Organic reaction: Difference between revisions

Latest revision as of 16:33, 16 February 2025

Claisen Rearrangement[edit]

The Claisen rearrangement is a fundamental organic reaction that involves the [3,3]-sigmatropic rearrangement of an allyl vinyl ether to produce a _,_-unsaturated carbonyl compound. This reaction is named after the German chemist Ludwig Claisen, who first reported it in 1912.

Mechanism[edit]

The Claisen rearrangement is a concerted process, meaning that it occurs in a single step without the formation of intermediates. The reaction proceeds through a six-membered cyclic transition state, which is a hallmark of pericyclic reactions. The driving force for the rearrangement is the formation of a more stable carbonyl compound from the less stable allyl vinyl ether.

Variants[edit]

Several variants of the Claisen rearrangement exist, including:

The Johnson–Claisen rearrangement, which involves the use of an orthoester to generate the allyl vinyl ether in situ.
The Ireland–Claisen rearrangement, which uses a silyl ketene acetal as the starting material and is performed under basic conditions.
The Eschenmoser–Claisen rearrangement, which involves the rearrangement of allylic amines.

Applications[edit]

The Claisen rearrangement is widely used in organic synthesis to form carbon-carbon bonds and to introduce functional groups into molecules. It is particularly useful in the synthesis of natural products and complex organic molecules.

Related Pages[edit]

Template:Organic reactions

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-'''Organic reaction''' refers to the process in which organic compounds are transformed through chemical reactions. These reactions are fundamental to organic chemistry and are critical in the synthesis, modification, and degradation of organic molecules. Organic reactions are diverse and can involve the making or breaking of carbon-carbon bonds, carbon-hydrogen bonds, as well as the introduction or removal of various functional groups.
+== Claisen Rearrangement ==
-==Types of Organic Reactions==
+[[File:Claisen rearrangement scheme.svg|thumb|right|300px|Scheme of the Claisen rearrangement.]]
-Organic reactions can be classified into several types based on the mechanism by which they occur. Some of the major types include:
-* '''Addition Reactions''': In these reactions, two or more molecules combine to form a larger molecule. Examples include [[Hydrogenation]], where hydrogen is added to an unsaturated substrate, and [[Electrophilic addition]] to alkenes.
+The '''Claisen rearrangement''' is a fundamental [[organic reaction]] that involves the [3,3]-sigmatropic rearrangement of an allyl vinyl ether to produce a _,_-unsaturated carbonyl compound. This reaction is named after the German chemist [[Ludwig Claisen]], who first reported it in 1912.
-* '''Substitution Reactions''': These involve the replacement of one atom or group of atoms in a molecule with another. [[Nucleophilic substitution]] (SN1 and SN2) and [[Electrophilic substitution]] reactions are common examples.
-* '''Elimination Reactions''': These reactions result in the removal of atoms or groups from a molecule, leading to the formation of a double or triple bond. Examples include [[Dehydration of alcohols]] and [[Dehydrohalogenation]] of alkyl halides.
-* '''Rearrangement Reactions''': In these reactions, the structure of a molecule is rearranged to form a new isomer. The [[Beckmann rearrangement]] and [[Wagner-Meerwein rearrangement]] are notable examples.
-==Mechanisms of Organic Reactions==
+== Mechanism ==
-The mechanism of an organic reaction describes the step-by-step process by which reactants are converted into products. Understanding these mechanisms is crucial for predicting the outcome of reactions and for designing new synthetic pathways. Mechanisms involve various intermediates and transition states, and can be influenced by factors such as solvent, temperature, and the presence of catalysts.
-==Importance of Organic Reactions==
+The Claisen rearrangement is a concerted process, meaning that it occurs in a single step without the formation of intermediates. The reaction proceeds through a six-membered cyclic transition state, which is a hallmark of pericyclic reactions. The driving force for the rearrangement is the formation of a more stable carbonyl compound from the less stable allyl vinyl ether.
-Organic reactions are essential in the synthesis of a wide range of compounds that are important in pharmaceuticals, agrochemicals, materials science, and biochemistry. They enable the construction of complex molecular architectures from simpler precursors, allowing for the development of new drugs, polymers, and materials with novel properties.
-==Challenges in Organic Reactions==
+== Variants ==
-Despite their utility, organic reactions can pose challenges such as selectivity, yield, and environmental impact. Achieving high regioselectivity, stereoselectivity, and chemoselectivity is crucial for the synthesis of complex molecules. Additionally, efforts are being made to develop greener organic reactions that minimize the use of toxic reagents and solvents and reduce waste.
-==Future Directions==
+Several variants of the Claisen rearrangement exist, including:
-Advancements in organic chemistry continue to expand the scope and efficiency of organic reactions. Areas of active research include the development of new catalysts, photoredox chemistry, and the use of computational methods to predict reaction outcomes. These innovations aim to make organic synthesis more sustainable, efficient, and capable of producing more complex molecules.
-[[Category:Organic chemistry]]
+* The [[Johnson–Claisen rearrangement]], which involves the use of an orthoester to generate the allyl vinyl ether in situ.
-[[Category:Chemical reactions]]
+* The [[Ireland–Claisen rearrangement]], which uses a silyl ketene acetal as the starting material and is performed under basic conditions.
+* The [[Eschenmoser–Claisen rearrangement]], which involves the rearrangement of allylic amines.
-{{Chemistry-stub}}
+== Applications ==
+The Claisen rearrangement is widely used in [[organic synthesis]] to form carbon-carbon bonds and to introduce functional groups into molecules. It is particularly useful in the synthesis of natural products and complex organic molecules.
+== Related Pages ==
+* [[Pericyclic reaction]]
+* [[Sigmatropic reaction]]
+* [[Cope rearrangement]]
+{{Organic reactions}}
+[[Category:Organic reactions]]