Related Experiment Video
Updated: Apr 5, 2026
11:51
Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
12.5K
A [2 + 3] Reductive Cyclodimerization of Quinoline by SmI2
Ramesh Yella1, Hugo E Gottlieb1, Shmaryahu Hoz1
1Department of Chemistry, Bar-Ilan University , Ramat-Gan 5290002, Israel.
The Journal of Organic Chemistry
|August 13, 2015
Summary
Reducing pyridine derivatives is challenging due to rapid reoxidation. However, SmI2 reduction of quinoline triggers a rapid [2 + 3] cyclization, forming a unique bridged seven-membered ring in polycyclic systems.
Area of Science:
- Organic Chemistry
- Heterocyclic Chemistry
Background:
- Pyridine derivatives present challenges in reduction due to facile reoxidation.
- Aromaticity is readily regained by reduced pyridine products.
Purpose of the Study:
- To investigate the reduction of quinoline using samarium(II) iodide (SmI2).
- To explore the reaction products and mechanisms of quinoline reduction.
Main Methods:
- Reduction of quinoline using samarium(II) iodide (SmI2).
- Analysis of reaction products using spectroscopic and structural methods.
Main Results:
- The reduction of quinoline with SmI2 proceeds via an instantaneous [2 + 3] cyclization reaction.
- A bridged seven-membered ring is formed within a polycyclic system.
- The observed cyclization circumvents the typical reoxidation pathway.
Conclusions:
- Samarium(II) iodide is an effective reagent for the reductive cyclization of quinoline.
- This reaction provides a novel route to complex polycyclic structures containing bridged seven-membered rings.
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Related Concept Videos
01:17Oxidation of Phenols to Quinones
5.3K
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
5.3K
01:10Radical Chain-Growth Polymerization: Overview
3.7K
Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...
3.7K
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
4.2K
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
4.2K
01:18Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
2.8K
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
2.8K
01:16Cycloaddition Reactions: Overview
3.8K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
3.8K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
3.2K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
3.2K