Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Alkylation of β-Diester Enolates: Malonic Ester Synthesis

Alkylation of β-Diester Enolates: Malonic Ester Synthesis

Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.

Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview

Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview

In the presence of an aqueous base and a halogen, primary amides can lose the carbonyl (as carbon dioxide) and undergo rearrangement to form primary amines. This reaction, called the Hofmann rearrangement, can produce primary amines (aryl and alkyl) in high yields without contamination by secondary and tertiary amines.

Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Mechanism

Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Mechanism

Carboxylic acids react with alcohols to yield esters via an acid-catalyzed condensation reaction called Fischer esterification. This is a nucleophilic acyl substitution reaction that proceeds via a tetrahedral intermediate, where a water molecule is eliminated as the leaving group.

Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis

Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis

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 alkylated β-keto acid.

Regioselective Formation of Enolates

Regioselective Formation of Enolates

As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are more stable. But the energy required to form kinetic enolates is less.

Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism

Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism

The Hofmann and Curtius rearrangement reactions can be applied to synthesize primary amines from carboxylic acid derivatives such as amides and acyl azides. In the Hofmann rearrangement, a primary amide undergoes deprotonation in the presence of a base, followed by halogenation to generate an N-haloamide. A second proton abstraction produces a stabilized anionic species, which rearranges to an isocyanate intermediate via an alkyl group migration from the carbonyl carbon to the neighboring...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Synthesis and Immunological Evaluation of Pel-Derived Glycoconjugate Vaccine Candidates against <i>Pseudomonas aeruginosa</i>.

JACS Au·2026

Same author

Oseltamivir aziridines are potent influenza neuraminidase inhibitors and imaging agents.

Proceedings of the National Academy of Sciences of the United States of America·2026

Same author

Fully protected pyrophosphates <i>via</i> phosphorobromidates for the synthesis of biopolymers.

Chemical science·2026

Same author

Modular Synthesis of Nucleoside Diphosphate Sugar Analogues Using Chlorosulfonyl Isocyanate and Dichlorophosphoryl Isocyanate.

Organic letters·2026

Same author

Synthesis of Adenosine Diphosphate Ribose Histidine.

Organic letters·2026

Same author

How electronic and steric effects in acceptor alcohols shape S<sub>N</sub>1- and S<sub>N</sub>2-type glycosylation reactions.

Chemical science·2025

Search research articles

Related Experiment Video

Updated: Jun 21, 2026

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

Published on: January 15, 2018

Equatorial anomeric triflates from mannuronic acid esters.

Marthe T C Walvoort¹, Gerrit Lodder, Jaroslaw Mazurek

¹Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.

Journal of the American Chemical Society

|August 12, 2009

Summary

Mannuronic acid triflates form an unexpected equatorial triflate intermediate, stabilized by carboxylate groups. This conformation explains the high beta-selectivity observed in glycosylation reactions involving mannuronates.

More Related Videos

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Published on: July 26, 2018

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Published on: January 19, 2016

Related Experiment Videos

Last Updated: Jun 21, 2026

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

Published on: January 15, 2018

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Published on: July 26, 2018

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Published on: January 19, 2016

Area of Science:

Carbohydrate Chemistry
Organic Chemistry
Stereochemistry

Background:

The anomeric effect typically favors axial substituents at the anomeric center in pyranose rings.
Understanding reaction mechanisms and stereochemical outcomes in glycosylation is crucial for carbohydrate synthesis.

Purpose of the Study:

To investigate the conformational preferences of alpha-anomeric triflates derived from mannuronic acid esters.
To elucidate the factors contributing to the observed beta-selectivity in mannuronate glycosylations.

Main Methods:

Computational modeling to analyze conformational energies.
Analysis of stereochemical outcomes in glycosylation reactions.

Main Results:

Activation of mannuronic acid esters yields a mixture of alpha-anomeric triflates, with preferential formation of the equatorial triflate in a (1)C(4) chair conformation.
This equatorial conformation is stabilized by the C-5 carboxylate group, counteracting the typical anomeric effect.
The (1)C(4) chair conformation approximates a (3)H(4) half-chair oxacarbenium ion, facilitating glycosylation.

Conclusions:

The preferential formation of the equatorial triflate intermediate is a key factor in the high beta-selectivity of mannuronate glycosylations.
Cooperative effects of the triflate counterion and stereoelectronic factors stabilize the oxacarbenium ion transition state, leading to the 1,2-cis product.