2,676 results match your criteria Beilstein Journal of Organic Chemistry [Journal]


Synthesis of nonracemic hydroxyglutamic acids.

Beilstein J Org Chem 2019 25;15:236-255. Epub 2019 Jan 25.

Bioorganic Chemistry Laboratory, Faculty of Pharmacy, Medical University of Lodz, Muszynskiego 1, 90-151 Lodz, Poland.

Glutamic acid is involved in several cellular processes though its role as the neurotransmitter is best recognized. For detailed studies of interactions with receptors a number of structural analogues of glutamic acid are required to map their active sides. This review article summarizes syntheses of nonracemic hydroxyglutamic acid analogues equipped with functional groups capable for the formation of additional hydrogen bonds, both as donors and acceptors. Read More

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http://dx.doi.org/10.3762/bjoc.15.22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350885PMC
January 2019

Olefin metathesis in multiblock copolymer synthesis.

Beilstein J Org Chem 2019 24;15:218-235. Epub 2019 Jan 24.

Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninsky prosp. 29, 119991 Moscow, Russia.

Multiblock copolymers constitute a basis for an emerging class of nanomaterials that combine various functional properties with durability and enhanced mechanical characteristics. Our mini-review addresses synthetic approaches to the design of multiblock copolymers from unsaturated monomers and polymers using olefin metathesis reactions and other ways of chemical modification across double C=C bonds. The main techniques, actively developed during the last decade and discussed here, are the coupling of end-functionalized blocks, sequential ring-opening metathesis polymerization, and cross metathesis between unsaturated polymers, or macromolecular cross metathesis. Read More

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http://dx.doi.org/10.3762/bjoc.15.21DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350893PMC
January 2019

First synthesis of cryptands with sucrose scaffold.

Beilstein J Org Chem 2019 23;15:210-217. Epub 2019 Jan 23.

Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.

Cryptands with sucrose scaffold, an unknown class of such derivatives, were prepared from the readily available 2,3,3',4,4'-penta--benzylsucrose and 1',2,3,3',4,4'-hexa--benzylsucrose. Read More

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http://dx.doi.org/10.3762/bjoc.15.20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350891PMC
January 2019

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands.

Beilstein J Org Chem 2019 22;15:194-209. Epub 2019 Jan 22.

Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Hoffmann Street, 2531 Potchefstroom, South Africa.

Four new Grubbs-type precatalysts [RuCl(HIMes)(O^N)(=CHPh)], where [O^N = α,α-diphenyl-(3-methylpyridin-2-yl)methanolato, α,α-diphenyl-(4-methylpyridin-2-yl)methanolato, α,α-diphenyl-(5-methylpyridin-2-yl)methanolato and α,α-diphenyl-(3-methoxypyridin-2-yl)methanolato] were synthesized and tested for their activity, stability and selectivity in the 1-octene metathesis reaction. Overall the precatalysts showed good activity and high stability for the metathesis of 1-octene at temperatures above 80 °C and up to 110 °C. Selectivities towards the primary metathesis products, i. Read More

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https://www.beilstein-journals.org/bjoc/articles/15/19
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http://dx.doi.org/10.3762/bjoc.15.19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350883PMC
January 2019
1 Read

Synthesis and biological activity of methylated derivatives of the metabolites HHQ, HQNO and PQS.

Beilstein J Org Chem 2019 21;15:187-193. Epub 2019 Jan 21.

Organic Chemistry Institute, University of Münster, Corrensstr. 40, 48149 Münster, Germany.

Selectively methylated analogues of naturally occurring 2-heptyl-4(1)-quinolones, which are alkaloids common within the Rutaceae family and moreover are associated with quorum sensing and virulence of the human pathogen , have been prepared. While the synthesis by direct methylation was successful for 3-unsubstituted 2-heptyl-4(1)-quinolones, methylated derivatives of the quinolone signal (PQS) were synthesized from 3-iodinated quinolones by methylation and iodine-metal exchange/oxidation. The two - and -methylated derivatives of the PQS showed strong quorum sensing activity comparable to that of PQS itself. Read More

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http://dx.doi.org/10.3762/bjoc.15.18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350858PMC
January 2019
1 Read

Silanediol versus chlorosilanol: hydrolyses and hydrogen-bonding catalyses with fenchole-based silanes.

Beilstein J Org Chem 2019 18;15:167-186. Epub 2019 Jan 18.

Department für Chemie, Institut für Organische Chemie, Greinstrasse 4, 50939 Köln, Germany.

