Some Concepts Of Claisen Rearrangement

1. CLAISEN
REARRANGEMENT

2. Introduction
• The Claisen Rearrangement is a powerful carbon-
carbon bond forming chemical reaction
discovered by RAINER LUDWIG CLAISEN. It is
the first Sigmatropic Rearrangement

3. When O-allyl ether of phenol is heated to about
200 degree centigrade in absence of any
catalyst, it rearrange to o-allyl phenol.

4. • This THERMAL REARRANGEMENT of
PHENOLIC ALLYL ETHERS is called
CLAISEN REARRANGEMENT .

5. It has been observed in this reaction:
1. The allyl group migrates almost invariable to the
ortho position unless the ortho position are blocked.
2. There is an inversion of the allyl group during the
rearrangement,i.e carbon atom of the allyl group which
get attached to the aromatic nucleus is not the one which
is attached to the oxygen atom of ether . For example-

6. 3. Rearrangement of mixtures of allyl phenyl
ethers do not give cross product, suggesting
that the rearrangement is truly intramolecular.
4. When both the ortho positions of phenyl
allyl ethers are blocked, the allyl group
migrates to para position on CLAISEN
REARRANGEMENT. For example-

7. Mechanism:-
• The cyclic mechanism, outlined below
accounts for the intramolecular
rearrangement of allyl ether to ortho allyl
phenol.

8. References
• 1. Modern Organic Chemistry by M.K. JAIN
and S.C. SHARMA
• 2. Advanced Organic Chemistry by Dr.
Jagdamba Singh and Dr. L.D.S Yadav
• 3. Wikipedia