16.8 Sigmatropic Rearrangements
Course Menu
- 8.0 Naming Alkenes
- 8.1 Introduction to Alkene Addition Reactions
- 8.2 Hydrohalogenation
- 8.3 Hydration of Alkenes
- 8.4 Addition of Alcohols
- 8.5 Catalytic Hydrogenation
- 8.6 Halogenation of Alkenes and Halohydrin Formation
- 8.7 Epoxidation, Anti Dihydroxylation, and Syn Dihydroxylation
- 8.8 Predicting the Products of Alkene Addition Reactions
- 8.9 Oxidative Cleavage Ozonolysis and Permanganate Cleavage
- 13.1 Naming Ethers
- 13.2 Synthesis of Ethers
- 13.3 Reactions of Ethers
- 13.4 Nomenclature of Epoxides
- 13.5 Synthesis of Epoxides
- 13.6 Ring Opening of Epoxides
- 13.7 Nomenclature, Synthesis, and Reactions of Thiols
- 13.8 Nomenclature, Synthesis, and Reactions of Sulfides
- 13.9 Organic Synthesis with Ethers and Epoxides
- 14.1 Introduction to IR Spectroscopy
- 14.2a IR Spectra of Carbonyl Compounds
- 14.2b The Effect of Conjugation on the Carbonyl Stretching Frequency
- 14.3 Interpreting More IR Spectra
- 14.4 Introduction to Mass Spectrometry
- 14.5 Isotope Effects in Mass Spectrometry
- 14.6a Fragmentation Patterns of Alkanes, Alkenes, and Aromatic Compounds
- 14.6b Fragmentation Patterns of Alkyl Halides, Alcohols, and Amines
- 14.6c Fragmentation Patterns of Ketones and Aldehydes
- 15.1 Introduction to NMR
- 15.2 The Number of Signals in C 13 NMR
- 15.3 The Number of Signals in Proton NMR
- 15.4 Homotopic vs Enantiotopic vs Diastereotopic
- 15.5a The Chemical Shift in C 13 and Proton NMR
- 15.5b The Integration or Area Under a Signal in Proton NMR
- 15.5c The Splitting or Multiplicity in Proton NMR
- 15.6a Interpreting NMR Example 1
- 15.6b Interpreting NMR Example 2
- 15.6c Interpreting NMR Example 3
- 15.6d Structural Determination From All Spectra Example 4
- 15.6e Structural Determination From All Spectra Example 5
- 15.7 Complex Splitting
- 16.1 Introduction to Conjugated Systems and Heats of Hydrogenation
- 16.2a Pi Molecular Orbitals 1,3 Butadiene
- 16.2b Pi Molecular Orbitals the Allyl System
- 16.2c Pi Molecular Orbitals 1,3,5 Hexatriene
- 16.3 UV Vis Spectroscopy
- 16.4 Electrophilic Addition to Conjugated Dienes
- 16.5 Diels Alder Reactions
- 16.6 Cycloaddition Reactions
- 16.7 Electrocyclic Reactions
- 16.8 Sigmatropic Rearrangements
- 18.1 Electrophilic Aromatic Substitution
- 18.2 Friedel Crafts Alkylation and Acylation
- 18.3 Activating and Deactivating Groups | Ortho/Para vs Meta Directors
- 18.4 Catalytic Hydrogenation and the Birch Reduction
- 18.5 Side-Chain Reactions of Benzenes
- 18.6 Nucleophilic Aromatic Substitution
- 18.7 Retrosynthesis with Aromatic Compounds
- 19.1 Nomenclature of Ketones and Aldehydes
- 19.2 Synthesis of Ketones and Aldehydes
- 19.3 Introduction to Nucleophilic Addition Reactions of Ketones and Aldehydes
- 19.4a Formation of Hemiacetals and Acetals (Addition of Alcohols)
- 19.4b Cyclic Acetals as Protecting Groups
- 19.5 Formation of Imines and Enamines (Addition of Amines)
- 19.6 Reduction of Aldehydes and Ketones
- 19.7a Addition of Carbon Nucleophiles (Acetylide Ions, Grignard Reagents,etc.)
- 19.7b The Wittig Reaction
- 19.8 Baeyer Villiger Oxidation
- 19.9 Retrosynthesis with Aldehydes and Ketones
- 20.1 Naming Carboxylic Acids and Carboxylic Acid Derivatives
- 20.2 Nucleophilic Acyl Substitution
- 20.3 The Mechanisms of Nucleophilic Acyl Substitution
- 20.4 Reaction with Organometallic Reagents
- 20.5 Hydride Reduction Reactions
- 20.6 Synthesis and Reactions of Acid Halides
- 20.7 Synthesis and Reactions of Acid Anhydrides
- 20.8 Synthesis and Reactions of Esters
- 20.9 Properties, Synthesis, and Reactions of Carboxylic Acids
- 20.10 Synthesis and Reactions of Amides
- 20.11 Synthesis and Reactions of Nitriles
- 20.12 Retrosynthesis with Carboxylic Acids / Acid Derivatives
- 21.1 Acidity of the Alpha Hydrogen
- 21.2 Mechanisms of Alpha Substitution Reactions
- 21.3 Alpha Halogenation
- 21.4 Alpha Alkylation (including the Stork Reaction)
- 21.5 Aldol Reactions
- 21.6 Claisen Condensation Reactions
- 21.7 The Malonic Ester Synthesis and the Acetoacetic Ester Synthesis
- 21.8 Michael Reactions
- 21.9 The Robinson Annulation
- 21.10 Retrosynthesis with Enolates and Enols
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[1,5] Sigmatropic Rearrangement
-1 σ is broken and 1 new σ bond is formed
-Numerical notation indicates the number of atoms between new and old σ bonds
![[1,5] sigmatropic rearrangement](https://www.chadsprep.com/wp-content/uploads/2021/03/sigmatropic-rearrangement-01.png "[1,5] sigmatropic rearrangement")
Cope Rearrangement
-A [3,3] sigmatropic rearrangement
-All six atoms of the cyclic transition state are carbon atoms
-Equilbrium favors more substituted alkenes
Claisen Rearrangement
-A [3,3] sigmatropic rearrangement
-1 atom of the cyclic transition state is oxygen
- Occurs with allylic/vinyl or allylic/phenyl ethers
-Equilibrium often favors C=O formation
-allylic/phenyl ethers tautomerize to phenols
