- An Efficient Synthesis of Natural Tribolure
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An efficient synthesis of natural tribolure has been achieved through an asymmetric methylation as a key step. Natural tribolure is a mixture of four stereoisomers, so racemic 2-methylbutan-1-ol was used as starting material. After a C5+C4 strategy and then a mixed Evan’s template inductive methylation, the key intermediate was obtained. Finally, the natural product tribolure (4:4:1:1 of stereoisomers, respectively) was obtained in 10 linear steps and in 34.2% overall yield.
- Shi, Jianmin,Liu, Lu,Tang, Meng,Zhang, Tao,Bai, Hongjin,Du, Zhenting
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- Isolation and synthesis of caprolactins A and B, new caprolactams from a marine bacterium
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Two new caprolactams have been isolated from an unidentified Gram-positive bacterium obtained from a deep-ocean sediment sample. Caprolactins A (1) and B (2), which were obtained as an inseparable mixture, are composed of cyclic-L-lysine linked to 7-methyloctanoic acid and 6-methyloctanoic acid, respectively. The structures were proposed using spectroscopic methods and confirmed by synthesis. Both caprolactins A and B are cytotoxic towards human epidermoid carcinoma (KB) cells and human colorectal adenocarcinoma (LoVo) cells and exhibit antiviral activity towards Herpes simplex type II virus.
- Davidson,Schumacher
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- Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: Application of 1JC,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites
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Chemical investigation of secondary metabolites from a marine-derived actinomycete strain of the genus Kocuria, isolated from a stony coral Mycedium sp., led to the identification of two new alkanoylimidazoles, nocarimidazoles C (1) and D (2) as well as three known congeners, nocarimidazoles A (3) and B (4) and bulbimidazole A (5). Structure analysis of 1 and 2 by NMR and MS revealed that both are 4-alkanoyl-5-aminoimidazoles with a 6-methyloctanoyl or decanoyl chain, respectively. Two possible positions of the amino group on the imidazole rings (C-2 and C-5) posed a challenge in the structure study, which was settled by the measurement of 1JC,H coupling constants for comparison with those of synthetically prepared model imidazoles. The absolute configurations of the anteisoalkanoyl group present in 1, 4, and 5 were determined by low-temperature HPLC analysis of the degradation products labeled with a chiral anthracene reagent, which revealed that 1 is a mixture of the R- and S-enantiomers with a ratio of 73:27, 4 is the pure (S)-enantiomer, and 5 is the (S)-enantiomer with 98% ee. The present study illustrates the diversity in the stereochemistry of anteiso branching in bacterial metabolites. Compounds 1-4 were moderately antimicrobial against Gram-positive bacteria and fungi, with MIC ranges of 6.25-25 μg/mL.
- Akasaka, Kazuaki,Harunari, Enjuro,Igarashi, Yasuhiro,Karim, Rokon Ul,Oku, Naoya,Sharma, Amit Raj,Sibero, Mada Triandala,Urabe, Daisuke
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p. 2719 - 2727
(2020/12/01)
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- PEPTIDE ANTIBIOTICS
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There is provided a range of novel compounds. These novel compounds may demonstrate a broad spectrum antibacterial and antifungal activity. These compounds may be active against the emerging polymyxin resistant bacteria. These compounds may also be useful
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Paragraph 00194
(2019/05/22)
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- Synthesis and Bioactivity Investigation of the Individual Components of Cyclic Lipopeptide Antibiotics
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In this paper, 26 natural polymyxin components and a new derivative S2 were synthesized, and their differences in efficacy and toxicity have been investigated. Almost all of the synthesized components showed strong activity against both susceptible and resistant strains of E. coli, K. pneumoniae, P. aeruginosa, and A. baumannii. The toxicities were obviously different between the components. Only some of the components were tested for toxicity in vivo. Compounds E2, E2-Val, A2, M2, D2, and S2 showed obviously lower renal cytotoxicity and acute toxicity than polymyxins B and E. The in vivo nephrotoxicity of E2, M2, and S2 was similar to that of polymyxin E. Compound S2, with four positive charges, was especially interesting as it possessed both increased efficacy and decreased toxicity. The SAR and toxicity studies indicated that further structural modification could concentrate on polymyxin S. The results also indicated that S2 could be a new drug candidate.
