Remote Electronic Effects by Ether Protecting Groups Fine-Tune Glycosyl Donor Reactivity

2016 ◽  
Vol 81 (12) ◽  
pp. 4988-5006 ◽  
Author(s):  
Mads Heuckendorff ◽  
Lulu Teressa Poulsen ◽  
Henrik H. Jensen
Keyword(s):  
Protecting Groups ◽  
Electronic Effects ◽  
Glycosyl Donor ◽  
Fine Tune

C-Glycosylation of Oxygenated Naphthols with 3-Dimethylamino-2,3,6-trideoxy-L-arabino-hexopyranose and 3-Azido-2,3,6-trideoxy-D-arabino-hexopyranose

2003 ◽  
Vol 56 (8) ◽  
pp. 787 ◽  
Author(s):  
Margaret A. Brimble ◽  
Roger M. Davey ◽  
Malcolm D. McLeod ◽  
Maureen Murphy
Keyword(s):  
Lewis Acid ◽  
Boron Trifluoride ◽  
Electronic Effects ◽  
Effective Coupling ◽  
Boron Trifluoride Diethyl Etherate ◽  
Glycosyl Donor ◽  
Aryl Glycosides ◽  
Coupling Partner ◽  
Fine Tune ◽  
Glycosyl Donors

In connection with studies directed towards the synthesis of the pyranonaphthoquinone antibiotic medermycin, C-aryl glycosides were prepared by C-glycosylation of naphthols with glycosyl donors. Boron trifluoride diethyl etherate proved to be a suitable Lewis acid to promote the C-glycosylation, and use of the azido glycosyl donor proved more successful than using the dimethylamino glycosyl donor. 5-Hydroxy-1,4-dimethoxynaphthalene underwent facile C-glycosylation with two particular glycosyl donors, whereas 3-bromo-5-hydroxy-1,4-dimethoxynaphthalene was not an effective coupling partner with the same glycosyl donors. These studies indicate that subtle steric and electronic effects need to be considered in order to fine-tune C-glycosylations when using highly functionalized glycosyl donors.

scholarly journals A One-Pot Approach to Novel Pyridazine C-Nucleosides

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2341
Author(s):  
Flavio Cermola ◽  
Serena Vella ◽  
Marina DellaGreca ◽  
Angela Tuzi ◽  
Maria Rosaria Iesce
Keyword(s):  
Organic Chemistry ◽  
Research Field ◽  
Modified Nucleosides ◽  
Protecting Groups ◽  
Coupling Reactions ◽  
One Pot ◽  
Pharmacological Interest ◽  
Classical Methodology ◽  
Glycosyl Donor ◽  
Neutral Conditions

The synthesis of glycosides and modified nucleosides represents a wide research field in organic chemistry. The classical methodology is based on coupling reactions between a glycosyl donor and an acceptor. An alternative strategy for new C-nucleosides is used in this approach, which consists of modifying a pre-existent furyl aglycone. This approach is applied to obtain novel pyridazine C-nucleosides starting with 2- and 3-(ribofuranosyl)furans. It is based on singlet oxygen [4+2] cycloaddition followed by reduction and hydrazine cyclization under neutral conditions. The mild three-step one-pot procedure leads stereoselectively to novel pyridazine C-nucleosides of pharmacological interest. The use of acetyls as protecting groups provides an elegant direct route to a deprotected new pyridazine C-nucleoside.

scholarly journals Steric and Electronic Effects of Ligand Substitution on Redox-Active Fe4S4-Based Coordination Polymers

2021 ◽  
Author(s):  
Omar Salinas ◽  
Jiaze Xie ◽  
Robert J. Papoular ◽  
Noah E. Horwitz ◽  
Erik Elkaim ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Photoelectron Spectroscopy ◽  
Electronic Effects ◽  
Iron Sulfur Clusters ◽  
Iron Sulfur ◽  
Redox Active ◽  
Metal Organic ◽  
Uv Visible ◽  
And Function ◽  
Fine Tune

