ZnI2-Directed Stereocontrolled α-Glucosylation
Siai Zhou1, Xuemei Zhong1, Aoxin Guo2
1School of Pharmaceutical Sciences-Shenzhen, Sun Yat-sen University, Shenzhen 518107, China.
Organic Letters
|August 19, 2021
Summary
A new glucosylation method uses zinc iodide (ZnI2) to create 1,2-cis-O-glycosidic linkages. This strategy enables the modular synthesis of diverse alpha-glucans, including branched structures.
Area of Science:
- Carbohydrate Chemistry
- Organic Synthesis
- Glycosylation Reactions
Background:
- Stereoselective synthesis of O-glycosidic linkages is crucial for carbohydrate chemistry.
- Developing efficient and mild methods for alpha-glucan synthesis remains a challenge.
Purpose of the Study:
- To develop a novel, highly stereoselective glucosylation strategy.
- To enable the modular synthesis of alpha-glucans with diverse structures.
Main Methods:
- Utilized zinc iodide (ZnI2) as a mild Lewis acid catalyst.
- Employed 4,6-O-tethered glucosyl donors and various acceptors.
- Investigated the stereoselectivity of the O-glycosidic bond formation.
Main Results:
- Achieved highly stereoselective construction of 1,2-cis-O-glycosidic linkages.
- Demonstrated the versatility of the alpha-glucosylation strategy with complex alcohols.
- Successfully synthesized various alpha-glucans with linear and branched backbones.
Conclusions:
- ZnI2-mediated glucosylation offers an efficient route to alpha-glucans.
- The developed method allows for modular synthesis of complex carbohydrate structures.
- This approach provides a valuable tool for accessing diverse alpha-glucan architectures.
Related Concept Videos
02:23SN2 Reaction: Stereochemistry
10.1K
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
10.1K
02:15SN1 Reaction: Stereochemistry
9.2K
This lesson provides an in-depth discussion of the stereochemical outcomes in an SN1 reaction.
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
9.2K
01:14Alkylation of β-Diester Enolates: Malonic Ester Synthesis
3.6K
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
3.6K
01:07Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis
3.7K
Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an...
3.7K
00:56Crossed Aldol Reaction Using Strong Bases: Directed Aldol Reaction
2.3K
The reaction between two different carbonyl compounds comprising α hydrogen in the presence of a strong base like lithium diisopropylamide (LDA) to form a crossed aldol product is known as a directed aldol reaction. The directed aldol reaction is depicted in Figure 1.
2.3K
01:24Oligosaccharide Assembly
3.1K
Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...
Multiple sugar molecules that may or may...
3.1K