605-81-2Relevant articles and documents
Mechanism of the reductive cleavage reaction of permethylated methyl D-glycopyranosides
Lee, Chang Kiu,Kim, Eun Ju
, p. 223 - 229 (1999)
The mechanism of the reductive cleavage reaction of permethylated methyl D-glycopyranosides was investigated by measuring the rate of reaction. Glycosides employed were of α-Glc, β-Glc, α-Man, α-Gal, and β-Gal. Seven silanes were used to explore the reactivities of the reducing agents as well as to examine the stereoelectronic effects of the agents. Trimethylsilyl trifluoromethanesulfonate was employed as catalyst. In general, the rates of β anomers were about twice as fast as those of the α anomers. The rates of anomerization were about five to ten times lower than those of reduction. A cyclic oxonium ion has been proposed as a sole intermediate for the reductive cleavage of the α-glycoside linkage, but the attack of the reducing agent on both cyclic and acyclic forms as well as on the substrate-Lewis acid complex seems to be involved for the β anomer. Copyright (C) 1999 Elsevier Science Ltd.
A "traceless" Directing Group Enables Catalytic SN2 Glycosylation toward 1,2- cis-Glycopyranosides
Fu, Yue,Liu, Peng,Ma, Xu,Zhang, Liming,Zheng, Zhitong,Zhu, Xijun
, p. 11908 - 11913 (2021/08/20)
Generally applicable and stereoselective formation of 1,2-cis-glycopyranosidic linkage remains a long sought after yet unmet goal in carbohydrate chemistry. This work advances a strategy to this challenge via stereoinversion at the anomeric position of 1,2-trans glycosyl ester donors. This SN2 glycosylation is enabled under gold catalysis by an oxazole-based directing group optimally tethered to a leaving group and achieved under mild catalytic conditions, in mostly excellent yields, and with good to outstanding selectivities. The strategy is also applied to the synthesis of oligosaccharides.
Glucosylpolyphenols as Inhibitors of Aβ-Induced Fyn Kinase Activation and Tau Phosphorylation: Synthesis, Membrane Permeability, and Exploratory Target Assessment within the Scope of Type 2 Diabetes and Alzheimer's Disease
De Matos, Ana M.,Blázquez-Sánchez, M. Teresa,Bento-Oliveira, Andreia,De Almeida, Rodrigo F. M.,Nunes, Rafael,Lopes, Pedro E. M.,MacHuqueiro, Miguel,Cristóv?o, Joana S.,Gomes, Cláudio M.,Souza, Cleide S.,El Idrissi, Imane G.,Colabufo, Nicola A.,Diniz, Ana,Marcelo, Filipa,Oliveira, M. Concei??o,López, óscar,Fernandez-Bola?os, José G.,D?twyler, Philipp,Ernst, Beat,Ning, Ke,Garwood, Claire,Chen, Beining,Rauter, Amélia P.
, p. 11663 - 11690 (2020/11/26)
Despite the rapidly increasing number of patients suffering from type 2 diabetes, Alzheimer's disease, and diabetes-induced dementia, there are no disease-modifying therapies that are able to prevent or block disease progress. In this work, we investigate the potential of nature-inspired glucosylpolyphenols against relevant targets, including islet amyloid polypeptide, glucosidases, and cholinesterases. Moreover, with the premise of Fyn kinase as a paradigm-shifting target in Alzheimer's drug discovery, we explore glucosylpolyphenols as blockers of Aβ-induced Fyn kinase activation while looking into downstream effects leading to Tau hyperphosphorylation. Several compounds inhibit Aβ-induced Fyn kinase activation and decrease pTau levels at 10 μM concentration, particularly the per-O-methylated glucosylacetophloroglucinol and the 4-glucosylcatechol dibenzoate, the latter inhibiting also butyrylcholinesterase and β-glucosidase. Both compounds are nontoxic with ideal pharmacokinetic properties for further development. This work ultimately highlights the multitarget nature, fine structural tuning capacity, and valuable therapeutic significance of glucosylpolyphenols in the context of these metabolic and neurodegenerative disorders.
Establishment of Guidelines for the Control of Glycosylation Reactions and Intermediates by Quantitative Assessment of Reactivity
Chang, Chun-Wei,Wu, Chia-Hui,Lin, Mei-Huei,Liao, Pin-Hsuan,Chang, Chun-Chi,Chuang, Hsiao-Han,Lin, Su-Ching,Lam, Sarah,Verma, Ved Prakash,Hsu, Chao-Ping,Wang, Cheng-Chung
supporting information, p. 16775 - 16779 (2019/11/03)
Stereocontrolled chemical glycosylation remains a major challenge despite vast efforts reported over many decades and so far still mainly relies on trial and error. Now it is shown that the relative reactivity value (RRV) of thioglycosides is an indicator for revealing stereoselectivities according to four types of acceptors. Mechanistic studies show that the reaction is dominated by two distinct intermediates: glycosyl triflates and glycosyl halides from N-halosuccinimide (NXS)/TfOH. The formation of glycosyl halide is highly correlated with the production of α-glycoside. These findings enable glycosylation reactions to be foreseen by using RRVs as an α/β-selectivity indicator and guidelines and rules to be developed for stereocontrolled glycosylation.