<div>One of the notable advantages of molecular materials is the ability to precisely tune structure, properties, and function via molecular substitutions. While many studies have demonstrated this principle with classic carboxylate‐based coordination polymers, there are comparatively fewer examples where systematic changes to sulfur‐based coordination polymers have been investigated. Here we present such a study on 1D coordination chains of redox‐active</div><div>iron-sulfur clusters linked by methylated 1,4‐benzene‐dithiolates. A series of new iron-sulfur based coordination polymers were synthesized with either 2,5‐dimethyl‐1,4‐benzenedithiol (DMBDT) or 2,3,5,6‐tetramethyl‐1,4‐benzenedithiol. The structures of these compounds have been characterized based on synchrotron Xray</div><div>powder diffraction while their chemical and physical properties have been characterized by techniques including X‐ray photoelectron spectroscopy, cyclic voltammetry and UV–visible spectroscopy. Methylation results in the general trend of increasing electron‐richness in the series, but the tetramethyl version exhibits unexpected properties arising from steric constraints. All these results highlight how substitutions on organic linkers can modulate electronic factors to fine‐tune the electronic structures of metal‐organic materials.</div>

Glycosynthases: Mutant Glycosidases for Glycoside Synthesis

2002 ◽  
Vol 55 (2) ◽  
pp. 3 ◽  
Author(s):  
S. J. Williams ◽  
S. G. Withers
Keyword(s):  
Substrate Specificity ◽  
Product Formation ◽  
Protecting Groups ◽  
Rapid Screening ◽  
Widespread Application ◽  
Glycoside Synthesis ◽  
General Methodology ◽  
Glycosyl Donor ◽  
Substrate Variation ◽  
Catalytic Power

Glycosynthases are engineered mutant glycosidases that catalyse the formation of a glycosidic bond from a glycosyl donor and an acceptor alcohol. They are constructed by mutation of the enzymic nucleophile of a retaining glycosidase to a small non-nucleophilic residue. To date, five glycosynthases have been reported capable of synthesizing a range of β-glycosidic linkages. Methods to integrate protecting groups into glycosynthase-mediated glycosylations have been developed that broaden their applicability and enable finer control over product formation. Mutagenesis studies have improved the catalytic power of the original Abg glycosynthase, and a general methodology has been developed that allows the rapid screening of libraries of mutant glycosynthases for catalysts with improved activity. A method for determining aglycon substrate specificity has been developed to define the limits of substrate variation tolerated by a parent glycosidase and thence the derived glycosynthase. Together, these developments portend a bright future for the discovery of new glycosynthases and their widespread application as catalysts to assist in the rapid and efficient assembly of complex glycoconjugates.

scholarly journals Gold-catalyzed glycosidation for the synthesis of trisaccharides by applying the armed–disarmed strategy

2013 ◽  
Vol 9 ◽  
pp. 2147-2155 ◽  
Author(s):  
Abhijeet K Kayastha ◽  
Srinivas Hotha
Keyword(s):  
Reaction Temperature ◽  
Acidic Medium ◽  
Gold Catalysis ◽  
Protecting Groups ◽  
Benzyl Ethers ◽  
Glycosyl Donor ◽  
Leaving Groups

The synthesis of oligosaccharides is still a challenging task as there is no universal glycosyl donor for the synthesis of all oligosaccharides. The gold catalysis for glycosidation reactions, in which alkynylated glycosides are used, has emerged as one of the versatile options in this regard. A cleavage of the interglycosidic bond that was thought to be due to the higher reaction temperature and the acidic medium was observed during the synthesis of trisaccharides. In addition, a very little percentage of deprotection of benzyl protecting groups at the C-6 position was observed and no deprotection of benzyl ethers in aliphatic molecules was noticed. In order to overcome this fact, a collection of leaving groups that contain an alkynyl moiety were screened. It was found that 1-ethynylcyclohexanyl (Ech) glycosides are suitable for carrying out the glycosidation at 25 °C in the presence of 5 mol % each of AuCl3 and AgSbF6. Subsequently, Ech-glycosides were observed to be suitable for the synthesis of trisaccharides under gold catalysis conditions.

scholarly journals Steric and Electronic Effects of Ligand Substitution on Redox-Active Fe4S4-Based Coordination Polymers

2021 ◽  
Author(s):  
Omar Salinas ◽  
Jiaze Xie ◽  
Robert J. Papoular ◽  
Noah E. Horwitz ◽  
Erik Elkaim ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Photoelectron Spectroscopy ◽  
Electronic Effects ◽  
Iron Sulfur Clusters ◽  
Iron Sulfur ◽  
Redox Active ◽  
Metal Organic ◽  
Uv Visible ◽  
And Function ◽  
Fine Tune

