18549-40-1Relevant articles and documents
Polymer-supported ferric chloride as a heterogeneous catalyst for chemoselective deprotection of acetonides
Chari, M. Adharvana,Syamasundar
, p. 708 - 710 (2005)
Acetonides undergo chemoselective deprotection to afford the corresponding 1,2-diols in excellent yields using polymer (PVP)-supported ferric chloride as a heterogeneous catalyst in acetonitrile-dichloromethane at room temperature.
Thermal and Lewis acid promoted intramolecular Diels-Alder reaction of furanose tethered 1,3,9-decatriene systems: A synthetic and computational investigation
Kalmode, Hanuman P.,Maity, Dilip K.,Bhate, Prakash M.
, p. 63445 - 63462 (2016)
The intramolecular Diels-Alder (IMDA) reaction of furanose tethered 1,3,9-decatrienes (4a-4r) was investigated under thermal conditions and in the presence of a Lewis acid. The stereoselectivity was determined by establishing the structures of adducts through single crystal X-ray diffraction and 1H NMR spectroscopy. It was found that contrary to expectations, the thermal IMDA reaction of (3E) and (3Z)-1,3,9-decatrienes proceeded with nearly equal rate and furnished IMDA adducts (6-25) with moderate stereoselectivity. In some cases, rearranged products (9, 12, 17 and 24) arising out of a 1,5-sigmatropic shift, cis-trans isomerization followed by IMDA reaction were formed. In contrast, a Lewis acid promoted IMDA reaction afforded only one adduct albeit in lower yields. Not surprisingly, cis-boat transition states were favored over trans-boat transition states. Experimental results were corroborated with transition state modeling of these reactions by applying density functional theory based electronic structure calculations.
Hydrogen isotopic profile in the characterization of sugars. Influence of the metabolic pathway
Zhang, Ben-li,Billault, Isabelle,Li, Xiaobao,Mabon, Francoise,Remaud, Gerald,Martin, Maryvonne L.
, p. 1574 - 1580 (2002)
The site-specific natural hydrogen isotope ratios of plant metabolites determined by 2H nuclear magnetic resonance (SNIF-NMR method) can provide powerful criteria for inferring mechanistic and environmental effects on biosynthetic pathways. This work examines the potential of isotopic profiles for the main constituents of carbohydrates, glucose and fructose, to distinguish different photosynthetic pathways. An appropriate analytical strategy, involving three suitable isotopic probes, has been elaborated with a view to measuring simultaneously, in conditions devoid of isotopic perturbations, all (or nearly all) of the carbon-bound hydrogen isotope ratios. It is shown that the type of photosynthetic metabolism, either C3 (sugar beet, orange, and grape), C4 (maize and sugar cane), or CAM (pineapple), and the physiological status of the precursor plant exert strong influences on the deuterium distribution in the sugar molecules. Consequently, this isotopic fingerprint may be a rich source of information for the comparison of mechanisms in metabolic pathways. In addition, it can provide complementary criteria to ethanol as a probe for the origin of sugars.
Chiron approach for the synthesis of (1S,2R,5R,7S)-2-hydroxy-exo-brevicomin
Gautam,Kumar, D. Naveen,Rao, B. Venkateswara
, p. 819 - 821 (2006)
(1S,2R,5R,7S)-2-Hydroxy-exo-brevicomin ent-1 was synthesized from 1,2;5,6-di-O-isopropylidene-d-glucose in seven steps. The key reaction in our synthesis is the formation of bicyclic ketal 7 under acid mediated acetal exchange of a 1,2-acetonide of d-glucose derivative 6.
Quantification of deuterium isotopomers of tree-ring cellulose using nuclear magnetic resonance
Betson, Tatiana R.,Augusti, Angela,Schleucher, Juergen
, p. 8406 - 8411 (2006)
Stable isotopes in tree rings are important tools for reconstruction of past climate. Deuterium (D) is of particular interest since it may contain climate signals and report on tree physiology. Measurements of the D/H ratio of tree-ring cellulose have proven difficult to interpret, presumably because the D/H ratio of the whole molecule blends the abundances of the seven D isotopomers of cellulose. Here we present a method to measure the abundance of the D isotopomers of tree-ring cellulose by nuclear magnetic resonance spectroscopy (NMR). The method transforms tree-ring cellulose into a glucose derivative that gives highly resolved, quantifiable deuterium NMR spectra. General guidelines for measurement of D isotopomers by NMR are described. The transformation was optimized for yield and did not alter the original D isotopomer abundances, thus, conserving the original signals recorded in wood cellulose. In the tree-ring samples tested, the abundances of D isotopomers varied by approximately ±10% (2% standard error). This large variability can only be caused by biochemistry processes and shows that more information is present in D isotopomer abundances, compared to the D/H ratio. Therefore, measurements of the D isotopomer distribution of tree rings may be used to obtain information on long-term adaptations to environmental changes and past climate change.
