An Effective Approach to 1,2,3-Triazole-Containing 12-Vertex closo-Dodecaborates

2007 ◽  
Vol 72 (12) ◽  
pp. 1717-1724 ◽  
Author(s):  
Andrey A. Semioshkin ◽  
Sergey N. Osipov ◽  
Julia N. Grebenyuk ◽  
Evgueniya A. Nizhnik ◽  
Ivan A. Godovikov ◽  
...  
Keyword(s):  
Dipolar Cycloaddition ◽  
Synthetic Approach ◽  
Wide Range ◽  
Nucleophilic Cleavage

An efficient general synthetic approach giving a facile, rapid and inexpensive access to a wide range of novel 1,2,3-triazoles bearing closo-dodecaborate fragment has been developed. The method is based on the nucleophilic cleavage of oxonium dodecaborate with NaN3 or tertiary propargylamine and subsequent Huisgen 1,3-dipolar cycloaddition ("click" methodology) of the cleavage products and organic acetylenes or azides.

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

Historical Dynamics

2018 ◽  
Author(s):  
Peter Turchin
Keyword(s):  
Religious Conversion ◽  
Synthetic Approach ◽  
Dynamical Processes ◽  
Factors Affecting ◽  
Historical Processes ◽  
Wide Range ◽  
Historical Dynamics ◽  
State Breakdown ◽  
Political Economic ◽  
High Degree

Many historical processes are dynamic. Populations grow and decline. Empires expand and collapse. Religions spread and wither. Natural scientists have made great strides in understanding dynamical processes in the physical and biological worlds using a synthetic approach that combines mathematical modeling with statistical analyses. Taking up the problem of territorial dynamics—why some polities at certain times expand and at other times contract—this book shows that a similar research program can advance our understanding of dynamical processes in history. The book develops hypotheses from a wide range of social, political, economic, and demographic factors: geopolitics, factors affecting collective solidarity, dynamics of ethnic assimilation/religious conversion, and the interaction between population dynamics and sociopolitical stability. It then translates these into a spectrum of mathematical models, investigates the dynamics predicted by the models, and contrasts model predictions with empirical patterns. The book's highly instructive empirical tests demonstrate that certain models predict empirical patterns with a very high degree of accuracy. For instance, one model accounts for the recurrent waves of state breakdown in medieval and early modern Europe. And historical data confirm that ethno-nationalist solidarity produces an aggressively expansive state under certain conditions (such as in locations where imperial frontiers coincide with religious divides). The strength of the book's results suggests that the synthetic approach advocated can significantly improve our understanding of historical dynamics.

Unprecedented Copper(II) Coordination Induced Nucleophilic Cleavage of Quinoxaline Heterocycle: Structural and Computational Studies

CrystEngComm ◽  
2021 ◽  
Author(s):  
Bhaskar Biswas ◽  
Nilaj Banerjee ◽  
Mayank Joshi ◽  
Stevan Armaković ◽  
Sanja J Armaković ◽  
...  
Keyword(s):  
Synthetic Approach ◽  
Computational Studies ◽  
Quinoxaline Derivative ◽  
Catalyst Free ◽  
Nucleophilic Cleavage

A straightforward catalyst-free synthetic approach has been developed for the synthesis of quinoxaline derivative, 4-phenyl-4-(pyridin-2-yl)-4,5-dihydropyrrolo[1,2-a]quinoxaline (L) by the reaction of 2-benzoyl pyridine and pyrrole-1-anillin in ethanol. The L in presence...

scholarly journals The 3-O-sulfation of heparan sulfate modulates protein binding and lyase degradation

2021 ◽  
Vol 118 (3) ◽  
pp. e2012935118
Author(s):  
Pradeep Chopra ◽  
Apoorva Joshi ◽  
Jiandong Wu ◽  
Weigang Lu ◽  
Tejabhiram Yadavalli ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Binding Proteins ◽  
Factor Xa ◽  
Tissue Expression ◽  
Cell Entry ◽  
Synthetic Approach ◽  
Array Technology ◽  
Wide Range ◽  
Simplex Virus

