Electrophilic attack on conjugated dienes

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Electrophilic attack on conjugated dienes
(-)
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Allyl Cation
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80 20
20 80
More stable it must be!
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Less stable because there is less positive
charge at position 4
More stable since the double bond bears more
substituents
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Cycloaddition reaction (Diels-Alder)
Diene dienophile
adduct
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Diene dienophile
adduct
Either diene or dienophile must have
electron-withdrawing groups while the partner
carries electron-donating groups
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Stereochemistry
1. Always a syn addition
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Stereochemistry
2. The diene reacts in the cis conformation
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