scholarly journals Azoacetylenes for the Synthesis of Arylazotriazole Photoswitches

2021 ◽  
Author(s):  
Patrick Pfaff ◽  
Felix Anderl ◽  
Moritz Fink ◽  
Moritz Balkenhohl ◽  
Erick Carreira
Keyword(s):  
Natural Products ◽  
Arachidonic Acid ◽  
Modular Approach ◽  
Complex Molecules ◽  
Design And Synthesis ◽  
Wide Range ◽  
Potential Applications ◽  
First Time ◽  
Oriented Approach

We report a modular approach towards novel arylazotriazole photoswitches and their photophysical characterization. Addition of lithiated TIPS-acetylene to aryldiazonium tetrafluoroborate salts gives a wide range of azoacetylenes, constituting an underexplored class of stable intermediates. <i>In situ </i>desilylation transiently leads to terminal arylazoacetylenes that undergo copper-catalyzed cycloadditions (CuAAC) with a diverse collection of organoazides. These include complex molecules derived from natural products or drugs, such as colchicine, taxol, tamiflu, and arachidonic acid. The arylazotriazoles display near-quantitative photoisomerization and long thermal <i>Z</i>-half-lives. Using the method, we introduce for the first time the design and synthesis of a diacetylene platform that permits implementation of a consecutive and diversity-oriented approach linking two different conjugants to independently addressable acetylenes within a common photoswitchable azotriazole. This is showcased in the synthesis of several photoswitchable conjugates, with potential applications as photoPROTACs and photoswitchable biotin conjugates

scholarly journals Azoacetylenes for the Synthesis of Arylazotriazole Photoswitches

2021 ◽  
Author(s):  
Patrick Pfaff ◽  
Felix Anderl ◽  
Moritz Fink ◽  
Moritz Balkenhohl ◽  
Erick Carreira
Keyword(s):  
Natural Products ◽  
Arachidonic Acid ◽  
Modular Approach ◽  
Complex Molecules ◽  
Design And Synthesis ◽  
Wide Range ◽  
Potential Applications ◽  
First Time ◽  
Oriented Approach

We report a modular approach towards novel arylazotriazole photoswitches and their photophysical characterization. Addition of lithiated TIPS-acetylene to aryldiazonium tetrafluoroborate salts gives a wide range of azoacetylenes, constituting an underexplored class of stable intermediates. <i>In situ </i>desilylation transiently leads to terminal arylazoacetylenes that undergo copper-catalyzed cycloadditions (CuAAC) with a diverse collection of organoazides. These include complex molecules derived from natural products or drugs, such as colchicine, taxol, tamiflu, and arachidonic acid. The arylazotriazoles display near-quantitative photoisomerization and long thermal <i>Z</i>-half-lives. Using the method, we introduce for the first time the design and synthesis of a diacetylene platform that permits implementation of a consecutive and diversity-oriented approach linking two different conjugants to independently addressable acetylenes within a common photoswitchable azotriazole. This is showcased in the synthesis of several photoswitchable conjugates, with potential applications as photoPROTACs and photoswitchable biotin conjugates

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

scholarly journals In situ Impact of the Antagonistic Fungal Strain, Trichoderma gamsii T30 on the Plant Pathogenic Fungus, Rhizoctonia solani in Soil

2019 ◽  
Vol 68 (2) ◽  
pp. 211-216
Author(s):  
MUHAMMAD ANEES ◽  
MUHAMMAD ABID ◽  
SOBIA CHOHAN ◽  
MUHAMMAD JAMIL ◽  
NADEEM AHMED ◽  
...  
Keyword(s):  
Population Density ◽  
Rhizoctonia Solani ◽  
Pathogenic Fungus ◽  
Suppressive Effect ◽  
Fungal Strain ◽  
Soil Microbiome ◽  
Target Dna ◽  
Wide Range ◽  
First Time