Biphenyl-2,2'-bisfenchyloxydichlorosilane (, BIFOXSiCl) is synthesized and employed as precursor for the new silanols biphenyl-2,2'-bisfenchyloxychlorosilanol (, BIFOXSiCl(OH)) and biphenyl-2,2'-bisfenchyloxysilanediol (, BIFOXSi(OH)). BIFOXSiCl () shows a remarkable stability against hydrolysis, yielding silanediol under enforced conditions. A kinetic study for the hydrolysis of dichlorosilane shows a 263 times slower reaction compared to reference bis-(2,4,6-tri--butylphenoxy)dichlorosilane (), known for its low hydrolytic reactivity. Read More

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http://dx.doi.org/10.3762/bjoc.15.17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350884PMC
January 2019

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation.

Beilstein J Org Chem 2019 17;15:160-166. Epub 2019 Jan 17.

Wrocław University of Science and Technology, Faculty of Chemistry, Wybrzeże Wyspiańskiego 29, 50-370 Wrocław, Poland.

The influence of microwave and ultrasonic irradiation on the performance of ammonium-tagged Ru-based catalysts in olefin metathesis transformations in aqueous media was studied. Differences in the catalytic activity in correlation with the nature of the present counter ion and the size of the -heterocyclic carbene (NHC) ligand were revealed. The presented methodology allows for preparation of a variety of polar and non-polar metathesis products under environmentally friendly conditions. Read More

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http://dx.doi.org/10.3762/bjoc.15.16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350890PMC
January 2019

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis.

Beilstein J Org Chem 2019 16;15:145-159. Epub 2019 Jan 16.

Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.

Thiamin diphosphate (ThDP)-dependent enzymes constitute a large class of enzymes that catalyze a diverse range of reactions. Many are involved in stereospecific carbon-carbon bond formation and, consequently, have found increasing interest and utility as chiral catalysts in various biocatalytic applications. All ThDP-catalyzed reactions require the reaction of the ThDP ylide (the activated state of the cofactor) with the substrate. Read More

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http://dx.doi.org/10.3762/bjoc.15.15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350894PMC
January 2019

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides.

Beilstein J Org Chem 2019 15;15:137-144. Epub 2019 Jan 15.

Glycosystems Laboratory, Instituto de Investigaciones Químicas (IIQ), cicCartuja, CSIC and Universidad de Sevilla, Americo Vespucio, 49, 41092 Sevilla, Spain.

Here, we present an exploratory study on the fluorous-assisted synthesis of chondroitin sulfate (CS) oligosaccharides. Following this approach, a CS tetrasaccharide was prepared. However, in contrast to our previous results, a significant loss of β-selectivity was observed in [2 + 2] glycosylations involving -trifluoroacetyl-protected D-galactosamine donors and D-glucuronic acid (GlcA) acceptors. Read More

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http://dx.doi.org/10.3762/bjoc.15.14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350880PMC
January 2019

Systematic synthetic study of four diastereomerically distinct limonene-1,2-diols and their corresponding cyclic carbonates.

Beilstein J Org Chem 2019 14;15:130-136. Epub 2019 Jan 14.

Graduate School of Engineering, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki-city 852-8521, Japan.

In order to produce versatile and potentially functional terpene-based compounds, a ()-limonene-derived diol and its corresponding five-membered cyclic carbonate were prepared. The diol (cyclic carbonate) comprises four diastereomers based on the stereochemical configuration of the diol (and cyclic carbonate) moiety. By choosing the appropriate starting compounds (- and -limonene oxide) and conditions, the desired diastereomers were synthesised in moderate to high yields with, in most cases, high stereoselectivity. Read More

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http://dx.doi.org/10.3762/bjoc.15.13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350878PMC
January 2019

Adhesion, forces and the stability of interfaces.

Beilstein J Org Chem 2019 11;15:106-129. Epub 2019 Jan 11.

Department of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria.

Weak molecular interactions (WMI) are responsible for processes such as physisorption; they are essential for the structure and stability of interfaces, and for bulk properties of liquids and molecular crystals. The dispersion interaction is one of the four basic interactions types - electrostatics, induction, dispersion and exchange repulsion - of which all WMIs are composed. The fact that each class of basic interactions covers a wide range explains the large variety of WMIs. Read More

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http://dx.doi.org/10.3762/bjoc.15.12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334800PMC
January 2019

Synthesis of a tubugi-1-toxin conjugate by a modulizable disulfide linker system with a neuropeptide Y analogue showing selectivity for hY1R-overexpressing tumor cells.

