bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 2,3‐Diaryl‐2
H
‐Azirines via Cs
2
CO
3
‐Mediated Cyclization of Ketoxime Acetates
Authors: Zhao Mi‐Na , Guan* Zheng‐Hui 
Published: April 2020

Abstract

This article describes the procedure for synthesis of 2,3‐diaryl‐2
H
‐azirines via Cs
2
CO
3
‐mediated cyclization of ketoxime acetates. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. The synthetic approach to 2
H
‐azirines is relied on thermal/photochemical rearrangement of vinyl azides or Neber reaction. The salient features of this method include easily available starting materials, broad functional group compatibility, and mild reaction conditions. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Synthesis of 4‐Methylbenzoate(2′,4′,6′‐Trimethoxy‐Phenyl)Iodonium Tosylate
Authors: Seidl Thomas L. , Moment* Aaron , Orella Charles , Vickery Thomas , Stuart* David R. 
Published: April 2020

Abstract
This article describes the procedure for synthesis of 4‐Methylbenzoate(2’,4’,6’‐trimethoxyphenyl)iodonium Tosylate. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. Unsymmetrical diaryliodonium salts that selectively, and predictably, transfer one aryl group over the other are particularly desirable reagents, especially for the transfer of elaborate aryl groups to nucleophilic moieties. Aryl(trimethoxyphenyl)iodonium tosylates undergo facile anion exchange with other anions under aqueous conditions to generate the corresponding aryl(trimethoxyphenyl)iodonium bromides, iodide, trifluoroacetates, triflates, tetrafluoroborates, and hexafluorophosphates. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Discussion Addendum For: Synthesis of Highly Enantiomerically Enriched Amines by Asymmetric Transfer Hydrogenation of
N‐
(
tert
‐Butylsulfinyl) Imines
Authors: Yus* Miguel 
Published: April 2020

Abstract
This discussion addendum describes the procedure for synthesis of highly enantiomerically enriched amines by asymmetric transfer hydrogenation of N‐tert‐butylsulfinyl imines. It is believed that more than 75% of all drugs and drug candidates contain the amine functionality. In many cases, especially natural products, aminated compounds possess at least one stereogenic center, so asymmetric methodologies that provide chiral amines enantioselectively are of great synthetic importance. The starting enantiomerically pure N‐tert‐butylsulfinyl imines are easily prepared by mixing the corresponding carbonyl compounds with enantiomerically pure commercially available tert‐butanesulfinamides in the presence of a Lewis acid, titanium tetraethoxide being the most commonly used, under thermal or microwave activation. Transfer hydrogenation to chiral imines, followed by desulfinylation under acidic conditions, is a versatile and useful methodology for the preparation of a wide range of enantioenriched primary α,α‐disubstituted amines.
Synthesis of Chiral Diamine Ligands for Nickel‐Catalyzed Asymmetric Cross‐Couplings of Alkylchloroboronate Esters with Alkylzincs: (1
R
,2
R
)‐
N
,
N
′‐Dimethyl‐1,2‐Bis(2‐Methylphenyl)‐1,2‐Diaminoethane
Authors: Masuda Yusuke , Fu* Gregory C. 
Published: April 2020

Abstract
This article describes the procedure for synthesis of chiral diamine ligands for nickel‐catalyzed asymmetric cross‐couplings of alkylchloroboronate esters with alkylzincs. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. Chiral N,N'‐dimethyl‐1,2‐diphenylethylene‐1,2‐diamine (DMPEDA) and its derivatives are used as chiral ligands for metal‐catalyzed asymmetric reactions. The use of chiral DMPEDA‐type ligands enables the enantioconvergent cross‐coupling of racemic alkyl halides with various organometallic compounds. The procedure for the synthesis of 1,2‐bis(2‐methylphenyl)‐1,2‐diaminoethane is based on the method reported by J. J. Chin and co‐workers. A series of diphenylethylenediamine derivatives is synthesized from a single diamine (1,2‐bis‐(2‐hydroxyphenyl)‐1,2‐diaminoethane) with this method. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Preparation of 5‐(Triisopropylalkynyl) Dibenzo[
b
,
d
]Thiophenium Triflate
Authors: Waldecker Bernd , Kafuta Kevin , Alcarazo* Manuel 
Published: April 2020