Rhizoctonia solani is a soil-borne fungus causing a wide range of plants diseases. Trichoderma gamsii strain T30 has previously been reported as antagonistic against R. solani. Although there are a few studies about the influence of Trichoderma strains on the R. solani densityin a pathosystem in the presence of plant hosts, this report for the first time comprehensively describes in situ effects of a T. gamsii strain on the population density of R. solani in the soil microcosmic conditions. The population dynamics of R. solani were followed in the autoclaved and non-autoclaved soils in artificially prepared microcosms up to day 25 after co-inoculation with T. gamsii in the variable ratios (R1/T1; R1/T0.1; R1/T0.01 of R. solani/T. gamsii). The population density of R. solani was evaluated by qPCR. In the autoclaved soil, target DNA copies of R. solani increased in the control samples from 1 × 105 to 6.5 × 106. At R1/T0.01, the number of target DNA copies were not significantly changed until day 11; however, it decreased by around five times at day 25. At R1/T0.1 and R1/T1, the number of DNA copies was reduced to 2.1 × 106 and 7.6 × 105 at day 11, respectively and the reduction was as much as 17 times at day 25. In the non-autoclaved soil, the number of the fungal cells decreased at day 25 whether inoculated or not with Trichoderma indicating a general suppression by the soil microbiome. In brief, T. gamsii significantly inhibited the growth of R. solani in the soil in situ and there was a general suppressive effect of the natural microbiome.

scholarly journals Formation of Bifunctional Octasilsesquioxanes via Silylative Coupling and Cross-Metathesis Reaction

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3966
Author(s):  
Małgorzata Bołt ◽  
Patrycja Żak ◽  
Beata Dudziec ◽  
Anna Schulmann ◽  
Bogdan Marciniec
Keyword(s):  
Functional Materials ◽  
Metathesis Reaction ◽  
One Pot ◽  
Intermediate Products ◽  
Design And Synthesis ◽  
Cross Metathesis ◽  
Synthetic Procedure ◽  
Wide Range ◽  
Potential Applications ◽  
New Compounds

Bifunctional silsesquioxanes create an attractive group of compounds with a wide range of potential applications, and recently they have gained much interest. They are known to be obtained mainly via hydrosilylation, but we disclose novel synthetic protocols based on different but complementary reactions, i.e., cross-metathesis (CM) and silylative coupling (SC). A series of cubic T8 type silsesquioxane derivatives with a broad scope of styryl substituents were synthesized in a one-pot procedure and characterized by spectroscopic and spectrometric methods. All of the new compounds can be obtained in a one-pot manner, which has an attractive impact on the synthetic procedure, as it is economic in terms of the isolation of intermediate products. Additionally, the methodology disclosed here enables the (E)-stereoselective introduction of styrenes derivative to the cubic T8 type core. The presented compounds can be interesting precursors for a further functionalization that may significantly increase the possibility of their application in the design and synthesis of new functional materials.

Unique heliophysics science opportunities along the Interstellar Probe journey up to 1000 AU from the Sun

2021 ◽  
Author(s):  
Elena Provornikova ◽  
Pontus C. Brandt ◽  
Ralph L. McNutt, Jr. ◽  
Robert DeMajistre ◽  
Edmond C. Roelof ◽  
...  
Keyword(s):  
Space Mission ◽  
In Situ Measurements ◽  
Unique Determination ◽  
The Sun ◽  
Global Shape ◽  
Wide Range ◽  
First Time ◽  
Interstellar Probe ◽  
Probe Mission

