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Related Concept Videos

Limitations of Friedel–Crafts Reactions01:26

Limitations of Friedel–Crafts Reactions

Several restrictions limit the use of Friedel–Crafts reactions. First, the halogen in the alkyl halide must be attached to an sp3-hybridized carbon for the Friedel–Crafts reactions to occur. Vinyl or aryl halides do not react since the carbocations formed are unstable under the reaction conditions. Second, Friedel–Crafts alkylation is susceptible to carbocation rearrangement, and the major products obtained have a rearranged carbon skeleton. In contrast, the acylium ion is stabilized by...
Electrophilic Aromatic Substitution: Friedel–Crafts Alkylation of Benzene01:17

Electrophilic Aromatic Substitution: Friedel–Crafts Alkylation of Benzene

Friedel–Crafts reactions were developed in 1877 by the French chemist Charles Friedel and the American chemist James Crafts. Friedel–Crafts alkylation refers to the replacement of an aromatic proton with an alkyl group via electrophilic aromatic substitution. A Lewis acid catalyst such as aluminum chloride reacts with an alkyl halide to form a carbocation. The resulting carbocation then reacts with the aromatic ring and undergoes a series of electron rearrangements before giving the final...
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene01:11

Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene

The Friedel–Crafts acylation reactions involve the addition of an acyl group to an aromatic ring. These reactions proceed via electrophilic aromatic substitution by employing an acyl chloride and a Lewis acid catalyst such as aluminum chloride to form aryl ketone.
Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia02:10

Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia

Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction01:16

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

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.
Diels–Alder Reaction: Characteristics of Dienes01:29

Diels–Alder Reaction: Characteristics of Dienes

The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...

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Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes
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Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

Published on: July 28, 2018

Natural friedelanes.

Wei-Guang Shan1, Li-Wen Zhang, Jia-Gui Xiang

  • 1College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, P. R. China.

Chemistry & Biodiversity
|August 14, 2013
PubMed
Summary
This summary is machine-generated.

This review details natural friedelane triterpenoids discovered from 1977 to 2011. It explores their origins, biological activities, and pharmacological properties, including key compounds like celastrol.

Keywords:
Biological activityFriedelanesTriterpenoids

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Area of Science:

  • Natural Product Chemistry
  • Pharmacology
  • Organic Chemistry

Background:

  • Friedelane triterpenoids are a class of natural products with diverse biological activities.
  • Research on these compounds has expanded significantly since 1977.
  • Understanding their occurrence and properties is crucial for drug discovery.

Purpose of the Study:

  • To comprehensively review the natural occurrence of friedelane triterpenoids.
  • To discuss the biogenesis of dimeric and rearranged friedelanes.
  • To compile and analyze the known biological and pharmacological activities of these compounds.

Main Methods:

  • Literature review of scientific publications from 1977 to March 2011.
  • Analysis of reported natural product isolation and characterization data.
  • Compilation of data on biological activities and pharmacological properties.

Main Results:

  • Extensive documentation of naturally occurring friedelane triterpenoids.
  • Insights into the biosynthetic pathways of complex friedelane structures.
  • Summary of pharmacological data for key compounds like celastrol and correolide.

Conclusions:

  • Friedelane triterpenoids represent a rich source of bioactive natural products.
  • Further research into their mechanisms of action and therapeutic potential is warranted.
  • This review serves as a valuable resource for chemists and pharmacologists.