Abstract
This article describes the procedure for preparation of 5‐(Triisopropylalkynyl) dibenzo[b,d]thiophenium triflate. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. Prior to performing each reaction, a thorough hazard analysis and risk assessment should be carried out with regard to each chemical substance and experimental operation on the scale planned and in the context of the laboratory where the procedures will be carried out. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Discussion Addendum For: Allylic Oxidation Catalyzed by Dirhodium(II) Tetrakis[ε‐Caprolactamate] of
tert
‐Butyldimethylsilyl‐Protected
trans
‐Dehydroandrosterone
Authors: Su Yong‐Liang , De Angelis Luca , Doyle* Michael P. 
Published: April 2020

Abstract

Allylic oxidation of alkenes, which converts an allylic methylene group to a carbonyl group, is powerful methodology for the synthesis of unsaturated ketones. Compared with more traditional oxidative reagents, such as stoichiometric oxidants selenium dioxide and chromium(VI), the mild
tert
‐butyl hydroperoxide (TBHP) oxidant, when combined with select transition metals, has advantages, especially in large‐scale reactions and natural product syntheses. The success of TBHP as a selective oxidant is due to formation of the
tert
‐butylperoxy radical. N‐Substituted 2,3‐dihydro‐4‐piperidones and substituted 4‐pyranone compounds are important intermediates in natural products and drug candidates. 7 In the first total synthesis of dehydroaltenuene B by the Barrett group, the authors found that alpha, beta‐unsaturated ketone, which was the key intermediate, could be obtained by TBHP allylic oxidation of fused cyclic alkene in good yield.
Preparation of 2,4,5,6‐Tetra(9H‐Carbazol‐9‐yl)Isophthalonitrile
Authors: Engle Saskia M. , Kirkner Takisha R. , Kelly* Christopher B. 
Published: April 2020

Abstract
This article describes the procedure for preparation of 2,4,5,6‐tetra(9H‐carbazol‐9‐yl) isophthalonitrile. It presents some of the important points to be considered, the conditions that need to be maintained, characterization data, and the reagents required, as well as the techniques used and the equipment setup that are vital to carrying out the process. Prior to performing each reaction, a thorough hazard analysis and risk assessment should be carried out with regard to each chemical substance and experimental operation on the scale planned and in the context of the laboratory where the procedures will be carried out. The article also describes the hazards associated with working with chemicals and the ways to deal with these hazards.
Synthesis of Chiral Tetramic Acids: Preparation of (
S
)‐5‐Benzylpyrrolidine‐2,4‐Dione from L‐Phenylalanine Methyl Ester Hydrochloride
Authors: Lambert* Kyle M. , Medley Austin W. , Jackson Amy C. , Markham Lauren E. , Wood John L. 
Published: April 2020

Abstract
This article describes the procedure for the synthesis of chiral tetramic acids by preparation of (S)‐5‐benzylpyrrolidine‐2,4‐dione from L‐phenylalanine methyl ester hydrochloride. It presents some important points to be considered before carrying out the procedure. The tetramic acid (pyrrolidine‐2,4‐dione) scaffold can be found embedded within a plethora of natural products which exhibit a wide range of bioactivities, including powerful antibiotic, antiviral, cytotoxic, and fungicidal properties, as well as inhibition of tumor growth. The article provides a general overview of tetramic acid chemistry and highlights the utility of developed synthetic methodologies aimed at the construction of the pyrrolidine‐2,4‐dione core as well as the challenges encountered when applying these methods towards more complex systems. It also presents a discussion on the application of tetramic acids and the Lacey‐Dieckmann cyclization to total synthesis.
A Noble‐Transition Alloy Excels at Hot‐Carrier Generation in the Near Infrared
Authors: Stofela Sara K. F. , Kizilkaya Orhan , Diroll Benjamin T. , Leite Tiago R. , Taheri Mohammad M. , Willis Daniel E. , Baxter Jason B. , Shelton William A. , Sprunger Phillip T. , McPeak Kevin M. 
Published: April 2020

AbstractAbove‐equilibrium “hot”‐carrier generation in metals is a promising route to convert photons into electrical charge for efficient near‐infrared optoelectronics. However, metals that offer both hot‐carrier generation in the near‐infrared and sufficient carrier lifetimes remain elusive. Alloys can offer emergent properties and new design strategies compared to pure metals. Here, it is shown that a noble‐transition alloy, AuxPd1−x, outperforms its constituent metals concerning generation and lifetime of hot carriers when excited in the near‐infrared. At optical fiber wavelengths (e.g., 1550 nm), Au50Pd50 provides a 20‐fold increase in the number of ≈0.8 eV hot holes, compared to Au, and a threefold increase in the carrier lifetime, compared to Pd. The discovery that noble‐transition alloys can excel at hot‐carrier generation reveals a new material platform for near‐infrared optoelectronic devices.
Comparative Study of Zeolite L Etching with Ammonium Fluoride and Ammonium Bifluoride Solutions
Authors: Babić Viktoria , Tang Lingxue , Qin Zhengxing , Hafiz Leila , Gilson Jean‐Pierre , Valtchev Valentin 
Published: April 2020