Humans express seven heparan sulfate (HS) 3-O-sulfotransferases that differ in substrate specificity and tissue expression. Although genetic studies have indicated that 3-O-sulfated HS modulates many biological processes, ligand requirements for proteins engaging with HS modified by 3-O-sulfate (3-OS) have been difficult to determine. In particular, the context in which the 3-OS group needs to be presented for binding is largely unknown. We describe herein a modular synthetic approach that can provide structurally diverse HS oligosaccharides with and without 3-OS. The methodology was employed to prepare 27 hexasaccharides that were printed as a glycan microarray to examine ligand requirements of a wide range of HS-binding proteins. The binding selectivity of antithrombin-III (AT-III) compared well with anti-Factor Xa activity supporting robustness of the array technology. Many of the other examined HS-binding proteins required an IdoA2S-GlcNS3S6S sequon for binding but exhibited variable dependence for the 2-OS and 6-OS moieties, and a GlcA or IdoA2S residue neighboring the central GlcNS3S. The HS oligosaccharides were also examined as inhibitors of cell entry by herpes simplex virus type 1, which, surprisingly, showed a lack of dependence of 3-OS, indicating that, instead of glycoprotein D (gD), they competitively bind to gB and gC. The compounds were also used to examine substrate specificities of heparin lyases, which are enzymes used for depolymerization of HS/heparin for sequence determination and production of therapeutic heparins. It was found that cleavage by lyase II is influenced by 3-OS, while digestion by lyase I is only affected by 2-OS. Lyase III exhibited sensitivity to both 3-OS and 2-OS.

Combinatorial Synthesis of Exohedrally Modified Fullerene Derivatives

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1910-1915 ◽  
Author(s):  
Yasuhiko Kawamura ◽  
Yasuyuki Akai ◽  
Masao Tsukayama
Keyword(s):  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Combinatorial Synthesis ◽  
Environmentally Benign ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Compound Library ◽  
Phase Synthesis ◽  
Fullerene Derivatives ◽  
Wide Range

Fulleropyrrolidines have been very welcomed in a community of a fullerene science. But sometimes the synthesis ends up with disappointing yields of the products. In order to overcome the problem and to explore more environmentally benign method for synthesizing fullerene derivatives having various attachment on the surface of the fullerenes, a solid-phase synthesis is examined. We found that the dipolar cycloaddition of an azomethine ylide, i.e., 2-phenyl-N-benzylideneglycine methyl ester, supported on a Wang resin, proceeded feasibly with C 60 and the objective fulleropyrrolidines were afforded in good yields (>75%). The method is expected to be utilized with wide range of application and it is therefore able to provide a compound library of modified fullerenes which is hard to obtain by other methods employed so far.

Biobased Spiroimides from Itaconic Acid and Formamides: Molecular Targets for a Novel Synthetic Application of Renewable Chemicals

Synthesis ◽  
2020 ◽  
Vol 53 (02) ◽  
pp. 296-308
Author(s):  
Leandro Helgueira Andrade ◽  
Milene Macedo Hornink ◽  
Alice Uva Lopes
Keyword(s):  
Itaconic Acid ◽  
Biological Activities ◽  
Molecular Targets ◽  
Synthetic Approach ◽  
Renewable Chemicals ◽  
Wide Range ◽  
Synthetic Application

AbstractSpiroimides exhibit a wide range of biological activities, such as anticonvulsant, antiarrhythmic, and antihyperglycemic activities. Herein, a novel synthetic application of renewable chemicals, itaconic acid and formamides, is described. Proper exploitation of the reactivity of itaconic acid and formamide allows for the development of an efficient synthetic approach for the production of several new biobased spiroimides, spiro[dihydroquinolin-2-one-succinimides] and spiro[indolin-2-one-glutarimides], in excellent overall yields (up to 98%).

