scholarly journals Preparation of a Z-Iodoalkene through Stork-Zhao-Wittig Olefination, Stereo-retentive Lithium–iodine Exchange and Z-Boronic acid Pinacol Ester Synthesis

2020 ◽  
Vol 97 ◽  
pp. 217-231
Author(s):  
Mathieu A. Morin
Keyword(s):  
Boronic Acid ◽  
Ester Synthesis ◽  
Wittig Olefination

A Boronic Acid-Based Fluorescence Hydrogel for Monosaccharide Detection

2018 ◽  
Author(s):  
Suying Xu ◽  
Adam Sedgwick ◽  
Souad Elfecky ◽  
Wenbo Chen ◽  
Ashley Jones ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Boronic Acid ◽  
Binding Constants ◽  
Strong Fluorescence ◽  
Fluorescence Response ◽  
Turn On ◽  
Fluorescence Turn On ◽  
Hydrogel System

<p>A boronic acid-based anthracene fluorescent probe was functionalised with an acrylamide unit to incorporate into a hydrogel system for monosaccharide detection<i>. </i>In solution, the fluorescent probe<b> </b>displayed a strong fluorescence turn-on response upon exposure to fructose, and an expected trend in apparent binding constants, as judged by a fluorescence response where D-fructose > D-galactose > D-mannose > D-glucose. The hydrogel incorporating the boronic acid monomer demonstrated the ability to detect monosaccharides by fluorescence with the same overall trend as the monomer in solution with the addition of fructose resulting in a 10-fold enhancement (≤ 0.25 M). <b><u></u></b></p>

Theoretical Studies of the Acid-Base Equilibria in a Model Active Site of the Human 20S Proteasome

2020 ◽  
Author(s):  
Jon Uranga ◽  
Lukas Hasecke ◽  
Jonny Proppe ◽  
Jan Fingerhut ◽  
Ricardo A. Mata
Keyword(s):  
Active Site ◽  
Boronic Acid ◽  
Computational Study ◽  
Ubiquitin Proteasome System ◽  
Bayesian Optimization ◽  
Inhibition Mechanism ◽  
20S Proteasome ◽  
Acid Base ◽  
Ubiquitin Proteasome ◽  
Infection Cycles

The 20S Proteasome is a macromolecule responsible for the chemical step in the ubiquitin-proteasome system of degrading unnecessary and unused proteins of the cell. It plays a central role both in the rapid growth of cancer cells as well as in viral infection cycles. Herein, we present a computational study of the acid-base equilibria in an active site of the human proteasome, an aspect which is often neglected despite the crucial role protons play in the catalysis. As example substrates, we take the inhibition by epoxy and boronic acid containing warheads. We have combined cluster quantum mechanical calculations, replica exchange molecular dynamics and Bayesian optimization of non-bonded potential terms in the inhibitors. In relation to the latter, we propose an easily scalable approach to the reevaluation of non-bonded potentials making use of QM/MM dynamics information. Our results show that coupled acid-base equilibria need to be considered when modeling the inhibition mechanism. The coupling between a neighboring lysine and the reacting threonine is not affected by the presence of the inhibitor.

Arylboronic Acids in Self-condensation of Glucosamines Forming Deoxyfructosazine, Catalysts or Reagents?

2019 ◽  
Author(s):  
Meifeng Wang ◽  
Gan Zhu ◽  
Yiqun Li ◽  
Liuqun Gu
Keyword(s):  
Molecular Recognition ◽  
Boric Acid ◽  
Boronic Acid ◽  
Catalytic Mechanism ◽  
Organic Transformations ◽  
Food Industries ◽  
Arylboronic Acids ◽  
Excess Amount ◽  
Phenyl Boronic Acid ◽  
Boron Acid

Arylboronic acids were widely used as efficient catalysts in direct amide formation and other organic transformations. Surprisingly, reports on their use as catalysts in carbohydrates synthesis are very rare even though boron acid-diol complexation was extensively investigated in molecular recognition for saccharides and so on. Here we developed an efficient arylboronic acids catalyzed dimerization of glucosamines forming deoxyfructosazine which is important compound in pharmaceutical and food industries, against a commonly held belief that excess amount of phenyl boronic acid (or boric acid) is a must. A catalytic mechanism was also proposed and arylboronic acids instead of their boronates was identified as catalysts.

Construction the A-B bicyclic ring structure of Stemocurtisisne

2020 ◽  
Vol 17 ◽  
Author(s):  
Duc Dau Xuan
Keyword(s):  
Glutamic Acid ◽  
Natural Product ◽  
Mannich Reaction ◽  
Boronic Acid ◽  
Ring Opening ◽  
Ring Structure ◽  
Starting Material ◽  
Epoxide Ring ◽  
Epoxide Ring Opening

: The synthesis of the A-B bicyclic ring structure 3 of the natural product Stemocurtisine is described. The synthesis was accomplished in seven synthetic steps from commercially available L-glutamic acid. The key step involved a borono-Mannich reaction between the hemiaminal 6 and trans-β-styryl boronic acid and trans-β-styrylpotassiumtrifluoroborate to prepare the cis diene 4. Attempts to prepare the A-B-C ring compound 2 via intramolecular epoxide ring opening followed by rearangement under different basic conditions were unsuccessful. Only unreactive starting material was recovered.

scholarly journals THE ROLE OF LYMPH CHOLESTEROL IN THE REGULATION OF ENDOGENOUS CHOLESTEROL AND CHOLESTEROL ESTER SYNTHESIS

1958 ◽  
Vol 230 (2) ◽  
pp. 631-641
Author(s):  
Leon Swell ◽  
E.C. Trout ◽  
Henry Field ◽  
C.R. Treadwell
Keyword(s):  
Cholesterol Ester ◽  
Ester Synthesis ◽  
Endogenous Cholesterol
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