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Beilstein Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/28781710/mechanochemical-synthesis-of-graphene-oxide-supported-transition-metal-catalysts-for-the-oxidation-of-isoeugenol-to-vanillin
#1
Ana Franco, Sudipta De, Alina M Balu, Araceli Garcia, Rafael Luque
Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc.) have been effectively used in the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28781709/a-new-member-of-the-fusaricidin-family-structure-elucidation-and-synthesis-of-fusaricidin-e
#2
Marcel Reimann, Louis P Sandjo, Luis Antelo, Eckhard Thines, Isabella Siepe, Till Opatz
Two hitherto unknown fusaricidins were obtained from fermentation broths of three Paenibacillus strains. After structure elucidation based on tandem mass spectrometry and NMR spectroscopy, fusaricidin E was synthesized to confirm the structure and the suggested stereochemistry. The synthesis was based on a new strategy which includes an efficient access to the 15-guanidino-3-hydroxypentadecanoyl (GHPD) side chain from erucamide.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694868/aqueous-semisynthesis-of-c-glycoside-glycamines-from-agarose
#3
Juliana C Cunico Dallagnol, Alexandre Orsato, Diogo R B Ducatti, Miguel D Noseda, Maria Eugênia R Duarte, Alan G Gonçalves
Agarose was herein employed as starting material to produce primary, secondary and tertiary C-glycoside glycamines, including mono- and disaccharide structures. The semisynthetic approach utilized was generally based on polysaccharide-controlled hydrolysis followed by reductive amination. All reactions were conducted in aqueous media and without the need of hydroxyl group protection. We were able to identify optimal conditions for the reductive amination of agar hydrolysis products and to overcome the major difficulties related to this kind of reaction, also extending it to reducing anhydrosugars...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694867/sugar-based-micro-mesoporous-hypercross-linked-polymers-with-in-situ-embedded-silver-nanoparticles-for-catalytic-reduction
#4
Qing Yin, Qi Chen, Li-Can Lu, Bao-Hang Han
Porous hypercross-linked polymers based on perbenzylated monosugars (SugPOP-1-3) have been synthesized by Friedel-Crafts reaction using formaldehyde dimethyl acetal as an external cross-linker. Three perbenzylated monosugars with similar chemical structure were used as monomers in order to tune the porosity. These obtained polymers exhibit microporous and mesoporous features. The highest Brunauer-Emmett-Teller specific surface area for the resulting polymers was found to be 1220 m(2) g(-1), and the related carbon dioxide storage capacity was found to be 14...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694866/strategies-in-megasynthase-engineering-fatty-acid-synthases-fas-as-model-proteins
#5
REVIEW
Manuel Fischer, Martin Grininger
Megasynthases are large multienzyme proteins that produce a plethora of important natural compounds by catalyzing the successive condensation and modification of precursor units. Within the class of megasynthases, polyketide synthases (PKS) are responsible for the production of a large spectrum of bioactive polyketides (PK), which have frequently found their way into therapeutic applications. Rational engineering approaches have been performed during the last 25 years that seek to employ the "assembly-line synthetic concept" of megasynthases in order to deliver new bioactive compounds...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694865/towards-open-ended-evolution-in-self-replicating-molecular-systems
#6
REVIEW
Herman Duim, Sijbren Otto
In this review we discuss systems of self-replicating molecules in the context of the origin of life and the synthesis of de novo life. One of the important aspects of life is the ability to reproduce and evolve continuously. In this review we consider some of the prerequisites for obtaining unbounded evolution of self-replicating molecules and describe some recent advances in this field. While evolution experiments involving self-replicating molecules have shown promising results, true open-ended evolution has not been realized so far...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694864/phosphorus-pentasulfide-mediated-conversion-of-organic-thiocyanates-to-thiols
#7
Chandra Kant Maurya, Avik Mazumder, Pradeep Kumar Gupta
In this paper we report an efficient and mild procedure for the conversion of organic thiocyanates to thiols in the presence of phosphorus pentasulfide (P2S5) in refluxing toluene. The method avoids the use of expensive and hazardous transition metals and harsh reducing agents, as required by reported methods, and provides an attractive alternative to the existing methods for the conversion of organic thiocyanates to thiols.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28694863/kinetic-analysis-of-mechanoradical-formation-during-the-mechanolysis-of-dextran-and-glycogen
