1
Diels – Alder Reaction
1,4-CycloAddition Reaction of Dienes
Solomons and Fryhle: 13.11
2
What is a Diels-Alder 1,4 Cycloaddition Reaction?
3
What’s Going With Respect to a Diels-Alder 1,4 Cycloaddition Reaction?
XX+
Diene
S-cis
Dieneophile Diels Alder Adduct
Cyclohexene derivative
3 π bonds convert into one π bond + two σ bonds
Note: σ bond stronger > π
Note: No formal charge formed, hence solvents polarity is not that important
4
Examples of Dienes and Dienophiles
Prefer electron withdrawing groups on dienophile
Prefer electron donating groups on diene
5
Examples of Dienes and Dienophiles
OR>> Employ electron withdrawing groups on dienes and electron donating groups on dienophile
+
100% yield
30o C
OO
HH
200o C
20% yield
+
6
Diels Alder Reaction is VERY Stereospecific!!
7
CO2CH3 H
CO2CH3
H
H H
H
H
H
H H
HExo
Endo
Nomenclature
8
Diels Alder Stereochemistry
Exo Product is usually thermodynamic product but formed slowly
Endo Product is the kinetic product and frequently predominates
9
Diels Alder Stereochemistry
Endo and exo addition require different approach and transition state geometries
Endo Exo
Better secondary overlap of π orbitals for endo>> Kinetic Product
10
Problem from Solomons and Fryhle 13.24 b and f: What diene and dienophile wouldyou employ in a synthesis of the following?
Me
Me
O
O
O
OMe
Me
H
O
OCH3
11
Problem provide a synthetic path for the following:
Starting Material >>>>>>>>>>>>>>> Product
O
12
For “fun/practice” look atS&F 13,16, 18, 19, 24, 25, 28, 40
13
Now for Something New
Chapter 14
Aromatic Compounds and Chemistry
Solomons and Fryhle: 14.1,2,3,10
14
No reaction
Very Slow and requires highPressure
15Solomons and Fryhle, problem 14.16,17
R
16
orthometapara
17
Top Related