AbstractA commercial zeolite L is subjected to chemical etching with aqueous solutions of NH4F and NH4HF2 to generate secondary porosity. The derived samples are characterized by X‐ray diffraction, N2 adsorption, scanning, and transmission electron microscopy, 27Al MAS NMR, thermogravimetric analysis, and their acid sites are quantified by FTIR spectroscopy of adsorbed basic probe molecules. The catalytic properties of the pristine and modified zeolites are evaluated in the dealkylation of 1,3,5‐triisopropylbenzene. Tuning the etching conditions allows to generate hierarchical zeolites without losing micropore volume. Furthermore, both fluoride etchants do not change the acid properties of the zeolite substantially, which is confirmed by chemical composition analysis (ICP‐OES) and by FTIR spectroscopy of pyridine. The dissolution rate of zeolite L is much faster with NH4HF2 than NH4F. The set of experimental data shows that the 1 wt% NH4HF2 solution is an efficient etchant able to generate mesopores without affecting the parent zeolite properties as lower amounts of fluoride source are required than with concentrated (20–40 wt%) NH4F solutions.
Selenium‐Doped Carbon Quantum Dots Act as Broad‐Spectrum Antioxidants for Acute Kidney Injury Management
Authors: Rosenkrans Zachary T. , Sun Tuanwei , Jiang Dawei , Chen Weiyu , Barnhart Todd E. , Zhang Ziyi , Ferreira Carolina A. , Wang Xudong , Engle Jonathan W. , Huang Peng , Cai Weibo 
Published: April 2020

AbstractThe manifestation of acute kidney injury (AKI) is associated with poor patient outcomes, with treatment options limited to hydration or renal replacement therapies. The onset of AKI is often associated with a surfeit of reactive oxygen species. Here, it is shown that selenium‐doped carbon quantum dots (SeCQDs) have broad‐spectrum antioxidant properties and prominent renal accumulation in both healthy and AKI mice. Due to these properties, SeCQDs treat or prevent two clinically relevant cases of AKI induced in murine models by either rhabdomyolysis or cisplatin using only 1 or 50 µg per mouse, respectively. The attenuation of AKI in both models is confirmed by blood serum measurements, kidney tissue staining, and relevant biomarkers. The therapeutic efficacy of SeCQDs exceeds amifostine, a drug approved by the Food and Drug Administration that also acts by scavenging free radicals. The findings indicate that SeCQDs show great potential as a treatment option for AKI and possibly other ROS‐related diseases.
Recent Progress in Electrocatalysts for Acidic Water Oxidation
Authors: Lei Zhanwu , Wang Tanyuan , Zhao Bote , Cai Wenbin , Liu Yang , Jiao Shuhong , Li Qing , Cao Ruiguo , Liu Meilin 
Published: April 2020

AbstractHydrogen is a clean and renewable energy carrier for powering future transportation and other applications. Water electrolysis is a promising option for hydrogen production from renewable resources such as wind and solar energy. To date, tremendous efforts have been devoted to the development of electrocatalysts and membranes for water electrolysis technology. In principle, water electrolysis in acidic media has several advantages over that in alkaline media, including favorable reaction kinetics, easy product separation, and low operating pressure. However, acidic water electrolysis poses higher requirements for the catalysts, especially the ones for the oxygen evolution reaction. It is a grand challenge to develop highly active, durable, and cost‐effective catalysts to replace precious metal catalysts for acidic water oxidation. In this article, an overview is presented of the latest developments in design and synthesis of electrocatalysts for acidic water oxidation, emphasizing new strategies for achieving high electrocatalytic activity while maintaining excellent durability at low cost. In particular, the reaction pathways and intermediates are discussed in detail to gain deeper insight into the oxygen evolution reaction mechanism, which is vital to rational design of more efficient electrocatalysts. Further, the remaining scientific challenges and possible strategies to overcome them are outlined, together with perspectives for future‐generation electrocatalysts that exploit nanoscale materials for water electrolysis.
Enantioselektive Synthese von 3‐Fluorchromanen durch Iod(I)/Iod(III)‐Katalyse
Authors: Sarie Jérôme C. , Thiehoff Christian , Neufeld Jessica , Daniliuc Constantin G. , Gilmour Ryan 
Published: April 2020

