Organic chemistry features no more useful or strategically critical transformations than rearrangements. These reactions stand apart from simple substitutions or additions because they cause complete structural rearrangements within molecules through the migration of atoms or groups which frequently results in major changes to the carbon backbone or functional group arrangement. Understanding these intricate dances of atoms is crucial for designing complex synthetic routes, accessing valuable intermediates, and constructing intricate molecular architectures found in pharmaceuticals, agrochemicals, and advanced materials.
This page serves as your gateway to detailed insights into some of the most significant named rearrangement reactions. Each reaction is a testament to chemical ingenuity, offering unique pathways to build molecular complexity efficiently. Discover their mechanisms, scope, limitations, and modern applications through our curated resources.
Key Rearrangement Reactions
Baker-Venkataraman Rearrangement
A base-catalyzed intramolecular acyl transfer converting an ortho-acyloxy ketone into a 1,3-diketone, crucial for flavonoid synthesis.
Beckmann Rearrangement
The acid-catalyzed transformation of ketoximes into substituted amides (lactams for cyclic ketoximes), pivotal in nylon-6 production (from cyclohexanone oxime).
Brook Rearrangement
The base-induced 1,2-migration of a silyl group from carbon to oxygen in α-silyl alkoxides, generating silyl ethers and carbanions valuable for further chain elongation.
Carroll Rearrangement
A thermal [3,3]-sigmatropic rearrangement of allyl acetoacetates (or β-keto allyl esters) followed by decarboxylation, producing γ,δ-unsaturated ketones.
Claisen Rearrangement
A powerful thermal [3,3]-sigmatropic rearrangement of allyl vinyl ethers, yielding γ,δ-unsaturated carbonyl compounds, fundamental in forming C-C bonds with predictable stereochemistry.
Cope Rearrangement
A thermal [3,3]-sigmatropic rearrangement of 1,5-dienes, resulting in isomeric 1,5-dienes, a key method for ring expansion, contraction, and stereochemical control in synthesis.
Curtius Rearrangement
Thermal decomposition of acyl azides yields isocyanates, which can be hydrolyzed to amines or trapped with nucleophiles.
Demjanov Rearrangement
Treatment of primary aliphatic amines or cycloalkylmethylamines with nitrous acid leads to ring expansion or rearrangement products via diazonium intermediates.
Favorskii Rearrangement
Base-catalyzed rearrangement of α-halo ketones (or cyclic α,α'-dihalo ketones) forms carboxylic acids or esters, often involving a cyclopropanone intermediate.
Fries Rearrangement
Lewis acid-catalyzed rearrangement of phenolic esters yields ortho- and/or para-hydroxy aryl ketones via acyl migration.
Hofmann Rearrangement
Treatment of primary carboxamides with bromine and base generates isocyanates via hypobromite intermediates, leading to amines after hydrolysis.
Lossen Rearrangement
Base-induced rearrangement of activated hydroxamic acids (e.g., O-acyl derivatives) produces isocyanates, which are subsequently trapped to form amines, carbamates, or ureas.
Ireland-Claisen Rearrangement
A [3,3]-sigmatropic rearrangement of allylic esters via silyl ketene acetals to furnish γ,δ-unsaturated carboxylic acids with strong stereochemical control.
Eschenmoser-Claisen Rearrangement
A Claisen-type [3,3]-sigmatropic rearrangement of allylic alcohols, via ketene N,O-acetal intermediates, to give γ,δ-unsaturated amides.
Meyer-Schuster Rearrangement
Acid‑ or metal‑catalyzed isomerization of secondary or tertiary propargylic alcohols into α,β‑unsaturated carbonyl compounds via an allenol intermediate.
Rupe Rearrangement
Acid‑catalyzed conversion of tertiary propargylic alcohols bearing a terminal alkyne into α,β‑unsaturated methyl ketones through an enyne intermediate.
Mislow-Evans Rearrangement
A reversible, stereospecific [2,3]‑sigmatropic rearrangement of allylic sulfoxides to allylic sulfenate esters, which upon thiophilic trapping yields allylic alcohols with transfer of chirality from sulfur to carbon.
Neber Rearrangement
The base-induced rearrangement of oxime O-sulfonates to 2H-azirines or, after hydrolysis, α-aminoketones.
Overman Rearrangement
A [3,3]-sigmatropic rearrangement that converts allylic alcohols into allylic amines via a trichloroacetimidate intermediate, with a clean 1,3-transposition of the alkenyl moiety.
Payne Rearrangement
The base-induced, reversible isomerization of a 2,3-epoxy alcohol to an isomeric 1,2-epoxy alcohol with inversion of configuration at the migration terminus.
Polonovski Reaction
The transformation of a tertiary amine N-oxide into an iminium ion intermediate upon treatment with an acylating agent (e.g., acetic anhydride), which can lead to products such as N-acyl secondary amines and aldehydes.
Polonovski-Potier Rearrangement
A modification of the Polonovski reaction using trifluoroacetic anhydride (TFAA) as the activating agent, which stabilizes the iminium ion intermediate, allowing it to be isolated or trapped by nucleophiles.
Pummerer Rearrangement
The acid‑mediated (typically using acetic anhydride) conversion of a sulfoxide bearing an α‑hydrogen into an α‑acyloxy sulfide via a thionium ion intermediate, with subsequent nucleophilic trapping.
Schmidt Rearrangement
The acid‑catalyzed reaction of carboxylic acids, ketones, or aldehydes with hydrazoic acid to give amines (via isocyanates), amides, or nitriles, respectively, through a 1,2‑shift of a group to an electron‑deficient nitrogen center.
Wagner-Meerwein Rearrangement
A classic carbocationic rearrangement involving the 1,2‑shift of an alkyl or aryl group to an adjacent carbocationic center, leading to a more stable carbocation or alkene with concomitant skeletal reorganization.
Wolff Rearrangement
The photochemical, thermal, or transition‑metal‑catalyzed conversion of an α‑diazoketone to a ketene, which is then trapped by water, alcohols, or amines to afford carboxylic acids, esters, or amides, respectively.
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