#8
Naoki Doi, Yasushi Sasai, Yukinori Yamauchi, Tetsuo Adachi, Masayuki Kuzuya, Shin-Ichi Kondo
A detailed electron spin resonance (ESR) analysis of mechanically induced free radicals (mechanoradicals) formation of glucose-based polysaccharides, dextran (Dx) and glycogen (Gly) was performed in comparison with amylose mechanoradicals. The ESR spectra of the samples mechanically fractured at room temperature were multicomponent. The radical concentration of Dx and Gly mechanoradicals gradually decreased during vibratory milling after reaching the maximum value. Although the molecular weight of Dx or the particle diameter of Gly steeply diminished until reaching the each maximum value of radical concentration, after that the molecular weight or the particle diameter slowly decreased...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684995/characterization-of-non-heme-iron-aliphatic-halogenase-welo5-fromhapalosiphon-welwitschiiic-52-3-identification-of-a-minimal-protein-sequence-motif-that-confers-enzymatic-chlorination-specificity-in-the-biosynthesis-of-welwitindolelinones
#9
Qin Zhu, Xinyu Liu
The in vitro biochemical characterization revealed that iron/2-oxoglutarate (Fe/2OG)-dependent aliphatic halogenase WelO5* in Hapalosiphon welwitschii IC-52-3 has an enhanced substrate specificity towards 12-epi-hapalindole C (1) in comparison to WelO5 in H. welwitschii UTEX B1830. This allowed us to define the origin of the varied chlorinated versus dechlorinated alkaloid structural diversity between the two welwitindolinone producers. Furthermore, this study, along with the recent characterization of the AmbO5 protein, collectively confirmed the presence of a signature sequence motif in the C-terminus of this newly discovered halogenase enzyme family that confers substrate promiscuity and specificity...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684994/glycoscience-synchrotron-synchrotron-radiation-applied-to-structural-glycoscience
#10
REVIEW
Serge Pérez, Daniele de Sanctis
Synchrotron radiation is the most versatile way to explore biological materials in different states: monocrystalline, polycrystalline, solution, colloids and multiscale architectures. Steady improvements in instrumentation have made synchrotrons the most flexible intense X-ray source. The wide range of applications of synchrotron radiation is commensurate with the structural diversity and complexity of the molecules and macromolecules that form the collection of substrates investigated by glycoscience. The present review illustrates how synchrotron-based experiments have contributed to our understanding in the field of structural glycobiology...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684993/urea-hydrogen-peroxide-prompted-the-selective-and-controlled-oxidation-of-thioglycosides-into-sulfoxides-and-sulfones
#11
Adesh Kumar Singh, Varsha Tiwari, Kunj Bihari Mishra, Surabhi Gupta, Jeyakumar Kandasamy
A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea-hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684992/correction-fluorescent-carbon-dots-from-mono-and-polysaccharides-synthesis-properties-and-applications
#12
Stephen Hill, M Carmen Galan
[This corrects the article DOI: 10.3762/bjoc.13.67.].
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684991/from-chemical-metabolism-to-life-the-origin-of-the-genetic-coding-process
#13
REVIEW
Antoine Danchin
Looking for origins is so much rooted in ideology that most studies reflect opinions that fail to explore the first realistic scenarios. To be sure, trying to understand the origins of life should be based on what we know of current chemistry in the solar system and beyond. There, amino acids and very small compounds such as carbon dioxide, dihydrogen or dinitrogen and their immediate derivatives are ubiquitous. Surface-based chemical metabolism using these basic chemicals is the most likely beginning in which amino acids, coenzymes and phosphate-based small carbon molecules were built up...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684990/an-eco-compatible-strategy-for-the-diversity-oriented-synthesis-of-macrocycles-exploiting-carbohydrate-derived-building-blocks
#14
Sushil K Maurya, Rohit Rana
An efficient, eco-compatible diversity-oriented synthesis (DOS) approach for the generation of library of sugar embedded macrocyclic compounds with various ring size containing 1,2,3-triazole has been developed. This concise strategy involves the iterative use of readily available sugar-derived alkyne/azide-alkene building blocks coupled through copper catalyzed azide-alkyne cycloaddition (CuAAC) reaction followed by pairing of the linear cyclo-adduct using greener reaction conditions. The eco-compatibility, mild reaction conditions, greener solvents, easy purification and avoidance of hazards and toxic solvents are advantages of this protocol to access this important structural class...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684989/correlation-of-surface-pressure-and-hue-of-planarizable-push-pull-chromophores-at-the-air-water-interface