AbstractDas Chromangerüst findet sich in einer Vielzahl von kleinen, bioaktiven Molekülen, in denen die 3‐Position häufig oxidiert wird. Motiviert durch die Wichtigkeit dieser Position für die Wirksamkeit sowie die Bedeutung der Bioisosterie in der Wirkstoffforschung wurde eine Iod(I)/Iod(III)‐Katalysestrategie für den Zugang zu enantiomerenangereicherten 3‐Fluorchromanen entwickelt (bis zu 7:93 e.r.). Die In‐situ‐Erzeugung von ArIF2 ermöglicht die direkte Fluorzyklisierung von Allylphenylethern, um neue Molekülgerüste zu erzeugen, die den stereoelektronischen gauche‐Effekt zeigen. Mechanistische Untersuchungen unter Verwendung von deuterierten Substraten bestätigen einen stereospezifischen Prozess, der mit einem Reaktionsverlauf des Typs IIinv übereinstimmt.
Effiziente Umwandlung von Licht in chemische Energie: Gerichtete, chirale Photoschalter mit sehr hohen Quantenausbeuten
Authors: Moormann Widukind , Tellkamp Tobias , Stadler Eduard , Röhricht Fynn , Näther Christian , Puttreddy Rakesh , Rissanen Kari , Gescheidt Georg , Herges Rainer 
Published: April 2020

AbstractPhotochrome Systeme werden verwendet, um verschiedenste technische Funktionen wie z. B. Konversion von Lichtenergie, molekulare Motoren, Pumpen, Aktuatoren und Sensoren zu realisieren. Essentiell für praktischen Anwendungen sind eine effiziente Umwandlung von Licht in chemische Energie, eine starre Struktur für die Übertragung der molekularen Bewegung auf die Umgebung und eine gerichtete Bewegung während der Isomerisierung. Wir präsentieren einen neuen Typ eines photochromen Systems (Diindandiazocin), welches sichtbares Licht mit einer Effizienz von 18 % in chemische Energie umwandelt. Die Quantenausbeuten sind außerordentlich hoch mit >70 % für die cis‐trans‐Isomerisierung und 90 % für die Rückreaktion und somit höher als im biochemischen System Rhodopsin (64 %). Zwei Diastereomere (meso und Racemat) konnten in einer nur zweistufigen Synthese mit hohen Ausbeuten erhalten werden. Beide Isomere sind gerichtete Schalter mit hohen Umsatzraten (76–99 %), welche selbst nach mehreren tausend Schaltzyklen keine Ermüdung aufzeigten.
Efficient Conversion of Light to Chemical Energy: Directional, Chiral Photoswitches with Very High Quantum Yields
Authors: Moormann Widukind , Tellkamp Tobias , Stadler Eduard , Röhricht Fynn , Näther Christian , Puttreddy Rakesh , Rissanen Kari , Gescheidt Georg , Herges Rainer 
Published: April 2020

AbstractPhotochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back‐reaction and thus higher than the biochemical system rhodopsin (64 %). Two diastereomers (meso and racemate) were obtained in only two steps in high yields. Both isomers are directional switches with high conversion rates (76–99 %). No fatigue was observed after several thousands of switching cycles in both systems.
RNA interference‐mediated control of cigarette beetle, Lasioderma serricorne
Authors: Koo Jinmo , Chereddy Shankar C. R. R. , Palli Subba R. 
Published: April 2020

AbstractThe cigarette beetle (CB; Lasioderma serricorne) is a pest on many stored products including tobacco. Fumigation is the common control method currently used. However, the options for controlling this pest are limited, due to resistance issues and phasing out of currently used chemical insecticides. Here, we evaluated RNA interference (RNAi) as a potential method for controlling the CB. RNA isolated from different stages was sequenced and assembled into a transcriptome. The CB RNA sequences showed the highest homology with those in the red flour beetle, Tribolium castaneum. Orthologs of proteins known to function in RNAi pathway were identified in the CB transcriptome, suggesting that RNAi may work well in this insect. Also, 32P‐labeled double‐stranded RNA (dsRNA) injected into CB larvae and adults was processed to small interference RNAs. We selected 12 genes that were shown to be the effective RNAi targets in T. castaneum and other insects and identified orthologs of them in the CB by searching its transcriptome. Injection of dsRNA targeting genes coding for GAWKY, Kinesin, Sec23, SNF7, and 26S proteasome subunit 6B into the CB larvae caused 100% mortality. Feeding dsRNA targeting SNF7 and 26S proteasome subunit 6B by sucrose droplet assay induced more than 90% mortality, which is 1.8 times higher than the mortality induced by dsGFP control (53%). These data demonstrate an efficient RNAi response in CB, suggesting that RNAi could be developed as an efficient method to control this pest.
Subphysiological temperature induces pervasive alternative splicing in Chinese hamster ovary cells
Authors: Tzani Ioanna , Monger Craig , Motheramgari Krishna , Gallagher Clair , Hagan Ryan , Kelly Paul , Costello Alan , Meiller Justine , Floris Patrick , Zhang Lin , Clynes Martin , Bones Jonathan , Barron Niall , Clarke Colin 
Published: April 2020

