Chemistry Reference
In-Depth Information
resonance, placing the anion adjacent to a carbonyl. Proton transfer migrates this
negative charge to the terminal methyl group.
Following formation of a negative charge at the terminal methyl group, the
terminal methyl group participates in an aldol condensation with one of the
cyclohexanedione carbonyl groups. This aldol condensation involves initial
addition of the anion to the carbonyl followed by subsequent dehydration of the
resulting alkoxide. This dehydration usually occurs under acidic conditions
during isolation of the product and through mechanistic pathways already pre-
sented (consider protonation of a hydroxyl group followed by an E1 elimination
under solvolytic conditions).
3. Explain the following name reactions in mechanistic terms. Show arrow pushing.
a. The ene reaction
Note: Only the hydrogen involved in the reaction is shown.
The ene reaction is an electrocyclic reaction similar to the Diels-Alder reaction and
the Claisen rearrangement. In this reaction, a hydrogen atom is participating in the
electrocyclic process. The mechanism,
illustrated below using arrow pushing,
