18031-57-7Relevant academic research and scientific papers
Site-Selective Acylation of Pyranosides with Oligopeptide Catalysts
Seitz, Alexander,Wende, Raffael C.,Roesner, Emily,Niedek, Dominik,Topp, Christopher,Colgan, Avene C.,McGarrigle, Eoghan M.,Schreiner, Peter R.
, p. 3907 - 3922 (2021/03/09)
Herein, we report the oligopeptide-catalyzed site-selective acylation of partially protected monosaccharides. We identified catalysts that invert site-selectivity compared to N-methylimidazole, which was used to determine the intrinsic reactivity, for 4,6
In Situ Switching of Site-Selectivity with Light in the Acetylation of Sugars with Azopeptide Catalysts
Eckhardt, André K.,Erb, Frederik R.,Herold, Dominik,Kind, Jonas,Niedek, Dominik,Schreiner, Peter R.,Seitz, Alexander,Thiele, Christina M.,Topp, Christopher,Wende, Raffael C.
supporting information, (2020/02/04)
We present a novel concept for the in situ control of site-selectivity of catalytic acetylations of partially protected sugars using light as external stimulus and oligopeptide catalysts equipped with an azobenzene moiety. The isomerizable azobenzene-peptide backbone defines the size and shape of the catalytic pocket, while the π-methyl-l-histidine (Pmh) moiety transfers the electrophile. Photoisomerization of the E- to the Z-azobenzene catalyst (monitored via NMR) with an LED (λ = 365 nm) drastically changes the chemical environment around the catalytically active Pmh moiety, so that the light-induced change in the catalyst shape alters site-selectivity. As a proof of principle, we employed (4,6-O-benzylidene)methyl-α-d-pyranosides, which provide a change in regioselectivity from 2:1 (E) to 1:5 (Z) for the monoacetylated products at room temperature. The validity of this new catalyst-design concept is further demonstrated with the regioselective acetylation of the natural product quercetin. In situ irradiation NMR spectroscopy was used to quantify photostationary states under continuous irradiation with UV light.
DBN-Catalyzed Regioselective Acylation of Carbohydrates and Diols in Ethyl Acetate
Ren, Bo,Zhang, Mengyao,Xu, Shijie,Gan, Lu,Zhang, Li,Tang, Lin
supporting information, p. 4757 - 4762 (2019/07/31)
The 1,5-diazabicyclo[4.3.0]non-5-ene (DBN)-catalyzed regioselective acylation of carbohydrates and diols in ethyl acetate has been developed. The hydroxyl groups can be selectively acylated by the corresponding anhydride in EtOAc in the presence of a catalytic amount (as low as 0.1 equiv.) of DBN at room temperature to 40 °C. This method avoids metal catalysts and toxic solvents, which makes it comparatively green and mild, and it uses less organic base compared with other selective acylation methods. Mechanism studies indicated that DBN could catalyze the selective acylation of hydroxyl moieties through a dual H-bonding interaction.
Binding of the Bacterial Adhesin FimH to Its Natural, Multivalent High-Mannose Type Glycan Targets
Sauer, Maximilian M.,Jakob, Roman P.,Luber, Thomas,Canonica, Fabia,Navarra, Giulio,Ernst, Beat,Unverzagt, Carlo,Maier, Timm,Glockshuber, Rudi
, p. 936 - 944 (2019/01/11)
Multivalent carbohydrate-lectin interactions at host-pathogen interfaces play a crucial role in the establishment of infections. Although competitive antagonists that prevent pathogen adhesion are promising antimicrobial drugs, the molecular mechanisms underlying these complex adhesion processes are still poorly understood. Here, we characterize the interactions between the fimbrial adhesin FimH from uropathogenic Escherichia coli strains and its natural high-mannose type N-glycan binding epitopes on uroepithelial glycoproteins. Crystal structures and a detailed kinetic characterization of ligand-binding and dissociation revealed that the binding pocket of FimH evolved such that it recognizes the terminal α(1-2)-, α(1-3)-, and α(1-6)-linked mannosides of natural high-mannose type N-glycans with similar affinity. We demonstrate that the 2000-fold higher affinity of the domain-separated state of FimH compared to its domain-associated state is ligand-independent and consistent with a thermodynamic cycle in which ligand-binding shifts the association equilibrium between the FimH lectin and the FimH pilin domain. Moreover, we show that a single N-glycan can bind up to three molecules of FimH, albeit with negative cooperativity, so that a molar excess of accessible N-glycans over FimH on the cell surface favors monovalent FimH binding. Our data provide pivotal insights into the adhesion properties of uropathogenic Escherichia coli strains to their target receptors and a solid basis for the development of effective FimH antagonists.