Beilstein J Org Chem 2019 10;15:96-105. Epub 2019 Jan 10.

Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany.

Tubugi-1 is a small cytotoxic peptide with picomolar cytotoxicity. To improve its cancer cell targeting, it was conjugated using a universal, modular disulfide derivative. This allowed conjugation to a neuropeptide-Y (NPY)-inspired peptide [K(C-βA-),F,L,P]-hNPY, acting as NPY Y1 receptor (hY1R)-targeting peptide, to form a tubugi-1-SS-NPY disulfide-linked conjugate. Read More

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http://dx.doi.org/10.3762/bjoc.15.11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334802PMC
January 2019

Fabrication of supramolecular cyclodextrin-fullerene nonwovens by electrospinning.

Beilstein J Org Chem 2019 9;15:89-95. Epub 2019 Jan 9.

Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.

Direct electrospinning of small molecules has great potential to fabricate a new class of fiber materials because this approach realizes the creation of various functional materials through the numerous molecular combinations. In this paper, we demonstrate a proof-of-concept to fabricate supramolecular fiber materials composed of cyclodextrin (CD)-fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. Read More

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http://dx.doi.org/10.3762/bjoc.15.10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334797PMC
January 2019

Synthesis, biophysical properties, and RNase H activity of 6'-difluoro[4.3.0]bicyclo-DNA.

Beilstein J Org Chem 2019 8;15:79-88. Epub 2019 Jan 8.

Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.

Here we present the synthesis, the biophysical properties, and the RNase H profile of 6'-difluorinated [4.3.0]bicyclo-DNA (6'-diF-bc-DNA). Read More

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http://dx.doi.org/10.3762/bjoc.15.9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334804PMC
January 2019

Regioselective addition of Grignard reagents to -acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ-2-oxopiperazines.

Beilstein J Org Chem 2019 8;15:72-78. Epub 2019 Jan 8.

Biomanufacturing Research Institute and Technology Enterprise (BRITE), North Carolina Central University, Durham, North Carolina 27707, United States.

The regioselective addition of Grignard reagents to mono- and disubstituted -acylpyrazinium salts affording substituted 1,2-dihydropyrazines in modest to excellent yields (45-100%) is described. Under acidic conditions, these 1,2-dihydropyrazines can be converted to substituted Δ-2-oxopiperazines providing a simple and efficient approach towards their preparation. Read More

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http://dx.doi.org/10.3762/bjoc.15.8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334805PMC
January 2019

Gold-catalyzed ethylene cyclopropanation.

Beilstein J Org Chem 2019 7;15:67-71. Epub 2019 Jan 7.

Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química, Universidad de Huelva, Campus de El Carmen 21007 Huelva, Spain.

Ethylene can be directly converted into ethyl 1-cyclopropylcarboxylate upon reaction with ethyl diazoacetate (NCHCOEt, EDA) in the presence of catalytic amounts of IPrAuCl/NaBAr (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene; BAr = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate). Read More

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http://dx.doi.org/10.3762/bjoc.15.7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334794PMC
January 2019

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases.

Beilstein J Org Chem 2019 7;15:60-66. Epub 2019 Jan 7.

Studio di Consulenza Scientifica (SCSOP), Via Bornò 5, 23896 Sirtori (LC), Italy.

Chiral N-heterocyclic molecules and in particular compounds with an amino functional group such as 3-aminopiperidine are valuable intermediates for the production of a large number of bioactive compounds with pharmacological properties. In this paper, the synthesis of both enantiomers of 3-amino-1-Boc-piperidine by amination of the prochiral precursor 1-Boc-3-piperidone using immobilized ω-transaminases (TAs-IMB), isopropylamine as amine donor and pyridoxal-5'-phosphate (PLP) as cofactor is described. Compared to other methods, the present approach affords the target compound in just one step with high yield and high enantiomeric excess starting from a commercial substrate. Read More

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http://dx.doi.org/10.3762/bjoc.15.6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334810PMC
January 2019

-Arylphenothiazines as strong donors for photoredox catalysis - pushing the frontiers of nucleophilic addition of alcohols to alkenes.

Beilstein J Org Chem 2019 4;15:52-59. Epub 2019 Jan 4.

Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.

A new range of -phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These -phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated -phenylphenothiazines were identified to be highly suitable for photoredox catalysis. Read More

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http://dx.doi.org/10.3762/bjoc.15.5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334793PMC
January 2019

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands.