- Cui, A-Long,Hu, Xin-Xin,Gao, Yan,Jin, Jie,Yi, Hong,Wang, Xiu-Kun,Nie, Tong-Ying,Chen, Yang,He, Qi-Yang,Guo, Hui-Fang,Jiang, Jian-Dong,You, Xue-Fu,Li, Zhuo-Rong
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p. 1845 - 1857
(2018/03/21)
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- A Highly Convergent Total Synthesis of Leustroducsin B
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Leustroducsin B exhibits a large variety of biological activities and unique structural features. An efficient and highly convergent total synthesis of Leustroducsin B was achieved in 17 longest linear and 39 total steps by disconnecting the molecule into three fragments having similar levels of complexity. These pieces were connected via a highly efficient chelate-controlled addition of a vinyl zincate to an α-hydroxy ketone and a silicon-mediated cross-coupling. The stereochemistry of the central and western fragments was set catalytically in high yields and excellent de by a zinc-ProPhenol-catalyzed aldol reaction and a palladium-catalyzed asymmetric allylic alkylation.
- Trost, Barry M.,Biannic, Berenger,Brindle, Cheyenne S.,O'Keefe, B. Michael,Hunter, Thomas J.,Ngai, Ming-Yu
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p. 11594 - 11597
(2015/09/28)
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- Method for Producing Isononanoic Acid Esters, Starting from 2-Ethyl Hexanol
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A Process for preparing carboxylic esters of a mixture of structurally branched C9 monocarboxylic acids proceeding from 2-ethylhexanol is characterized in that (a) 2-ethylhexanol is dehydrated to an octene mixture in the presence of a catalyst; (b) the octene mixture obtained in step a) is reacted in the presence of a transition metal compound of group VIII of the periodic table of the elements with carbon monoxide and hydrogen to give a mixture of isomeric isononanals; (c) the mixture of isomeric isononanals obtained in step b) is oxidized to a mixture of structurally branched C9 monocarboxylic acids; and (d) the mixture of structurally branched C9 monocarboxylic acids obtained in step c) is reacted with alcohols to give carboxylic esters.
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Paragraph 0081-0087
(2015/06/17)
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- Method for Producing Isononanoic Acids from 2-Ethyl Hexanol
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Process for preparing isononanoic acid proceeding from 2-ethylhexanol, characterized in that (a) 2-ethylhexanol is dehydrated to octene in the presence of a catalyst; (b) the octene obtained in step a) is reacted in the presence of a transition metal compound of group VIII of the periodic table of the elements with carbon monoxide and hydrogen to give isononanal; and (c) the isononanal obtained in step b) is oxidized to isononanoic acid.
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Paragraph 0062-0071
(2015/07/15)
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- Studies on tridecaptin B1, a lipopeptide with activity against multidrug resistant Gram-negative bacteria
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Previously other groups had reported that Paenibacillus polymyxa NRRL B-30507 produces SRCAM 37, a type IIA bacteriocin with antimicrobial activity against Campylobacter jejuni. Genome sequencing and isolation of antimicrobial compounds from this P. polymyxa strain show that the antimicrobial activity is due to polymyxins and tridecaptin B1. The complete structural assignment, synthesis, and antimicrobial profile of tridecaptin B1 is reported, as well as the putative gene cluster responsible for its biosynthesis. This peptide displays strong activity against multidrug resistant Gram-negative bacteria, a finding that is timely to the current problem of antibiotic resistance.
- Cochrane, Stephen A.,Lohans, Christopher T.,Van Belkum, Marco J.,Bels, Manon A.,Vederas, John C.
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p. 6073 - 6081
(2015/06/08)
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- Nocapyrones: α- and γ-pyrones from a marine-derived Nocardiopsis sp
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One new α-pyrone (nocapyrone R (1)), and three known γ-pyrones (nocapyrones B, H and L (2-4)) were isolated from the culture extract of a Nocardiopsis strain collected from marine sediment. Structures of these compounds were determined on the basis of spectroscopic data including NMR and MS. γ-Pyrones 2-4 were found to induce adiponectin production in murine ST-13 preadipocyte cells but the α-pyrone 1 had no activity. The absolute configuration of the anteiso-methyl branching in 4 was determined by HPLC comparison of a degraded product of 4 with standard samples as a 2:3 enantiomeric mixture of (R)- and (S)-isomers.
