Related Experiment Video
Updated: Jul 19, 2026
04:38
Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions
Published on: July 28, 2022
An unprecedented radical ring closure on a pyridine nitrogen
Myriem El-Qacemi1, Louis Ricard, Samir Z Zard
1Laboratoire de Synthèse Organique associé au CNRS, Département de Chimie, Ecole Polytechnique, F-91128 Palaiseau, France. elqacemi@dcso.polytechnique
Chemical Communications (Cambridge, England)
|October 24, 2006
Summary
Researchers discovered a novel radical ring-closure reaction targeting the pyridine nitrogen. This unprecedented chemical transformation occurs specifically when particular substituents are present on the pyridine ring.
Area of Science:
- Organic Chemistry
- Heterocyclic Chemistry
Background:
- Pyridine derivatives are crucial in pharmaceuticals and materials science.
- Controlling reactivity in pyridine systems is essential for synthetic advancements.
Purpose of the Study:
- To investigate novel reaction pathways for pyridine functionalization.
- To explore the mechanism of radical-mediated transformations involving pyridine.
Main Methods:
- Radical generation and trapping experiments.
- Spectroscopic analysis (NMR, Mass Spectrometry) to elucidate reaction products.
- Computational studies to understand the reaction mechanism.
Main Results:
- An unprecedented radical ring-closure reaction onto the pyridine nitrogen was observed.
- The reaction is dependent on specific substituents around the pyridine nucleus.
- The mechanism involves a radical intermediate attacking the pyridine nitrogen.
Conclusions:
- This study reveals a new synthetic route for complex pyridine derivatives.
- The findings expand the scope of radical chemistry in heterocyclic synthesis.
- The regioselectivity of the ring-closure offers potential for targeted molecular design.
More Related Videos
Related Concept Videos
02:26Base-Catalyzed Ring-Opening of Epoxides
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
02:24Acid-Catalyzed Ring-Opening of Epoxides
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
01:18Aromatic Hydrocarbon Anions: Structural Overview
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous overlap of p...
Due to the absence of continuous overlap of p...
01:33Radical Reactivity: Intramolecular vs Intermolecular
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak carbon–halogen...
00:47Radical Formation: Addition
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...