A general strategy based on luminescent oxygen channeling for the detection of adenosine in serum using the steric hindrance effect of thrombin

2014 ◽  
Vol 200 ◽  
pp. 19-24 ◽  
Author(s):  
Kai Zhang ◽  
Qianlu Yang ◽  
Xue Zhu ◽  
Ke Wang
Keyword(s):  
Steric Hindrance ◽  
General Strategy

Synthesizing highly fluorinated oligophenyls via Negishi coupling of fluoroarylzinc pivalates

Synthesis ◽  
2021 ◽  
Author(s):  
Julian Stoesser ◽  
Stefan Huber
Keyword(s):  
Steric Hindrance ◽  
Phosphine Ligands ◽  
Synthetic Methods ◽  
Lower Amount ◽  
General Strategy ◽  
Large Excess ◽  
Fluorine Substitution ◽  
Negishi Coupling ◽  
Organoboron Compounds

Previously established general synthetic methods for the synthesis of highly fluorinated biphenyls using Suzuki-Miyaura protocols require the use of organoboron compounds which are not very stable under reactions conditions and thus need to be used in large excess. Herein we report an improved general strategy for the synthesis of highly fluorinated biphenyls, terphenyls and phenyl-substituted terphenyls using organozinc pivalates. The influence of several parameters was investigated: a) in a series of different monodentate phosphine ligands, X-Phos showed the best performance; b) a higher yield could be obtained for substrates bearing less steric hindrance or lower amount of fluorine substitution; c) as iodinated substrates decomposed during the reaction, brominated electrophiles were found to be superior. The presented protocol is scalable, versatile, and works with commonly used and commercially available phosphine ligands (X Phos) and palladium sources (Pd2dba3). Also, it does not need excess nucleophile usage for terphenyl synthesis and only a slight such excess for the preparation of phenyl substituted terphenyls.

Steric hindrance-enforced distortion as a general strategy for the design of fluorescence “turn-on” cyanide probes

2013 ◽  
Vol 49 (86) ◽  
pp. 10136 ◽  
Author(s):  
Bin Chen ◽  
Yubin Ding ◽  
Xin Li ◽  
Weihong Zhu ◽  
Jonathan P. Hill ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
General Strategy ◽  
Turn On ◽  
Fluorescence Turn On

Steric hindrance influence of a diazo link upon mesogenic properties of some ligands and related copper complexes

1997 ◽  
Vol 94 ◽  
pp. 1695-1714 ◽  
Author(s):  
P Lesot ◽  
F Perez ◽  
P Judeinstein ◽  
JP Bayle ◽  
H Allouchi ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Copper Complexes

Towards Systematization

1977 ◽  
Vol 16 (03) ◽  
pp. 125-130 ◽  
Author(s):  
P. L. Reichertz
Keyword(s):  
Clinical Medicine ◽  
Medical Science ◽  
User Involvement ◽  
Empirical Science ◽  
Target System ◽  
General Strategy ◽  
System Construction ◽  
Formal Approach ◽  
Methodology Development ◽  
Planning Development

Data processing has become an important tool in theoretical and clinical medicine. The main categories of applications are : information analysis, (bio)signal processing and the field of information logistics (information systems).The problems encountered lie in the discrepancy of the basic methods of a formal approach to an empirical science, the complexity of the target system and the system ecology, i.e. the involvement of the user and the system environment during system construction and utilization.Possible solutions to these problems are the application of system techniques, inductive planning, development of medical methodology, development of methods and techniques for user involvement and assessment of motivation and education and educational planning.The necessary general strategy in the development in medical informatics is seen in the continuing systematization of the theoretical and practical approach. It is estimated that this will eventually contribute to the systematization of medical science and practice.

METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

1961 ◽  
Vol 36 (4) ◽  
pp. 511-519 ◽  
Author(s):  
Margaret Wiener ◽  
Charles I. Lupa ◽  
E. Jürgen Plotz
Keyword(s):  
Rat Liver ◽  
Human Placenta ◽  
Steric Hindrance ◽  
Placental Tissue ◽  
Caproic Acid ◽  
Major Product ◽  
Side Chain ◽  
Anaerobic Conditions ◽  
Prolonged Action ◽  
Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

Tetraphenylbenzene-based AIEgens: the Horizontally Oriented Emitters for highly Efficient Non-doped Deep Blue OLEDs and Host for High-Performance Hybrid WOLEDs

2020 ◽  
Author(s):  
Pengbo Han ◽  
Zeng Xu ◽  
Chengwei Lin ◽  
Dongge Ma ◽  
Anjun Qin ◽  
...  
Keyword(s):  
High Performance ◽  
General Strategy ◽  
Flat Panel Displays ◽  
Light Emitting ◽  
Horizontal Orientation ◽  
Deep Blue ◽  
Full Color ◽  
High Emission ◽  
White Oleds ◽  
Low Efficiency

Deep blue organic-emitting fluorophores are crucial for application in white lighting and full color flat-panel displays but emitters with high color quality and efficiency are rare. Herein, novel deep blue AIE luminogens (AIEgens) with various donor units and an acceptor of cyano substituted tetraphenylbenzene (TPB) cores were developed and used to fabricate non-doped deep blue and hybrid white organic light-emitting diodes (OLEDs). Benefiting from its high emission efficiency and high proportion of horizontally oriented dipoles in the film state, the non-doped deep blue device based on CN-TPB-TPA realized a maximum external quantum efficiency 7.27%, with a low efficiency roll-off and CIE coordinates of (0.15, 0.08). Moreover, efficient two-color hybrid warm white OLEDs (CIE<sub>x,y</sub> = 0.43, 0.45) were achieved using CN-TPB-TPA as the blue-emitting layer and phosphor doped host, which realized maximum current, power, external quantum efficiencies 58.0 cd A<sup>-1</sup>, 60.7 lm W<sup>-1</sup> and 19.1%, respectively. This work provides a general strategy to achieve high performance, stable deep blue and hybrid white OLEDs by construction of AIEgens with excellent horizontal orientation

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

A One-Pot Chemoenzymatic Synthesis of (2S,4R)-4-Methylproline Enables the First Total Synthesis of Antiviral Lipopeptide Cavinafungin B

2018 ◽  
Author(s):  
Christian R. Zwick ◽  
Hans Renata
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Complex Molecule ◽  
Molecular Target ◽  
Chemoenzymatic Synthesis ◽  
General Strategy ◽  
One Pot

We report an efficient ten-step synthesis of antiviral natural product cavinafungin B in 37% overall yield. By leveraging a one-pot chemoenzymatic synthesis of (2S,4R)-4-methylproline and oxazolidine-tethered (Rink-Boc-ATG-resin) SPPS methodology, the assembly of our molecular target could be conducted in an efficient manner.This general strategy could prove amenable to the construction of other natural and unnatural linear lipopeptides. The value of incorporating biocatalytic steps in complex molecule synthesis is highlighted by this work.

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

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