- Kim, Youngju,Ogura, Hiromu,Akasaka, Kazuaki,Oikawa, Tsutomu,Matsuura, Nobuyasu,Imada, Chiaki,Yasuda, Hisato,Igarashi, Yasuhiro
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p. 4110 - 4125
(2014/12/10)
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- Asymmetric synthesis and absolute configuration of streptophenazine G
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The asymmetric synthesis of the antibacterial natural product, streptophenazine G, has been achieved by employing asymmetric alkylation and asymmetric aldol reactions using chiral oxazolidinones as the key steps. The originally proposed structure for streptophenazine G has been revised, and its absolute configuration has been determined to be 1′S,2′R,6′S. The asymmetric total synthesis of 6′-epi-streptophenazine G is also described.
- Yang, Zhicai,Jin, Xiaomin,Guaciaro, Michael,Molino, Bruce F.
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experimental part
p. 3191 - 3196
(2012/05/19)
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- PRODUCTION METHOD OF CAPSINOID BY DEHYDRATING CONDENSATION, STABILIZING METHOD OF CAPSINOID, AND CAPSINOID COMPOSITION
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In the production methods of capsinoid by esterification using an enzyme, a method of conveniently obtaining capsinoid in a high yield in a short time without using a dehydrating agent is provided. In addition, a method of stable preservation of produced capsinoid by purifying the obtained capsinoid under stable conditions is provided. A fatty acid represented by the formula (1) and a hydroxymethylphenol represented by the formula (2) are condensed without solvent or in a low-polar solvent, using an enzyme as a catalyst to give an ester compound represented by the formula (3). In addition, a fatty acid represented by the formula (4) is added to the ester compound represented by the formula (3) for stabilization. wherein each symbol is as defined in the specification.
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Page/Page column 51
(2008/06/13)
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- Volatile lactones - (5S,S)-5-methyl-3-(methylalkyl)furan-2(5H)-ones - Identified in the submerged cultivation of Streptomyces avermitilis
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Six new compounds have been identified in the volatile fractions produced during the submerged cultivation of Streptomyces avermitilis. By recording the GC/MS, GC/FTIR, CD, 1H and 13C NMR data and by performing chemical degradation experiments, these compounds were determined to be (5S,S)-5-methyl-3-(methylalkyl)furan-2(5H)-ones. Herein, the existence of volatile lactones with an anteiso structure of the side-chain is thus documented for the first time. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Rezanka, Tomas,Sigler, Karel
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p. 4277 - 4284
(2007/10/03)
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- Chemical transformation of Leustroducsins: Synthesis of Leustroducsin B
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Chemical transformation of Leustroducsin H to Leustroducsin B has been successfully accomplished in 11 steps including enzymatic hydrolysis of phosphate ester. The process described here enables to differentiate all hydroxyl groups, amino and phosphate fu
- Matsuhashi, Hayao,Shimada, Kousei
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p. 5619 - 5626
(2007/10/03)
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- Enatiomeric separation of branched fatty acids after conversion with trans-2-(2,3-Anthracenedicarboximido)cyclohexanol, a highly sensitive chiral fluorescent conversion reagent
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(1R,2R)-2-(2,3-Anthracenedicarboximido)cyclohexanol was synthesized as a highly sensitive chiral fluorescent conversion reagent. The diastereomeric derivatives of chiral branched fatty acids that had methyl ethyl chirality from the 2 to 12 position were separated into 2 peaks by reversed-phase HPLC and detected at the 10-15 mole level by fluorometry.
- Akasaka, Kazuaki,Ohrui, Hiroshi
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p. 1209 - 1215
(2007/10/03)
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- Enantiomeric separation of carboxylic acids having chiral centers remote from the carboxyl group by labelling with a chiral fluorescent derivatization reagent
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Enantiomeric separations of 2-, 3-, 4-, 5- and 6-methyl fatty acids and 3-, 4- and 5-hydroxy fatty acids derivatized with (S) -(+)-2-(anthracene-2,3-dicarboximido)-1 propyl trifluoromethanesulfonate are described. Although there are 4-8 bond distances between the chiral centers of these diastereomeric derivatives, they are separated on HPLC and detected at fmol levels.
- Akasaka, Kazuaki,Meguro, Hiroshi,Ohrui, Hiroshi
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p. 6853 - 6856
(2007/10/03)
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