INTERACTION BETWEEN ACETONE AND SOME CARBOHYDRATE BENZENEBORONATES: SELECTIVE ACETONOLYSIS OF 2-PHENYL-1,3,2-DIOXABOROLANES
Griffiths, Chridtopher J.,Weigel, Helmut
, p. 17 - 22 (1980)
Treatment of D-glucitol 1,3:2,4:5,6-tris(benzeneboronate), D-mannitol 1,2:3,4:5,6-tris(benzeneboronate), and α-D-glucofuranose 1,2:3,5-bis(benzeneboronate) with acidified acetone, followed by chromatography using lyotropic solvents, gives 5,6-O-isopropylidene-D-glucitol, 1,2-O-isopropylidene-D-mannitol, and 1,2-O-isopropylidene-α-D-glucofuranose, respectively, in yields of 43-78percent.
A Warburg effect targeting vector designed to increase the uptake of compounds by cancer cells demonstrates glucose and hypoxia dependent uptake
Glenister, Alexandra,Simone, Michela I.,Hambley, Trevor W.
, (2019)
Glycoconjugation to target the Warburg effect provides the potential to enhance selective uptake of anticancer or imaging agents by cancer cells. A Warburg effect targeting group, rationally designed to facilitate uptake by glucose transporters and promote cellular accumulation due to phosphorylation by hexokinase (HK), has been synthesised. This targeting group, the C2 modified glucose analogue 2-(2-[2-(2-aminoethoxy)ethoxy]ethoxy)-D-glu-cose, has been conjugated to the fluorophore nitrobenzoxadiazole to evaluate its effect on uptake and accumulation in cancer cells. The targeting vector has demonstrated inhibition of glucose phosphorylation by HK, indicating its interaction with the enzyme and thereby confirming the potential to facilitate an intracellular trapping mechanism for compounds it is conjugated with. The cellular uptake of the fluorescent analogue is dependent on the glucose concentration and is so to a greater extent than is that of the widely used fluorescent glucose analogue, 2-NBDG. It also demonstrates selective uptake in the hypoxic regions of 3D spheroid tumour models whereas 2-NBDG is distributed primarily through the normoxic regions of the spheroid. The increased selectivity is consistent with the blocking of alternative uptake pathways.
A mild and convenient approach for selective acetonide cleavage involved in carbohydrate synthesis using PPA-SiO2
Nikam, Rahul R.,Gore, Kiran R.
, p. 63 - 74 (2020)
Here, we report a highly selective, efficient and rapid method for the selective cleavage of primary acetonide using silica supported polyphosphoric acid (PPA-SiO2) for various carbohydrate substrates. Corresponding diols were obtained in good to excellent yields within 30 min using PPA-SiO2. Overall, PPA-SiO2 was found to be a useful catalyst for selective acetonide cleavage in carbohydrate substrates which may expand its utility in organic synthesis.
Acetalation studies. Part IX. Reaction of sucrose and some related sugars with acetone in the presence of iodine; a novel cleavage-isopropylidenation method
Verhart, Cor G. J.,Caris, Brigitte M. G.,Zwanenburg, Binne,Chittenden, Gordon J. F.
, p. 348 - 352 (1992)
An efficient cleavage-isopropylidenation reaction of sucrose, catalyzed by iodine, is described.Related D-fructofuranosyl-containing oligosaccharides and their individual monosaccharide units were treated in a similar manner to yield isopropylidenated monosaccharide derivatives.The reaction conditions are particularly mild and selective.Some mechanistic aspects of the procedure are also discussed.
Synthesis and antimicrobial activity of (?)-cleistenolide and analogues
Benedekovi?, Goran,Popsavin, Mirjana,Radulovi?, Niko S.,Stojanovi?-Radi?, Zorica,Farkas, Sándor,Francuz, Jovana,Popsavin, Velimir
, (2020/12/07)
Using the “chiral pool” approach, two modified total syntheses of the biologically active δ-lactone cleistenolide (1) have been achieved starting from D-glucose. These approaches also enabled the preparation of novel analogues and derivatives of natural product 1. The applied strategy for the synthesis of 1 involves: the initial degradation of the chiral precursor for a single C-atom, C2-fragment chain extension using Z-selective Wittig reaction, and the final δ-lactonization. All tested cleistenolide analogues displayed antimicrobial activity against a panel of nine microbial strains, most of them superseding the activity of cleistenolide itself, and, in some cases, coming close in value to the observed minimal inhibitory concentrations of chloramphenicol. Increased lipophilicity of the derivatives and the non-sterically congested conjugated lactone moiety were a prerequisite for analogues with high inhibitory activity against S. aureus and, in general, Gram-positive bacteria.