#15
Frederik Neuhaus, Fabio Zobi, Gerald Brezesinski, Marta Dal Molin, Stefan Matile, Andreas Zumbuehl
It is currently not possible to directly measure the lateral pressure of a biomembrane. Mechanoresponsive fluorescent probes are an elegant solution to this problem but it requires first the establishment of a direct correlation between the membrane surface pressure and the induced color change of the probe. Here, we analyze planarizable dithienothiophene push-pull probes in a monolayer at the air/water interface using fluorescence microscopy, grazing-incidence angle X-ray diffraction, and infrared reflection-absorption spectroscopy...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684988/total-syntheses-of-the-archazolids-an-emerging-class-of-novel-anticancer-drugs
#16
REVIEW
Stephan Scheeff, Dirk Menche
V-ATPase has recently emerged as a promising novel anticancer target based on extensive in vitro and in vivo studies with the archazolids, complex polyketide macrolides which present the most potent V-ATPase inhibitors known to date, rendering these macrolides important lead structures for the development of novel anticancer agents. The limited natural supply of these metabolites from their myxobacterial source renders total synthesis of vital importance for the further preclinical development. This review describes in detail the various tactics and strategies employed so far in archazolid syntheses that culminated in three total syntheses and discusses the future synthetic challenges that have to be addressed...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684987/%C3%AE-acetoxyarone-synthesis-via-iodine-catalyzed-and-tert-butyl-hydroperoxide-mediateded-self-intermolecular-oxidative-coupling-of-aryl-ketones
#17
Liquan Tan, Cui Chen, Weibing Liu
We present a metal-free method for α-acetoxyarone synthesis by self-intermolecular oxidative coupling of aryl ketones using I2-tert-butyl hydroperoxide (TBHP). Under the optimum conditions, various aryl ketones gave the corresponding products in moderate to excellent yields. A series of control experiments were performed; the results suggest the involvement of radical pathways. Multiple radical intermediates were generated in situ and the overall process involved several different reactions, which proceeded self-sequentially in a single reactor...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684986/g-protein-coupled-receptors-answers-from-simulations
#18
REVIEW
Timothy Clark
Molecular-dynamics (MD) simulations are playing an increasingly important role in research into the modes of action of G-protein coupled receptors (GPCRs). In this field, MD simulations are unusually important as, because of the difficult experimental situation, they often offer the only opportunity to determine structural and mechanistic features in atomistic detail. Modern combinations of soft- and hardware have made MD simulations a powerful tool in GPCR research. This is important because GPCRs are targeted by approximately half of the drugs on the market, so that computer-aided drug design plays a major role in GPCR research...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684985/a-concise-and-practical-stereoselective-synthesis-of-ipragliflozin-l-proline
#19
Shuai Ma, Zhenren Liu, Jing Pan, Shunli Zhang, Weicheng Zhou
A concise and practical stereoselective synthesis of ipragliflozin L-proline was presented starting from 2-[(5-iodo-2-fluorophenyl)methyl]-1-benzothiophene and 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide without catalyst via iodine-lithium-zinc exchange. The overall yield was 52% in three steps and the product purity was excellent. Two key diastereomers were prepared with efficient and direct access to the α-C-arylglucoside.
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28684984/new-tricks-of-well-known-aminoazoles-in-isocyanide-based-multicomponent-reactions-and-antibacterial-activity-of-the-compounds-synthesized
#20
Maryna V Murlykina, Maryna N Kornet, Sergey M Desenko, Svetlana V Shishkina, Oleg V Shishkin, Aleksander A Brazhko, Vladimir I Musatov, Erik V Van der Eycken, Valentin A Chebanov
The well-known aminoazoles, 3-amino-5-methylisoxazole and 5-amino-N-aryl-1H-pyrazole-4-carboxamides, were studied as an amine component in Ugi and Groebke-Blackburn-Bienaymé multicomponent reactions. The first example of an application of aminoazoles in an Ugi four-component reaction was discovered and novel features of a Groebke-Blackburn-Bienaymé cyclocondensation are established and discussed. The heterocycles obtained were evaluated for their antibacterial activity and several of them demonstrated a weak antimicrobial effect, but for most of the compounds a 30-50% increase in biomass of Gram-positive strains (mainly B...
2017: Beilstein Journal of Organic Chemistry
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