Beilstein J Org Chem 2019 3;15:44-51. Epub 2019 Jan 3.

Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.

At 0 °C in THF in the presence of Grubbs first generation catalyst, cyclobutene derivatives undergo ROMP readily, whereas norbornene derivatives remain intact. When the substrate contains both cyclobutene and norbornene moieties, the conditions using THF as the solvent at 0 °C offer a useful protocol for the selective ROMP of cyclobutene to give norbornene-appended polycyclobutene. Unsymmetrical ladderphane having polycyclobutene and polynorbornene as two strands is obtained by further ROMP of the norbornene appended polycyclobutene in the presence of Grubbs first generation catalyst in DCM at ambient temperature. Read More

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http://dx.doi.org/10.3762/bjoc.15.4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334803PMC
January 2019

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels-Alder reaction with inverse electron demand.

Beilstein J Org Chem 2019 3;15:30-43. Epub 2019 Jan 3.

University of Bonn, Kekulé-Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany.

The mechanism of an L-proline-catalyzed pyridazine formation from acetone and aryl-substituted tetrazines via a Diels-Alder reaction with inverse electron demand has been studied with NMR and with electrospray ionization mass spectrometry. A catalytic cycle with three intermediates has been proposed. An enamine derived from L-proline and acetone acts as an electron-rich dienophile in a [4 + 2] cycloaddition with the electron-poor tetrazine forming a tetraazabicyclo[2. Read More

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http://dx.doi.org/10.3762/bjoc.15.3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334817PMC
January 2019

New standards for collecting and fitting steady state kinetic data.

Beilstein J Org Chem 2019 2;15:16-29. Epub 2019 Jan 2.

Department of Molecular Biosciences, The University of Texas, Austin, TX 78735, USA.

The Michaelis-Menten equation is usually expressed in terms of and values: = [S]/( + [S]). However, it is impossible to interpret in the absence of additional information, while the ratio of / provides a measure of enzyme specificity and is proportional to enzyme efficiency and proficiency. Moreover, / provides a lower limit on the second order rate constant for substrate binding. Read More

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http://dx.doi.org/10.3762/bjoc.15.2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334795PMC
January 2019

Lectins of - rarely studied proteins.

Beilstein J Org Chem 2019 2;15:1-15. Epub 2019 Jan 2.

Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3-4, 24118 Kiel, Germany.

The importance of bacterial lectins for adhesion, pathogenicity, and biofilm formation is well established for many Gram-positive and Gram-negative bacteria. However, there is very little information available about lectins of the tuberculosis-causing bacterium, (). In this paper we review previous studies on the carbohydrate-binding characteristics of mycobacteria and related proteins, discussing their potential relevance to infection and pathogenesis. Read More

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http://dx.doi.org/10.3762/bjoc.15.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334816PMC
January 2019
2 Reads

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands.

Beilstein J Org Chem 2018 28;14:3122-3149. Epub 2018 Dec 28.

Dipartimento di Chimica e Biologia "Adolfo Zambelli", Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Salerno, Italy.

An overview on the catalytic properties of ruthenium complexes for olefin metathesis bearing monodentate unsymmetrical N-heterocyclic diaminocarbene ligands is provided. The non-symmetric nature of these NHC architectures strongly influences activity and selectivity of the resulting catalysts. The main achievements that have been accomplished in significant areas of olefin metathesis up to the current state of research are discussed. Read More

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http://dx.doi.org/10.3762/bjoc.14.292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317415PMC
December 2018
1 Read

A simple and effective preparation of quercetin pentamethyl ether from quercetin.

Beilstein J Org Chem 2018 28;14:3112-3121. Epub 2018 Dec 28.

Tokiwa Phytochemical Co. Ltd., 158 Kinoko, Sakura, Chiba 285-0801, Japan.

Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per--methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. Read More

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http://dx.doi.org/10.3762/bjoc.14.291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317434PMC
December 2018
1 Read

A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety.

Beilstein J Org Chem 2018 27;14:3106-3111. Epub 2018 Dec 27.

P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninskiy prospect, 53, 119991 Moscow, Russian Federation.

A versatile and robust synthetic protocol for the preparation of β-diketones bearing 2-thienyl and perfluorinated alkyl radicals of different length or a methyl group was developed. This protocol is suitable for the preparation of multigram quantities of diketones without cumbersome purification procedures. Moreover, the known method for purification of diketones via copper chelates was improved considerably. Read More

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http://dx.doi.org/10.3762/bjoc.14.290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317410PMC
December 2018
1 Read

Thermophilic phosphoribosyltransferases HB27 in nucleotide synthesis.

