Diels alder reaction, [2+4] addition reaction

1. els Alder Reaction or [2+4] cycloadditio
Department of Chemistry
and Chemical Sciences.
Central
University
of Jammu
Date: 23 December, 2021
Zuhaib Nasir Mughal 4040319

2. 2
Diels-Alder reaction
Otto Paul
diels
Kurt alder
1950

3. 1

4. 3π bonds 1π bond + 2σ bonds
[4+2] cycloaddition reaction

5. [2+2] cycloaddition
[4+4] cycloaddition
2

6. Even if we force 1,3-butadiene to react with itself, it will go for [4+2]Cyclo-addition but not

7. Why [2-4] addition
only?
Why not [2-2] addition?
Why not [4-4] addition?
🤔

8. In order the highest occupied molecular orbital of diene to put electron density
into lowest and occupied molecular orbital of dienophile, the relevant
overlapping orbital is must be in phase with one another.
Dienophole
Diene Diene Dienophole
HOMO
LUMO
The four pi electrons of diene which make it HOMO with one node and
two pi electrons in dienophile again with one node make it LUMO
Therefore, for its simple happened to be the case, that this in phase
overlap is possible with [4+2} but not work with other two. 3

9. Transition state have aromatic character
6π electrons
Also if we see benzene follows Huckle rule but Cyclo butadiene and cyclooctatetraene do
Like [6+4]. Cyclo addition.

10. 6π 4π

11. Special thanks to Dr. Princy Gupta (Ma’am)
Linkedin.com/ZuhaibNasir
Slideshare.net/ZuhaibNasir
4
5