&lt;p&gt;The Interstellar Probe is a space mission to discover physical interactions shaping globally the boundary of our Sun`s heliosphere and its dynamics and for the first time directly sample the properties of the local interstellar medium (LISM). Interstellar Probe will go through the boundary of the heliosphere to the LISM enabling for the first time to explore the boundary with a dedicated instrumentation, to take the image of the global heliosphere by looking back and explore in-situ the unknown LISM. The pragmatic concept study of such mission with a lifetime 50 years that can be implemented by 2030 was funded by NASA and has been led by the Johns Hopkins University Applied Physics Laboratory (APL). The study brought together a diverse community of more than 400 scientists and engineers spanning a wide range of science disciplines across the world.&lt;/p&gt;&lt;p&gt;Compelling science questions for the Interstellar Probe mission have been with us for many decades. Recent discoveries from a number of space missions exploring the heliosphere raised new questions strengthening the science case. The very shape of the heliosphere, a manifestation of complex global interactions between the solar wind and the LISM, remains the biggest mystery. Interpretations of imaging the heliosphere in energetic neutral atoms (ENAs) in different energy ranges on IBEX and Cassini/INCA from inside show contradictory pictures. Global physics-based models also do not agree on the global shape. Interstellar Probe on outbound trajectory will image the heliosphere from outside for the first time and will provide a unique determination of the global shape.&lt;/p&gt;&lt;p&gt;The LISM is a completely new area for exploration and discovery. We have a crude understanding of the LISM inferred from in-situ measurements inside the heliosphere of interstellar helium, pick-up-ions, ENAs, remote observations of solar backscattered Lyman-alpha emission and absorption line spectroscopy in the lines of sight of stars. We have no in-situ measurements of most LISM properties, e.g. ionization, plasma and neutral gas, magnetic field, composition, dust, and scales of possible inhomogeneities. Voyagers with limited capabilities have explored 30 AU beyond the heliosphere which appeared to be a region of significant heliospheric influence. The LISM properties are among the key unknowns to understand the Sun`s galactic neighborhood and how it shapes our heliosphere. Interstellar Probe will be the first NASA mission to discover the very nature of the LISM and shed light on whether the Sun enters a new region in the LISM in the near future.&lt;/p&gt;&lt;p&gt;In this presentation we give an overview of heliophysics science for the Interstellar Probe mission focusing on the critical science questions of the three objectives for the mission. We will discuss in more details a need for direct measurements in the LISM uniquely enabled by the Interstellar Probe.&lt;/p&gt;

Efficient Access to Aliphatic Esters by Photocatalyzed Alkoxycarbonylation of Alkenes

2021 ◽  
Author(s):  
Jian-Qiang Chen ◽  
Xiaodong Tu ◽  
Qi Tang ◽  
Ke Li ◽  
Liang Xu ◽  
...  
Keyword(s):  
Natural Product ◽  
Oxalyl Chloride ◽  
Biologically Active ◽  
Formal Synthesis ◽  
Efficient Access ◽  
Wide Range ◽  
New Strategy ◽  
Aliphatic Esters ◽  
First Time

Abstract Aliphatic esters are essential constituents of biologically active compounds and versatile chemical intermediates for the synthesis of drugs. However, their preparation from readily available olefins remains challenging. In this report, a new strategy to access aliphatic esters from olefins through a unique photocatalyzed alkoxycarbonylation reaction is described. Alkyloxalyl chlorides, generated in situ from the corresponding alcohols and oxalyl chloride, are engaged for the first time as alkoxycarbonyl radical fragments under photoredox catalysis. This transformation tolerates a broad scope of electron-rich and electron-deficient olefins and provides the corresponding β-chloro esters in good yields. Additionally, a formal β-selective alkene alkoxycarbonylation is developed. And, a variety of oxindole-3-acetates and furoindolines are prepared in good to excellent yields. A more concise formal synthesis of (±)-physovenine is accomplished as well. With these strategies, a wide range of natural-product-derived olefins and alkyloxalyl chlorides are also successfully employed.

scholarly journals The use of in-situ produced cosmogenic radionuclides in glaciology and glacial geomorphology

1999 ◽  
Vol 28 ◽  
pp. 103-110 ◽  
Author(s):  
Derek Fabel ◽  
Jon Harbor
Keyword(s):  
Model Development ◽  
Temporal Variations ◽  
Age Dating ◽  
Cosmogenic Radionuclides ◽  
Glacial Geomorphology ◽  
Wide Range ◽  
Erosion Models ◽  
Potential Applications ◽  
Cosmogenic Radionuclide