Beilstein J Org Chem 2018 21;14:3098-3105. Epub 2018 Dec 21.

Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya Str., 16/10, Moscow, GSP-7, 117997, Russia.

Phosphoribosyltransferases are the tools that allow the synthesis of nucleotide analogues using multi-enzymatic cascades. The recombinant adenine phosphoribosyltransferase (APRT) and hypoxanthine phosphoribosyltransferase (HPRT) from HB27 were expressed in strains and purified by chromatographic methods with yields of 10-13 mg per liter of culture. The activity dependence of APRT and HPRT on different factors was investigated along with the substrate specificity towards different heterocyclic bases. Read More

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http://dx.doi.org/10.3762/bjoc.14.289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317416PMC
December 2018
2 Reads

6'-Fluoro[4.3.0]bicyclo nucleic acid: synthesis, biophysical properties and molecular dynamics simulations.

Beilstein J Org Chem 2018 20;14:3088-3097. Epub 2018 Dec 20.

Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.

Here we report on the synthesis, biophysical properties and molecular modeling of oligonucleotides containing unsaturated 6'-fluoro[4.3.0]bicyclo nucleotides (6'F-bc-DNA). Read More

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http://dx.doi.org/10.3762/bjoc.14.288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317435PMC
December 2018
2 Reads

Mn-mediated sequential three-component domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction towards annulated imidazo[1,2-]pyridines.

Beilstein J Org Chem 2018 19;14:3078-3087. Epub 2018 Dec 19.

Organic Chemistry Department, Peoples' Friendship University of Russia (RUDN University), Miklukho-Maklaya st. 6, 117198 Moscow, Russian Federation.

The sequential three-component reaction between -hydroxybenzaldehydes, -(cyanomethyl)pyridinium salts and a nucleophile towards substituted chromenoimidazopyridines under oxidative conditions has been developed. The employment of Mn(OAc)·2HO or KMnO as stoichiometric oxidants allowed the use of a wide range of nucleophiles, such as nitromethane, (aza)indoles, pyrroles, phenols, pyrazole, indazole and diethyl malonate. The formation of the target compounds presumably proceeds through a domino Knoevenagel/cyclization/Michael addition/oxidative cyclization reaction sequence. Read More

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http://dx.doi.org/10.3762/bjoc.14.287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317425PMC
December 2018
2 Reads

Dispersion interactions.

Beilstein J Org Chem 2018 18;14:3076-3077. Epub 2018 Dec 18.

Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.

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http://dx.doi.org/10.3762/bjoc.14.286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317409PMC
December 2018
1 Read

Cross metathesis-mediated synthesis of hydroxamic acid derivatives.

Beilstein J Org Chem 2018 17;14:3070-3075. Epub 2018 Dec 17.

Department of Chemistry, University of Kalyani, Kalyani - 741235, West Bengal, India.

An alternative synthesis of α,ß-unsaturated hydroxamates via cross metathesis between a class-I olefin and -benzyloxyacrylamide is reported. The reaction proceeds better in the presence of Grubbs' second generation catalyst within short time and in good yields (57-85%) with a range of substrates. Subsequent hydrogenation of each of the CM products delivers the title compounds in moderate to very good yield (70-89%). Read More

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http://dx.doi.org/10.3762/bjoc.14.285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317413PMC
December 2018
2 Reads

Repurposing the anticancer drug cisplatin with the aim of developing novel infection control agents.

Beilstein J Org Chem 2018 14;14:3059-3069. Epub 2018 Dec 14.

Singapore Centre for Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore 637551.

Antibiotic resistance threatens effective treatment of microbial infections globally. This situation has spurred the hunt for new antimicrobial compounds in both academia and the pharmaceutical industry. Here, we report how the widely used antitumor drug cisplatin may be repurposed as an effective antimicrobial against the nosocomial pathogen . Read More

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https://www.beilstein-journals.org/bjoc/articles/14/284
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http://dx.doi.org/10.3762/bjoc.14.284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296412PMC
December 2018
8 Reads
2.762 Impact Factor

Degenerative xanthate transfer to olefins under visible-light photocatalysis.

Beilstein J Org Chem 2018 13;14:3047-3058. Epub 2018 Dec 13.

Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.

The degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [Ir{dF(CF)ppy}(dtbbpy)](PF) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and photophysical studies revealed that the process operates under a radical chain mechanism, which is initiated through triplet-sensitization of xanthates by the long-lived triplet state of the iridium-based photocatalyst. Read More

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http://dx.doi.org/10.3762/bjoc.14.283DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296426PMC
December 2018
1 Read

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region.

Beilstein J Org Chem 2018 12;14:3025-3046. Epub 2018 Dec 12.

Aix Marseille Univ, CNRS, ICR UMR 7273, F-13397 Marseille, France.

Recent progresses achieved in terms of synthetic procedures allow now the access to polymers of well-defined composition, molecular weight and architecture. Thanks to these recent progresses in polymer engineering, the scope of applications of polymers is far wider than that of any other class of material, ranging from adhesives, coatings, packaging materials, inks, paints, optics, 3D printing, microelectronics or textiles. From a synthetic viewpoint, photoredox catalysis, originally developed for organic chemistry, has recently been applied to the polymer synthesis, constituting a major breakthrough in polymer chemistry. Read More

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http://dx.doi.org/10.3762/bjoc.14.282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296434PMC
December 2018
1 Read

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion.

Beilstein J Org Chem 2018 11;14:3018-3024. Epub 2018 Dec 11.

Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377 München, Germany.

Sterically well-shielded against unsolicited Michael addition and polymerization reactions, α-metalated α-(1,1,3,3-tetramethylindan-2-ylidene)acetonitriles added reversibly to three small aldehydes and two bulky ketones at room temperature. Experimental conditions were determined for transfer of the nucleofugal title carbanion unit between different carbonyl compounds. These readily occurring retro-additions via C-C(O) bond fission may also be used to generate different metal derivatives of the nucleofugal anions as equilibrium components. Read More

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http://dx.doi.org/10.3762/bjoc.14.281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296431PMC
December 2018
2 Reads

Reactions of 3-(-substituted-phenyl)-5-chloromethyl-1,2,4-oxadiazoles with KCN leading to acetonitriles and alkanes via a non-reductive decyanation pathway.

Beilstein J Org Chem 2018 10;14:3011-3017. Epub 2018 Dec 10.

Department of Chemistry, Faculty of Arts & Sciences, Bolu Abant Izzet Baysal University, Bolu, TR14030, Turkey.

The present work describes an unfamiliar reaction of 5-(chloromethyl)-3-substituted-phenyl-1,2,4-oxadiazoles with KCN affording trisubstituted 1,2,4-oxadiazol-5-ylacetonitriles and their parent alkanes, namely, 1,2,3-trisubstituted-1,2,4-oxadiazol-5-ylpropanes. To the best of our knowledge, the current synthetic route leading to decyanated products will be the first in terms of a decyanation process which allows the transformation of trisubstituted acetonitriles into alkanes by the incorporation of KCN with the association of in situ-formed HCN and most likely through the extrusion of cyanogen which could not be detected or isolated. In addition, the plausible mechanisms were proposed for both transformations. Read More

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http://dx.doi.org/10.3762/bjoc.14.280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296410PMC
December 2018
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A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts.

Beilstein J Org Chem 2018 7;14:2999-3010. Epub 2018 Dec 7.

Univ. Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France.

Stereoretentive olefin metathesis based on ruthenium dithiolate complexes has become a very active field of research within the past years. This unique catalyst class is able to kinetically produce both - and -alkenes in high stereochemical purity (typically >95:5) starting from stereochemically pure - or -alkenes. The aim of this tutorial review is to organize the reported information concerning ruthenium dithiolate catalysts in a logic manner, thus providing an "operators handbook" for chemists who wish to apply this methodology in synthesis. Read More

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http://dx.doi.org/10.3762/bjoc.14.279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296435PMC
December 2018
2 Reads

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins.

Beilstein J Org Chem 2018 5;14:2991-2998. Epub 2018 Dec 5.

Universität Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24-25, D-14476 Potsdam-Golm, Germany.

8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination/cyclization sequence. They serve as a versatile platform for the annellation of five- to seven-membered rings using ring-closing olefin metathesis (RCM). Furano-, pyrano-, oxepino- and azepinocoumarins were synthesized from the same set of precursors using Ru-catalyzed double bond isomerizations and RCM in a defined order. Read More

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http://dx.doi.org/10.3762/bjoc.14.278DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296409PMC
December 2018
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Volatiles from the hypoxylaceous fungi and .