AbstractRNA sequencing (RNASeq) has been widely used to associate alterations in Chinese hamster ovary (CHO) cell gene expression with bioprocess phenotypes; however, alternative messenger RNA (mRNA) splicing, has thus far, received little attention. In this study, we utilized RNASeq for transcriptomic analysis of a monoclonal antibody (mAb) producing CHO K1 cell line subjected to a temperature shift. More than 2,465 instances of differential splicing were observed 24 hr after the reduction of cell culture temperature. A total of 1,197 of these alternative splicing events were identified in genes where no changes in abundance were detected by standard differential expression analysis. Ten examples of alternative splicing were selected for independent validation using quantitative polymerase chain reaction in the mAb‐producing CHO K1 cell line used for RNASeq and a further two CHO K1 cell lines. This analysis provided evidence that exon skipping and mutually exclusive splicing events occur in genes linked to the cellular response to changes in temperature and mitochondrial function. While further work is required to determine the impact of these changes in mRNA sequence on cellular phenotype, this study demonstrates that alternative splicing analysis can be utilized to gain a deeper understanding of post‐transcriptional regulation in CHO cells during biopharmaceutical production.
Pharmacokinetic study of tanshinol and ligustrazine in rat plasma after intravenous administration of tanshinol and Danshen Chuanxiongqin Injection
Authors: Jiao Weijie , Lei Zhen , Zhao Xu , Wang Kun , Ma Ailing , Du Lei , Hou Ruiying , Han Jing , Chen Meng 
Published: April 2020

AbstractTo investigate the effect of ligustrazine on the pharmacokinetic profile of tanshinol after intravenous administration in rats, a sensitive liquid chromatography tandem mass spectrometry method was developed and validated for quantitative determination of tanshinol and ligustrazine in rat plasma. After prepared by protein precipitation, the analytes were separated on a Waters Acquity HSS T3 column (100 × 2.1 mm, 1.8μm) and eluted by 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 ml/min. The precursor–product ion transitions were m/z 197.0 → 135.0 for tanshinol, m/z 417.1 → 255.1 for liquiritin (internal standard) in negative ion mode and m/z 137.1 → 55.0 for ligustrazine in positive ion mode. To avoid the interference of tanshinol metabolite transformation, the stability of analytes in samples collected after administration was assessed. The validated method was successfully applied to a pharmacokinetic study after intravenous administration of single tanshinol and Danshen Chuanxiongqin Injection. After Danshen Chuanxiongqin injection administration, the values of elimination half‐time, area under the concentration–time curve and Co were 0.36 ± 0.13 h, 1.29 ± 0.37 μg/ml h and 10.51 ± 2.58 μg/ml for male rats, respectively. In the single tanshinol group, the corresponding values were 0.56 ± 0.24 h, 1.85 ± 0.44 μg/ml h and 14.11 ± 2.26 μg/ml for male rats—30–40% higher than those for the Danshen Chuanxiongqin Injection group. There was a significant different between male and female rats. This study provided information on the influence of ligustrazine on the pharmacokinetic characteristics of tanshinol after intravenous administration of Danshen Chuanxiongqin Injection in rats, which will be helpful for its clinical application.
Fluorodeoxyglucose positron emission tomography/computed tomography identifying pericardial metastasis from early‐stage p16‐positive oropharyngeal cancer
Authors: Shim Hye‐kyung , Kim Mi Ra , Lee Hongje 
Published: April 2020

AbstractPericardial metastasis from HPV‐positive oropharyngeal squamous cell carcinoma (OPSCC) without local recurrence is extremely rare. We report about a 69‐year‐old man exhibiting pericardial metastasis on positron emission tomography/computed tomography (PET/CT). There are currently no reports on the use of PET/CT in patients with pericardial metastasis from p16‐positive OPSCCs.