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Chapter 12 Molecular Rearrangements. PRODUCER :张文勤. I Classification of Rearrangement Reactions ( ) II Nucleophilic Rearrangement ( ) 1 Wagner-Meerwein rearrangement ( ) 2 Pinacolic Rearrangement ( ) 3 α-ethandione Rearrangement ( ) 4 Beckmann Rearrangement ( )
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Chapter 12 Molecular Rearrangements PRODUCER:张文勤 I Classification of Rearrangement Reactions() II Nucleophilic Rearrangement () 1 Wagner-Meerwein rearrangement() 2 Pinacolic Rearrangement () 3 α-ethandione Rearrangement () 4 Beckmann Rearrangement () 5 Baeyer-Villiger Rearrangement () III Electrophilic Rearrangement() 1 favorskii Rearrangement 2 Stevens Rearrangement 3 Wittig Rearrangement 4 Fries Rearrangement IV Radical Rearrangement
I Classification of Rearrangement Reactions Molecular Rearrangements:it refers those reactions in which the carbon skeleton or the position of functional group changed.
Usually the rearrangement was classified by the electron property of the moving group, such as Nucleophilic rearrangement, Electrophilic rearrangement, Radical rearrangement, etc. Nucleophilic rearrangement
Electrophilic rearrangement Radical rearrangement
II Nucleophilic Rearrangement 1 Wagner-Meerwein rearrangement ( Carbon cation rearrangement )
Stable cation Stable cation
The stable cation formed superior Phenyl group move first
If NaOH was replaced by NaOMe or t-BuONa, α-hydroxycarboxyester will be produced Usually, ethyloxy anion acts as a reduction reagent.
4 Beckmann Rearrangement The group opposite to hydroxy will shift
Group moved as the following order: tertiary alkyl>aryl>H>secondary alkyl >primary alkyl>methyl
The cumene hydroperoxide rearrangement is quite resemble the Baeyer-Villiger Rearrangement
Important industrial reaction for manufacturing phenol and acetone
III Electrophilic Rearrangement Electrophilic rearrangement is not so common as nucleophilic rearrangement The transition state is:
For asymmetric cycloprapanone, the stable anion form dominantly
2 Stevens Rearrangement Structure maintaining