Preparation of enantiopure long chain threo-2-amino-3-hydroxyesters via chiral morpholinone-derived azomethine ylids

2006 ◽  
Vol 84 (10) ◽  
pp. 1448-1455 ◽  
Author(s):  
Victoria A Brome ◽  
Laurence M Harwood ◽  
Helen MI Osborn
Keyword(s):  
Amino Acid ◽  
Building Blocks ◽  
Dipolar Cycloaddition ◽  
Amino Acid Derivatives ◽  
Synthetic Approach ◽  
Alkyl Chains ◽  
Long Chain

The synthetic approach to threo-2-amino-3-hydroxyesters possessing long alkyl chains outlined herein centres on the generation of chiral azomethine ylids by reaction of (5R)-5-phenyl-morpholin-2-one, (R)-(1), with long chain aldehydes. In the presence of a second equivalent of aldehyde, the azomethine ylid can be trapped to afford a cycloadduct with three new stereodefined centres. Degradation of the cycloadduct allows entry to β-substituted-α-amino acid derivatives, which have potential as building blocks for sphingosine synthesis.Key words: sphingosine, morpholinone, chiral azomethine ylid, dipolar cycloaddition.

scholarly journals A synthetic approach reveals a highly sensitive maize auxin response circuit

2019 ◽  
Author(s):  
Román Ramos Báez ◽  
Yuli Buckley ◽  
Han Yu ◽  
Zongliang Chen ◽  
Andrea Gallavotti ◽  
...  
Keyword(s):  
Auxin Signaling ◽  
Synthetic Approach ◽  
Auxin Response ◽  
Auxin Receptor ◽  
Repressor Proteins ◽  
Highly Sensitive ◽  
Signaling Function ◽  
Wide Range ◽  
Signaling Components

Auxin plays a key role across all land plants in growth and developmental processes. Although auxin signaling function has diverged and expanded, differences in the molecular functions of signaling components have largely been characterized in Arabidopsis thaliana. Here, we used the Auxin Response Circuit recapitulated in Saccharomyces cerevisiae (ARCSc) system to functionally annotate maize auxin signaling components, focusing on genes expressed during development of ear and tassel inflorescences. All 16 maize Auxin (Aux)/Indole-3-Acetic Acid (IAA) repressor proteins are degraded in response to auxin, with rates that depended on both receptor and repressor identity. When fused to the maize TOPLESS (TPL) homolog RAMOSA1 ENHANCER LOCUS2 (REL2), maize Aux/IAAs were able to repress AUXIN RESPONSE FACTOR (ARF) transcriptional activity. A complete auxin response circuit comprised of all maize components, including ZmAFB2/3 b1 maize AUXIN SIGNALING F-BOX (AFB) receptor, was found to be fully functional. The ZmAFB2/3 b1 auxin receptor was found to be more sensitive to hormone than AtAFB2 and allowed for rapid circuit activation upon auxin addition. These results validate the conserved role of predicted auxin response genes in maize, as well as provide evidence that a synthetic approach can facilitate broader comparative studies across the wide range of species with sequenced genomes.

scholarly journals Synthesis and properties of new fused pyrrolo-1,10-phenanthroline type derivatives

2021 ◽  
pp. 57-57
Author(s):  
Cristina Al-Matarneh ◽  
Irina Rosca ◽  
Sergiu Shova ◽  
Ramona Danac
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Spectroscopic Data ◽  
Molecular Structures ◽  
Dipolar Cycloaddition ◽  
Synthetic Approach ◽  
Good Activity ◽  
Substituted Acetylenes ◽  
Potential Antimicrobial Activity

New fused pyrrolo-phenanthroline type derivatives were synthesized, in two steps, from 1,10-phenanthroline and evaluated for antimicrobial activity and fluorescence properties. Our synthetic approach involved a 3+2 dipolar-cycloaddition of some selected N-substituted 1,10-phenanthrolin-1-ium ylides, (m)ethoxycarbonyl and cyano (1,2-di)substituted acetylenes and alkenes, respectively. The structures of compounds were supported by analytical and spectroscopic data. Molecular structures of four compounds have also been also determined by monocrystal XRD analyses. All synthesized compounds were then evaluated for their potential antimicrobial activity against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922 and Candida albicans ATCC10231. Two of the compounds demonstrated good activity against the above tested strains.

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