Diisopropylethylamine-triggered, highly efficient, self-catalyzed regioselective acylation of carbohydrates and diols
Ren, Bo,Gan, Lu,Zhang, Li,Yan, Ningning,Dong, Hai
supporting information, p. 5591 - 5597 (2018/08/17)
A diisopropylethylamine (DIPEA)-triggered, self-catalyzed, regioselective acylation of carbohydrates and diols is presented. The hydroxyl groups can be acylated by the corresponding anhydride in MeCN in the presence of a catalytic amount of DIPEA. This method is comparatively green and mild as it uses less organic base compared with other selective acylation methods. Mechanistic studies indicate that DIPEA reacts with the anhydride to form a carboxylate ion, and then the carboxylate ion could catalyze the selective acylation through a dual H-bonding interaction.
Catalytic Site-Selective Acylation of Carbohydrates Directed by Cation-n Interaction
Xiao, Guozhi,Cintron-Rosado, Gabriel A.,Glazier, Daniel A.,Xi, Bao-Min,Liu, Can,Liu, Peng,Tang, Weiping
supporting information, p. 4346 - 4349 (2017/04/04)
Site-selective functionalization of hydroxyl groups in carbohydrates is one of the long-standing challenges in chemistry. Using a pair of chiral catalysts, we now can differentiate the most prevalent trans-1,2-diols in pyranoses systematically and predictably. Density functional theory (DFT) calculations indicate that the key determining factor for the selectivity is the presence or absence of a cation-n interaction between the cation in the acylated catalyst and an appropriate lone pair in the substrate. DFT calculations also provided a predictive model for site-selectivity and this model is validated by various substrates.
Monoacetylation of carbohydrate diols via transesterification with ethyl acetate
Liu, Xuyu,Becker, Bernd,Cooper, Matthew A.
, p. 679 - 683 (2014/05/06)
Monoacetylation of secondary diols in protected monosaccharides was achieved with ethyl acetate as acyl donor and sodium tert-butoxide as a base. The regioseletivity of the reaction varied depending on the substrate. This new method provides a simple, fast, and efficient method to access selectively acetylated carbohydrates that is compatible with acid-sensitive protecting groups. CSIRO 2014.
H-bonding activation in highly regioselective acetylation of diols
Zhou, Yixuan,Rahm, Martin,Wu, Bin,Zhang, Xiaoling,Ren, Bo,Dong, Hai
, p. 11618 - 11622 (2013/12/04)
H-bonding activation in the regioselective acetylation of vicinal and 1,3-diols is presented. Herein, the acetylation of the hydroxyl group with acetic anhydride can be activated by the formation of H-bonds between the hydroxyl group and anions. The reaction exhibits high regioselectivity when a catalytic amount of tetrabutylammonium acetate is employed. Mechanistic studies indicated that acetate anion forms dual H-bonding complexes with the diol, which facilitates the subsequent regioselective monoacetylation.
Chiral copper(II) complex-catalyzed reactions of partially protected carbohydrates
Allen, C. Liana,Miller, Scott J.
supporting information, p. 6178 - 6181 (2014/01/17)
Catalyst-controlled regioselective functionalization of partially protected saccharide molecules is a highly important yet under-developed area of carbohydrate chemistry. Such reactions allow for the reduction of protecting group manipulation steps required in syntheses involving sugars. Herein, an approach to these processes using enantiopure copper-bis(oxazoline) catalysts to control couplings of electrophiles to various partially protected sugars is reported. In a number of cases, divergent regioselectivity was observed as a function of the enantiomer of catalyst that is used.
Selective deprotection method of N -phenylcarbamoyl group
Akai, Shoji,Tanaka, Rika,Hoshi, Hidekazu,Sato, Ken-Ichi
, p. 8802 - 8808 (2013/09/24)
We report an improved method for the selective deprotection of the N-phenylcarbamoyl group, which yields the corresponding alcohol without affecting other protecting groups. Deprotection was performed using di-tert-butyl dicarbonate and tetra-n-butylammon