Conversion of β-glycopyranoside to α-glycopyranoside by photo-activated radical reaction
Lai, Yu-Chen,Luo, Chin-Hung,Chou, Hsin-Chun,Yang, Cheng-Jhang,Lu, Le,Chen, Chien-Sheng
supporting information, p. 2474 - 2477 (2016/05/24)
By using carbon tetrachloride as the chloride radical and boron trifluoride etherate as the Lewis acid, the halogen-light-activated anomeric inversion of glycoside was achieved. This reaction is a novel guide to invert the glycosidic bond from a β-anomer to an α-anomer.
Structural analysis of novel kestose isomers isolated from sugar beet molasses
Shiomi, Norio,Abe, Tatsuya,Kikuchi, Hiroto,Aritsuka, Tsutomu,Takata, Yusuke,Fukushi, Eri,Fukushi, Yukiharu,Kawabata, Jun,Ueno, Keiji,Onodera, Shuichi
, p. 1 - 7 (2016/03/09)
Eight kestose isomers were isolated from sugar beet molasses by carbon-Celite column chromatography and HPLC. GC-FID and GC-MS analyses of methyl derivatives, MALD-TOF-MS measurements and NMR spectra were used to confirm the structural characteristics of the isomers. The 1H and 13C NMR signals of each isomer saccharide were assigned using COSY, E-HSQC, HSQC-TOCSY, HMBC and H2BC techniques. These kestose isomers were identified as α-D-fructofuranosyl-(2-> 2)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, α-D-fructofuranosyl-(2-> 3)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2-> 4)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, β-D-fructofuranosyl-(2- > 4)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, β-D-fructofuranosyl-(2- > 3)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, α-D-fructofuranosyl-(2- > 1)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2- > 6)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, and α-D-fructofuranosyl-(2- > 6)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside. The former five compounds are novel saccharides.
Visible light mediated activation and O-glycosylation of thioglycosides
Wever, Walter J.,Cinelli, Maris A.,Bowers, Albert A.
supporting information, p. 30 - 33 (2013/03/28)
Visible light catalysis allows the efficient construction of single electron transfer (SET) redox cycles that result in minimal formation of byproducts and proceed under exogenous control of a removable light source. The O-glycosylation of thioglycosides via visible light photoredox chemistry is reported. Mechanistic studies show that the reaction is fully light responsive and support a mechanism involving decomposition of an oxidatively generated sulfur radical cation and propagation via reduction of the thiol side product.
New method for regioselective glycosylation employing saccharide oxyanions
Matwiejuk, Martin,Thiem, Joachim
experimental part, p. 5860 - 5878 (2011/11/06)
As an alternative concept for glycosylation, the prior activation of acceptor hydroxy groups for selective glycosidic bond formation, was investigated to give complex oligosaccharides. Oxyanions obtained from partially protected saccharides were glycosylated by employing glycopyranosyl halides, and the regiochemical results were studied. Initially, partially methylated methyl-α-D-glucopyranosides were used as a model system to study the underlying mechanistic principles of base-promoted glycosylation. High regioselectivities and stereospecific glycosidic bond formations were achieved, and the scope of the methodology was extended with different perbenzylated glycosyl donors.
Anodic coupling reactions and the synthesis of C-glycosides
Xu, Guoxi,Moeller, Kevin D.
supporting information; scheme or table, p. 2590 - 2593 (2010/08/22)
A convenient, two-step procedure has been developed for converting sugar derivatives into C-glycosides containing a masked aldehyde functional group. The chemistry takes advantage of an anodic coupling reaction between an electron-rich olefin and an alcohol. The sequence works for the formation of both furanose and pyranose derivatives if less polarized vinyl sulfide derived radical cation intermediates are used. With more polarized enol ether derived radical cations, the cyclizations work best for the formation of furanose derivatives where the rate of five-membered ring formation precludes elimination reactions triggered by the radical cation.
Selective cleavage of methoxy protecting groups in carbohydrates
Boto, Alicia,Hernandez, Dacil,Hernandez, Rosendo,Suarez, Ernesto
, p. 1938 - 1948 (2007/10/03)
The selective cleavage of methoxy protecting groups next to hydroxy groups is achieved using a radical hydrogen abstraction reaction as the key step. Under the reaction conditions, the hydroxy group generates an alkoxyl radical that reacts with the sterically accessible adjacent methoxy group, which is transformed into an acetal. In the second step, the acetals are hydrolyzed to give alcohols or diols. A one-pot hydrogen abstraction-hydrolysis procedure was also developed. Good yields were usually achieved, and the mild conditions of this methodology were compatible with different functional groups and sensitive substrates such as carbohydrates.