<div>One of the notable advantages of molecular materials is the ability to precisely tune structure, properties, and function via molecular substitutions. While many studies have demonstrated this principle with classic carboxylate‐based coordination polymers, there are comparatively fewer examples where systematic changes to sulfur‐based coordination polymers have been investigated. Here we present such a study on 1D coordination chains of redox‐active</div><div>iron-sulfur clusters linked by methylated 1,4‐benzene‐dithiolates. A series of new iron-sulfur based coordination polymers were synthesized with either 2,5‐dimethyl‐1,4‐benzenedithiol (DMBDT) or 2,3,5,6‐tetramethyl‐1,4‐benzenedithiol. The structures of these compounds have been characterized based on synchrotron Xray</div><div>powder diffraction while their chemical and physical properties have been characterized by techniques including X‐ray photoelectron spectroscopy, cyclic voltammetry and UV–visible spectroscopy. Methylation results in the general trend of increasing electron‐richness in the series, but the tetramethyl version exhibits unexpected properties arising from steric constraints. All these results highlight how substitutions on organic linkers can modulate electronic factors to fine‐tune the electronic structures of metal‐organic materials.</div>

scholarly journals Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

2017 ◽  
Vol 13 ◽  
pp. 1239-1279 ◽  
Author(s):  
A Michael Downey ◽  
Michal Hocek
Keyword(s):  
Biological Process ◽  
Protecting Groups ◽  
Protecting Group ◽  
Research Groups ◽  
Selective Activation ◽  
Chemical Laboratory ◽  
Differential Reactivity ◽  
Glycosyl Donor ◽  
Anomeric Center

Glycosylation is an immensely important biological process and one that is highly controlled and very efficient in nature. However, in a chemical laboratory the process is much more challenging and usually requires the extensive use of protecting groups to squelch reactivity at undesired reactive moieties. Nonetheless, by taking advantage of the differential reactivity of the anomeric center, a selective activation at this position is possible. As a result, protecting group-free strategies to effect glycosylations are available thanks to the tremendous efforts of many research groups. In this review, we showcase the methods available for the selective activation of the anomeric center on the glycosyl donor and the mechanisms by which the glycosylation reactions take place to illustrate the power these techniques.

Quantifying Electronic Effects of Common Carbohydrate Protecting Groups in a Piperidine Model System

2010 ◽  
Vol 16 (47) ◽  
pp. 13982-13994 ◽  
Author(s):  
Mads Heuckendorff ◽  
Christian M. Pedersen ◽  
Mikael Bols
Keyword(s):  
Model System ◽  
Protecting Groups ◽  
Electronic Effects

Synthesis of the Nephritogenoside Trisaccharide Unit Using Phenyl 1-Thioglycopyranoside Sulfoxides as a Glycosyl Donor

1993 ◽  
Vol 48 (8) ◽  
pp. 1143-1145 ◽  
Author(s):  
Yali Wang ◽  
Hong Zhang ◽  
Wolfgang Voelter
Keyword(s):  
Protecting Groups ◽  
Coupling Process ◽  
Mild Conditions ◽  
Glycosyl Donor ◽  
Glycosyl Donors

The nephritogenoside trisaccharide unit was synthesized under mild conditions using phenyl 1-thioglycopyranoside sulfoxides as glycosyl donors. In the coupling process neither thiophenyl nor trityl protecting groups are cleaved from the carbohydrate moieties demonstrating the utility of this method also for oligosaccharide block syntheses.

scholarly journals The Synthesis of Blood Group Antigenic A Trisaccharide and Its Biotinylated Derivative

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5887
Author(s):  
Ekaterina D. Kazakova ◽  
Dmitry V. Yashunsky ◽  
Nikolay E. Nifantiev
Keyword(s):  
Blood Cell ◽  
Blood Group ◽  
Protecting Groups ◽  
Blood Group Antigens ◽  
Cell Recognition ◽  
Terminal Residue ◽  
Biochemical Studies ◽  
Glycosyl Donor

Blood group antigenic A trisaccharide represents the terminal residue of all A blood group antigens and plays a key role in blood cell recognition and blood group compatibility. Herein, we describe the synthesis of the spacered A trisaccharide by means of an assembly scheme that employs in its most complex step the recently proposed glycosyl donor of the 2-azido-2-deoxy-selenogalactoside type, bearing stereocontrolling 3-O-benzoyl and 4,6-O-(di-tert-butylsilylene)-protecting groups. Its application provided efficient and stereoselective formation of the required α-glycosylation product, which was then deprotected and subjected to spacer biotinylation to give both target products, which are in demand for biochemical studies.

Sign in / Sign up

Export Citation Format

Share Document