AbstractThe usefulness of in-situ produced cosmogenic radionuclides in constraining glacial chronologies through exposure-age dating has been demonstrated in numerous studies. However, an understanding of cosmogenic radionuclide techniques and their uncertainties opens up a wide range of other potential applications in glaciology and glacial geomorphology. Recently developed applications include: estimation of spatial and temporal variations in the depth of glacial erosion from cosmogenic radionuclide inheritance, which provides important constraints on process-based erosion models; and burial dating, which can provide chronological control for glacial advances and the onset of till deposition. An interesting new application, currently at the level of theoretical model development, concerns the unraveling of complex exposure and burial histories. Overall, in-situ produced cosmogenic radionuclide techniques provide a means with which to constrain a wide range of ice-sheet and glacial models over time-scales of a thousand to a few million years.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

A Novel Injectable Chitosan Sponge Containing Brain Derived Neurotrophic Factor (BDNF) to Enhance Human Oligodendrocyte Progenitor Cells' (OPC) Differentiation

2014 ◽  
Vol 1621 ◽  
pp. 127-132
Author(s):  
Mina Mekhail ◽  
Qiao-Ling Cui ◽  
Guillermina Almazan ◽  
Jack Antel ◽  
Maryam Tabrizian
Keyword(s):  
Progenitor Cells ◽  
Spinal Cord Injuries ◽  
Cell Types ◽  
Therapeutic Modality ◽  
Oligodendrocyte Progenitor Cells ◽  
High Porosity ◽  
Oligodendrocyte Progenitor ◽  
Wide Range ◽  
First Time

ABSTRACTWe developed a rapidly-gelling chitosan sponge crosslinked with Guanosine 5'-Diphosphate (GDP). GDP has not been previously explored as an anionic crosslinker, and it was used in this application since the nucleoside guanosine has been shown to improve remyelination in situ, and thus its presence in the sponge composition was hypothesized to induce Oligodendrocyte Progenitor Cells' (OPC) differentiation. In addition to the chemical composition tailored to target OPCs, the developed chitosan sponge possesses a wide range of desirable physicochemical properties such as: rapid gelation, high porosity with interconnected pores, moduli of elasticity resembling that of soft tissue and cytocompatibility with many cell types. Moreover, protein encapsulation into the sponges was possible with high encapsulation efficiencies (e.g. BMP-7 and NT-3). In this study, BDNF was encapsulated in the chitosan sponges with an encapsulation efficiency greater than 80% and a sustained release over a 16-day period was achieved. We demonstrate here for the first time, the attachment of human fetal OPCs to the sponges and their differentiation after 12 days of culture. Overall, this newly-introduced injectable sponge is a promising therapeutic modality that can be used to enhance remyelination post-spinal cord injuries.

scholarly journals Effect of Fe3O4 and TiO2 Nanoparticles on Catalase Activity and β-Carotene Content at Pigmented Yeast Strain Rhodotorula gracilis

2017 ◽  
Vol 21 (1) ◽  
pp. 35-40
Author(s):  
Agafia Usatîi ◽  
Alina Beșliu ◽  
Nadejda Efremova
Keyword(s):  
Catalase Activity ◽  
Yeast Strain ◽  
Carotene Content ◽  
Wide Range ◽  
Rhodotorula Gracilis ◽  
Potential Applications ◽  
First Time ◽  
Antioxidant Enzyme Catalase ◽  
Β Carotene

AbstractThe properties of nanoparticles have been used in a wide range of potential applications in food industry, medicine, microbial biotechnology, cosmetics, environmental production. Research results of evaluation of the effect of Fe3O4and TiO2nanoparticles applicated in large concentration limits on some parameters of pigmented yeast strainRhodotorula gracilisCNMN-Y-30 are presented in this paper. It was established that nanoparticles selected for study caused toxic effects on β-caroten accumulation and activity of antioxidant enzyme catalase depending on concentration and nanostructure. The strong correlation between concentration of nanoparticles and evaluated components has been revealed at studied yeast strain. Coefficients of correlation varied in limits R2= 0.623... 0.951. For the first time, the determination of β-carotene accumulation and catalase activity rate as functional tests for estimation of toxicity of nanoparticles for pigmented yeast strainRhodotorula graciliswas effectuated. Thus, it was established that adaptive response of yeast strain to the presence of Fe3O4and TiO2nanoparticles has been manifested by modification of the processes of β-carotene biosythesis and catalase activity.

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