Beilstein J Org Chem 2018 4;14:2974-2990. Epub 2018 Dec 4.

Kekulé-Institut für Organische Chemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany.

The volatiles emitted by the ascomycetes and (Hypoxylaceae, Xylariales) were collected by use of a closed-loop stripping apparatus (CLSA) and analysed by GC-MS. The main compound class of both species were polysubstituted benzene derivatives. Their structures could only be unambiguously determined by comparison to all isomers with different substitution patterns. Read More

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http://dx.doi.org/10.3762/bjoc.14.277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296411PMC
December 2018
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2.762 Impact Factor

-Acylated amino acid methyl esters from marine group bacteria.

Beilstein J Org Chem 2018 3;14:2964-2973. Epub 2018 Dec 3.

Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.

Bacteria of the group (Rhodobacteraceae) are important members of many marine ecosystems. Similar to other Gram-negative bacteria many roseobacters produce -acylhomoserine lactones (AHLs) for communication by quorum sensing systems. AHLs regulate different traits like cell differentiation or antibiotic production. Read More

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https://www.beilstein-journals.org/bjoc/articles/14/276
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http://dx.doi.org/10.3762/bjoc.14.276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296433PMC
December 2018
4 Reads
2.762 Impact Factor

The activity of indenylidene derivatives in olefin metathesis catalysts.

Beilstein J Org Chem 2018 30;14:2956-2963. Epub 2018 Nov 30.

Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, c/ Mª Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.

The first turnover event of an olefin metathesis reaction using a new family of homogenous Ru-based catalysts bearing modified indenylidene ligands has been investigated, using methoxyethylene as a substrate. The study is carried out by means of density functional theory (DFT). The indenylidene ligands are decorated with -methyl and isopropyl groups at both positions of their phenyl ring. Read More

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http://dx.doi.org/10.3762/bjoc.14.275DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278753PMC
November 2018
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Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step.

Beilstein J Org Chem 2018 29;14:2949-2955. Epub 2018 Nov 29.

Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, 263 avenue du Général Leclerc, Campus de Beaulieu, F-35000 Rennes, France.

In this paper, a new access to several chiral 3-aminoglycals as potential precursors for glycosylated natural products is reported from a common starting material, (-)-methyl-L-lactate. The stereodivergent strategy is based on the implementation of a ring-closing metathesis of vinyl ethers as key step of reaction sequences developed. Read More

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http://dx.doi.org/10.3762/bjoc.14.274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278755PMC
November 2018
1 Read

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation.

Beilstein J Org Chem 2018 28;14:2940-2948. Epub 2018 Nov 28.

Institute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russian Federation.

The structure and protonation behaviour of four -arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It has been shown that -isomers of neutral imines can be stabilised by an intramolecular C=N-H···OMe hydrogen bond with a neighbouring methoxy group. Read More

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http://dx.doi.org/10.3762/bjoc.14.273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278759PMC
November 2018
2 Reads

MoO on zeolites MCM-22, MCM-56 and 2D-MFI as catalysts for 1-octene metathesis.

Beilstein J Org Chem 2018 27;14:2931-2939. Epub 2018 Nov 27.

J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.

Highly active olefin metathesis catalysts were prepared by thermal spreading MoO and/or MoO(acac) on MWW zeolites (MCM-22, delaminated MCM-56) and on two-dimensional MFI (all in NH form). The catalysts' activities were tested in the metathesis of neat 1-octene (as an example of a longer chain olefin) at 40 °C. Catalysts with 6 wt % or 5 wt % of Mo were used. Read More

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http://dx.doi.org/10.3762/bjoc.14.272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278768PMC
November 2018
4 Reads

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium.

Beilstein J Org Chem 2018 26;14:2923-2930. Epub 2018 Nov 26.

Laboratoire de Synthèse Organique Asymétrique et Catalyse Homogène, (UR 11ES56) Université de Monastir, Faculté des Sciences de Monastir, avenue de l'environnement, 5000 Monastir, Tunisie. ; Tel: (+216) 73.

New chiral 1-(arylamino)imidazo[2,1-]isoindole-2,5-dione derivatives were obtained in good to excellent yields via the cyclocondensation of 2-formylbenzoic acid and various α-amino acid arylhydrazides using water as the solvent in the presence of sodium dodecyl sulfate as the surfactant and under simple and minimum manipulation, without purification. The reaction is totally diastereoselective and gives access to the nitrogenated tricyclic core with a relative stereochemistry. Read More

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http://dx.doi.org/10.3762/bjoc.14.271DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278760PMC
November 2018
1 Read

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes.

