Cycloaddition reactions of enoldiazo compounds
Qing-Qing Cheng1, Yongming Deng, Marianne Lankelma
1Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, USA. michael.doyle@utsa.edu.
Chemical Society Reviews
|July 21, 2017
Summary
Enoldiazo compounds are versatile reagents for cycloaddition reactions, enabling efficient synthesis of carbocycles and heterocycles. This review highlights their diverse reactivity and catalyst-controlled outcomes, inspiring future synthetic applications.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Catalysis
Background:
- Enoldiazo esters and amides are valuable synthons in organic chemistry.
- Cycloaddition reactions are crucial for constructing cyclic molecular frameworks.
- The development of novel synthetic methodologies is essential for advancing chemical synthesis.
Purpose of the Study:
- To provide a comprehensive review of cycloaddition reactions involving enoldiazo compounds.
- To highlight the versatility and synthetic utility of enoldiazo reagents.
- To discuss the role of different catalysts and their impact on reaction outcomes.
Main Methods:
- Review of existing literature on enoldiazo compound chemistry.
- Analysis of various cycloaddition reaction pathways ([2+n] and [3+n] cycloadditions).
- Discussion of catalyst-controlled chemodivergence, focusing on dirhodium(ii) and copper(i) catalysts.
Main Results:
- Enoldiazo compounds participate in diverse cycloaddition reactions, including those involving enol silyl ethers, metallo-enolcarbenes, and cyclopropenes.
- These reactions efficiently yield various carbocyclic and heterocyclic structures, as well as cyclopropane-fused systems.
- Catalyst choice (dirhodium(ii) vs. copper(i)) dictates reaction pathways and outcomes.
Conclusions:
- Enoldiazo compounds offer a versatile platform for constructing complex molecular architectures.
- Understanding catalyst-controlled reactivity is key to harnessing the full potential of these reagents.
- This review aims to stimulate further research and application of enoldiazo compounds in synthetic chemistry.
![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
01:16Cycloaddition Reactions: Overview
3.6K
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.
3.6K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
12.7K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
12.7K
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
4.8K
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
4.8K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.8K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.8K
01:14Dehydration of Aldols to Enals: Base-Catalyzed Aldol Condensation
7.3K
This lesson delves into the aldol condensation catalyzed by bases, where aldols undergo dehydration to enals. As shown in Figure 1, the β-hydroxy aldehyde formed in a base-catalyzed aldol addition reaction dehydrates on heating to yield an unsaturated carbonyl product, which is commonly referred to as an enal.
7.3K
01:26Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
4.2K
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.
4.2K