192. The structure and relative stabilities of boric esters of 1,2- and 1,3-diols

Hubert, Aurélia; Hargitay, B.; Dale, Johannes

doi:10.1039/jr9610000931

Cited by 38 publications

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“…To examine factors that affect the binding between boronic acids and diols, there is a need to have sensitive methods for the determination of their binding constants. Early methods include the pH-depression method 25,[41][42][43][44][45] and the B-NMR method. [46][47][48][49][50][51] These methods, although served the purpose for the early determination of binding constants between boronic acids and diols, are insensitive, require a large amount of sample, and take long experiment times.…”

Section: M E T H O D S F O R B I N D I N G C O N S T a N T S D E T mentioning

confidence: 99%

Boronolectins and fluorescent boronolectins: An examination of the detailed chemistry issues important for the design

Yan

Fang

Wang

2005

Medicinal Research Reviews

177

162

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Glycans in the form of glycoproteins or glycolipids play very critical roles in various biological and pathological processes including inflammation, cancer metastasis, immune reactions, embryo development, cell-cell communications and adhesions, blood generation, etc. Proteins (lectins) that can recognize carbohydrates have played very important roles in studying glycobiology. Small molecule mimics of lectins will be very useful in the development of new therapeutics and diagnostics. Along this line, boronic acids have been widely used in the design and synthesis of small organic compounds that mimic the function of lectins. This review examines in detail the factors that are important for the design of boronic acid-based lectin mimics, boronolectins.

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Section: M E T H O D S F O R B I N D I N G C O N S T a N T S D E T mentioning

confidence: 99%

Boronolectins and fluorescent boronolectins: An examination of the detailed chemistry issues important for the design

Yan

Fang

Wang

2005

Medicinal Research Reviews

177

162

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“…According to the experimental data reported in [18,19], the heat of formation of donor-acceptor complexes of 1,3,2-dioxaborinanes with amines is fairly small.…”

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confidence: 88%

Quantum-chemical study on conformations of molecular complexes formed by 2-methyl-1,3,2-dioxaborinane with methylamine

2009

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Conformations of 1 : 1 molecular complexes of 2-methyl-1,3,2-dioxaborinane with methylamine were studied in terms of restricted Hartree-Fock approximation using STO-3G, 3-21G, and 6-31G(d) bass sets. The results showed possible formation of two types of complexes, one with dative N→B bond, and the other with intermolecular hydrogen bond NH · · · O. Their relative stability and conformations are determined by both mutual orientation of the components and basis set used.The ability of boric acid esters to form molecular complexes with both lone electron pair (LEP) donors and acceptors [1] makes these compounds convenient models for computer simulation of mechanisms of interactions with various solvents. It was shown previously [2-7] that molecules of 2-alkyl-1,3,2-dioxaborinanes at room temperature undergo fast (on the NMR time scale) ring inversion with a relatively low barrier. In addition, the potential energy surface (PES) of 2-methyl-1,3,2-dioxaborinane (I) includes minima (energy-degenerate sofa conformers S) and a maximum corresponding to 2,5-twist conformer 2,5-T (Scheme 1) [8].culations, the formation of adducts by methyl-and phenylboronic acids with ammonia in solution is an endothermic processes [12]. In the present work we tried to simulate the potential energy surface of ester I in the presence of methylamine molecule in terms of the restricted Hartree-Fock approximation with STO-3G, 3-21G, and 6-31G(d) basis sets using HyperChem software package [13].We found that the molecular system 2-methyl-1,3,2-dioxaborinane (I)-methylamine (1 : 1) could give rise to numerous binary structures and that there are only two most stable associates with dative N→B bond (A) and intramolecular hydrogen bond H-N · · · O (B).

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“…The strained, five-membered ring is less stable than the six-rnembered one. This strain is relieved when the boron atom is converted into the tetraher Purification and Separation of Digoxin dral form [12]. This tetrahedral form is the prerequisite for the hydrolysis of the ester bond [21].…”

Section: R' Rzmentioning

confidence: 99%

Purification and Separation of Digoxin by Removal of Accompanying Glycosides as Phenylboronate Derivatives

Szeleczky¹,

Láng²

1980

Planta Med

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A new process has been developed for the purification and separation of digoxin from accompanying glycosides, utilizing their common feature of containing 1 , 3 4 0 1 units in their skeletons which can form cyclic esters with phenylboronic acid. As the polarity of the glycoside phenylboronates is substantially different from that of digoxin, they can be Separated easily.lntroduction Digoxin (Fig. I), a glycoside of greatest therapeutic importance as a cardiotonic, is isolated from the leaves of Digitalis lanata EHRH. The living plant contains the lanatosides predominantly in their primary form of aglycone-(digitoxose) 2-acetyldigitoxose-glucose [I]. In the Course of processing the plant, glucose is split off by the digilanidase enzyme and the acetyl group is hydrolyzed by the acetylase enzyme in the plant. As a result the drug also contains secondary glycosides of the type sttucture aglycone-(digitoxose), : digitoxin, digoxin, gitoxin and diginatin (Fig. I), as well as other glycosides present in minor quantities. The plant can also be processed in such a way that all glycosides are hydrolysed into their secondary forms.Digoxin may also be prepared by the microbial hydroxylation of digitoxin.In the Course of digitoxin transformation with microorganisms known to be able to hydroxylate in position 12ß, glycosides hydroxylated in position 7 ß are also formed as by-products: 7 P-hydroxydigitoxin and 7 P-hydroxydigoxin [2, 31.M. NATONEK et al. [3] hydroxylated digitoxin to digoxin as a main product using Streptomyces praecox strain MNG-127. The bioconversion was carried out at a substrate concentration of 500 pg digitoxin per millilitre broth. After a four day fermentation the digitoxin was transformed to digoxin with a conversion of Heruntergeladen von: University of British Columbia. Urheberrechtlich geschützt.

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192. The structure and relative stabilities of boric esters of 1,2- and 1,3-diols

Cited by 38 publications

References 0 publications

Boronolectins and fluorescent boronolectins: An examination of the detailed chemistry issues important for the design

Boronolectins and fluorescent boronolectins: An examination of the detailed chemistry issues important for the design

Quantum-chemical study on conformations of molecular complexes formed by 2-methyl-1,3,2-dioxaborinane with methylamine

Purification and Separation of Digoxin by Removal of Accompanying Glycosides as Phenylboronate Derivatives

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