Beilstein J Org Chem 2018 23;14:2916-2922. Epub 2018 Nov 23.

Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Center for Excellence in Molecular Synthesis, Chinese Academy of Sciences, 155 Yangqiao Road West, Fuzhou, Fujian 350002, P. R. China.

A copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction for the synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and terminal alkynes is reported. The alkyl carboxylic acids is for the first time being used as the alkyl azide precursors in the form of alkyl diacyl peroxides. This method avoids the necessity to handle organic azides, as they are generated in situ, making this protocol operationally simple. Read More

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http://dx.doi.org/10.3762/bjoc.14.270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278767PMC
November 2018
1 Read

Synthesis of indole-cycloalkyl[]pyridine hybrids via a four-component six-step tandem process.

Beilstein J Org Chem 2018 22;14:2907-2915. Epub 2018 Nov 22.

Department of Organic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India.

The one-pot four-component reaction of 3-(1-indol-3-yl)-3-oxopropanenitriles, aromatic aldehydes, cycloalkanones and ammonium acetate occurred via a six-step tandem Knoevenagel condensation-nucleophilic addition to carbonyl-Michael addition-N-cyclization-elimination-air oxidation sequence to afford structurally intriguing indole-cycloalkyl[]pyridine-3-carbonitrile hybrid heterocycles in excellent yields. Read More

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http://dx.doi.org/10.3762/bjoc.14.269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278771PMC
November 2018
3 Reads

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions.

Beilstein J Org Chem 2018 22;14:2897-2906. Epub 2018 Nov 22.

Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University, Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia.

In strong Brønsted acids (CFSOH, FSOH, DSO), (arysulfonyl)allenes (ArSO-CR=C=CRR) and (arylsulfinyl)allenes (ArSO-CR=C=CRR) undergo cyclization into the corresponding stable 1,2-oxathiolium ions, which were studied by means of NMR and DFT calculations. Quenching of solutions of these cations with low nucleophilic media, aqueous HCl, leads to their deprotonation with a stereoselective formation of (arysulfonyl)butadienes (for instance, ArSO-CR=C-C(Me)=CH, for R = R = Me, yields of 87-98%). Reactions of (arysulfonyl)allenes in the system TfOH (0. Read More

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http://dx.doi.org/10.3762/bjoc.14.268DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278758PMC
November 2018
1 Read

Protein-protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics.

Authors:
Laura Carro

Beilstein J Org Chem 2018 21;14:2881-2896. Epub 2018 Nov 21.

School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.

Antibiotics are potent pharmacological weapons against bacterial infections; however, the growing antibiotic resistance of microorganisms is compromising the efficacy of the currently available pharmacotherapies. Even though antimicrobial resistance is not a new problem, antibiotic development has failed to match the growth of resistant pathogens and hence, it is highly critical to discover new anti-infective drugs with novel mechanisms of action which will help reducing the burden of multidrug-resistant microorganisms. Protein-protein interactions (PPIs) are involved in a myriad of vital cellular processes and have become an attractive target to treat diseases. Read More

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http://dx.doi.org/10.3762/bjoc.14.267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278769PMC
November 2018
1 Read

The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study.

Beilstein J Org Chem 2018 20;14:2872-2880. Epub 2018 Nov 20.

Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warszawa, Poland.

Cationic carbenes are a relatively new and rare group of ancillary ligands, which have shown their superior activity in a number of challenging catalytic reactions. In ruthenium-based metathesis catalysis they are often used as ammonium tags, to provide water-soluble, environment-friendly catalysts. In this work we performed computational studies on three cationic carbenes with the formal positive charge located at different distances from the carbene carbon. Read More

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https://www.beilstein-journals.org/bjoc/articles/14/266
Publisher Site
http://dx.doi.org/10.3762/bjoc.14.266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278762PMC
November 2018
2 Reads

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis.

Beilstein J Org Chem 2018 19;14:2861-2871. Epub 2018 Nov 19.

Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

This review summarizes the recent progress of Grubbs-Hoveyda (GH) type olefin metathesis catalysts incorporated into the robust fold of β-barrel proteins. Anchoring strategies are discussed and challenges and opportunities in this emerging field are shown from simple small-molecule transformations over ring-opening metathesis polymerizations to in vivo olefin metathesis. Read More

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http://dx.doi.org/10.3762/bjoc.14.265DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6278764PMC
November 2018
1 Read