Rearrangement reactions , Witting rearrangement reaction grovenstein rearrangement reaction , organic chemistry,

1. GOVT.J.YOGNANDAM CHATTISHGARH COLLEGE
RAIPUR (C.G.)PIN:492001
PREPARED BY :-
VIVEK YADU
GUIDED BY:-
DR. YAMINI THAKUR MAM
DR. GOVERDHAN VYAS SIR
SESSION 2022-
23
MASTER OF SCIENCE IN CHEMISTRY [1ST
SEMESTER]
PRESENTATION ON ORGANIC CHEMISTRY
[II]
TOPIC
“WITTING’S REARRANGEMENT REACTION” AND
“GROVENSTEIN-ZIMMERMAN REARRANGEMENT REACTION”

2. CONTENTS
• INTRODUCTION OF MOLECULAR REARRANGEMENT
• WITTING REARRANGEMENT REACTION
• MECHANISM OF WITTING’S REARRANGEMENT REACTION
• GROVENSTEIN-ZIMMERMAN REARRANGEMENT REACTION
• MECHANISM OF GROVENSTEIN REARRANGEMENT
REACTION
• REFERENCE

3. INTRODUCTION OF REARRANGEMENT
REACTIONS
• In a rearrangement reaction an atom or group moves from one atom to
another in the same molecule.
• Most of the migrations are form an atom to an adjacent one (called 1,2
shifts) but some are over longer distance.
The migrating group (W) may migrate with electron
pair(nucleophilic rearrangement) or without electron pair(electrophilic
rearrangement) or with one electron(free radical rearrangement) as the
case may be.
• The nucleophilic 1,2-Shifts are much more common than electrophilic or
free radical 1,2-shifts.

4. WITTING’S REARRANGEMENT REACTIONS
• In this reaction Ethers undergo [1,2]-sigmatropic rearrangement in
the presence of strong base such as amide ion or perylithium to give
more stable oxyanion.
Reaction:-

5. Mechanism
Example:-

6. Grovenstein-Zimmerman Rearrangement
Reaction
• This rearrangement reaction is reported by Zimmerman in 1967.
• In this rearrangement reaction 1,4 Diene rearranged vinyl
cyclopropane in the presence of light.
• Single unsaturated sp3 carbon required for this reaction.
• This reaction’s is found in another name called Di-𝝅 Methane
Rearrangement.
Reaction:-

7. Mechanism
A mechanism has been formulated that would involve formation of
diradical species 3 and 4, which however might not be real
intermediates. At least one substituent at C-3 is required in order to
stabilize the radical 4, and thereby facilitate the cleavage of the C-2/C-
3 bond.

8. Example:-
Refrence By:-
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