The observed structure-activity relationships of rhamnolipids indicate a specific, recognition-based mode of action, with small structural variations in the rhamnolipids resulting in strong effects on the immunostimulatory activities of the rhamnolipids at low micromolar concentrations.
Enantioselective synthesis of α-amino acids from N-tosyloxy β-lactams derived from β-keto esters
Durham, Timothy B.,Miller, Marvin J.
, p. 27 - 34 (2007/10/03)
A novel synthetic sequence has been developed to convert simple β-keto esters into enantiomerically enriched α-amino acids. The key features of this sequence include the addition of azide to the C3 position of β-keto ester derived N-tosyloxy-β-lactams through a concomitant nucleophilic addition/N-O bond reduction reaction, a mild CsF-induced N1 benzylation of α-azido monocyclic β-lactams, the preparation of α-keto-β-lactams through a novel four-step sequence from the corresponding 3-azido-1-benzyl-β-lactams, and TEMPO-mediated ring expansion of these compounds to the corresponding N-carboxy anhydrides (NCAs). In addition, the synthesis, isolation, and characterization of unusual 3-imino and 3-chloramino-β-lactams is reported.
Enzymatic preparation of (S)-3-hydroxytetradecanoic acid and synthesis of unnatural analogues of lipid A containing the (S)-acid
Liu, Wen-Chi,Oikawa, Masato,Fukase, Koichi,Suda, Yasuo,Winarno, Hendig,Mori, Saeko,Hashimoto, Masahito,Kusumoto, Shoichi
, p. 1441 - 1450 (2007/10/03)
Synthesis of unnatural analogues, that contain (S)-3-hydroxytetradecanoyl moieties in place of the corresponding natural (R)-isomers, of both lipid A and its biosynthetic precursor, designated precursor Ia or lipid IV(A), has been achieved through our recently developed procedure. (S)-3-Hydroxytetradecanoic acid was prepared from its racemate through the optical resolution by the use of a lipase and subsequent fractional recrystallization. The (S)-acyl analogue of lipid A exhibited slightly stronger interleukin-6 inducing activity than the corresponding natural lipid A, and the (S)-acyl analogue of the biosynthetic precursor was far more active than the natural precursor in inhibiting the induction of interleukin-6 by lipopolysaccharide.
Optically active phosphorous compounds
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, (2008/06/13)
The present invention is concerned with novel optically active phosphorus compounds of the general formula STR1 wherein R and R1 each independently signify hydroxy, a protected hydroxy group, lower alkyl or lower alkoxy and R2 to R5 each independently signify alkyl with 3 to 7 carbon atoms, cycloalkyl or aryl or R2 and R3 or R4 and R5 together with the phosphorus form a group of the formula STR2 wherein R2 and R3 are different when R4 and R5 are the same, and R4 and R5 are different when R2 and R3 are the same, the manufacture of such compounds, their use for enantioselective reactions, such as, e.g., asymmetric hydrogenations, enantioselective hydrogen displacements in prochiral allylic systems and the like, as well as complexes of the compounds of formula I with Group VIII metals.
