Related Experiment Video
Updated: May 17, 2026
06:46
Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Selective cross-coupling of organic halides with allylic acetates
Lukiana L Anka-Lufford1, Michael R Prinsell, Daniel J Weix
1Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, USA.
The Journal of Organic Chemistry
|October 26, 2012
Summary
This study introduces a versatile method for coupling haloarenes with allylic acetates, showcasing broad substrate tolerance and applicability to secondary alkyl bromides and vinyl halides.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Developing efficient cross-coupling reactions is crucial for synthesizing complex organic molecules.
- Existing methods often face limitations in substrate scope and functional group tolerance.
Purpose of the Study:
- To present a general protocol for the palladium-catalyzed coupling of haloarenes with allylic acetates.
- To demonstrate the broad applicability and functional group tolerance of the developed method.
Main Methods:
- Palladium-catalyzed cross-coupling reaction.
- Utilized haloarenes and various allylic acetates as substrates.
- Employed modified conditions for secondary alkyl bromides and hindered ligands for vinyl halides.
Main Results:
- Successfully coupled a diverse range of haloarenes with allylic acetates.
- Demonstrated tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) functional groups.
- Extended the methodology to include secondary alkyl bromides and reactive vinyl halides.
Conclusions:
- The presented protocol offers a robust and versatile approach for allylation reactions.
- The method's functional group tolerance and broad scope facilitate the synthesis of complex organic structures.
Related Concept Videos
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
01:31Radical Substitution: Allylic Chlorination
Typically, when alkenes react with halogens at low temperatures, an addition reaction occurs. However, upon increasing the temperature or under reaction conditions that form radicals, providing a low but steady concentration of halogen radicals, allylic substitution reaction is favored. This is because allylic hydrogens are very reactive as the formed intermediate is resonance stabilized. For example, when propene is treated with chlorine in the gas phase at 400 °C, it undergoes allylic...
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
01:14α-Halogenation of Carboxylic Acid Derivatives: Overview
Unlike aldehydes and ketones, carboxylic acids do not readily participate in α halogenation reactions via enols or enolate intermediates. However, α-halogenated acids are obtained through other methods. One of the approaches is the Hell–Volhard–Zelinsky (HVZ) reaction, wherein the carboxylic acid is treated with halogen in the presence of PBr3. It involves the conversion of acid to acid halide, which exists in equilibrium with its enol form. The enol attacks the electrophilic halogen to produce...
01:27Radical Substitution: Allylic Bromination
In organic synthesis, the formation of products can be altered by changing the reaction conditions. For example, a dibromo addition product is formed when propene is treated with bromine at room temperature. In contrast, propene undergoes allylic substitution in non-polar solvents at high temperatures to give 3-bromopropene. In order to avoid the addition reaction, the bromine concentration must be kept as low as possible throughout the reaction. This can be achieved using N-bromosuccinimide...