Scope
The synthetic utility can be extended to substitutions over butadiene bonds:
- Reaction in methanol and catalyst diisopropylethylamine
In the first step of this macrocyclization the thiol group in one end of 1,5-pentanedithiol reacts with the butadiene tail in 1 to the enone 2 in an allylic shift with a sulfone leaving group which reacts further with the other end in a conjugate addition reaction.
In one study the allylic shift was applied twice in a ring system:
In this reaction sequence a Jacobson epoxidation adds an epoxy group to a diene which serves as the leaving group in reaction with the pyrazole nucleophile. The second nucleophile is methylmagnesium bromide expulsing the pyrazole group.
An SN2' reaction should explain the outcome of the reaction of an aziridine carrying a methylene bromide group with methyllithium :
In this reaction one equivalent of acetylene is lost.
Examples of allylic shifts:
- Ferrier rearrangement
- Meyer–Schuster rearrangement
Read more about this topic: Allylic Rearrangement
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