Chapter 21: Ester Enolates

Summary

• We first encountered the Michael addition reaction with aldehyde or ketone enolates when we looked at the reactions of conjugated carbonyl systems with nucleophiles in Chapter 18
• An analogous reaction is possible with other enolates, especially those from active methylene systems.
• Reagents : typically an alkoxide, RO^-
• The first step is the formation of the enolate.
• Active methylene enolates tend to react with α,β-unsaturated ketones via 1,4- or conjugate addition.

• A conjugate addition with a carbanion as the nucleophile is known as the Michael reaction or Michael addition.
• For the mechanism of this type of process, look at the Michael addition of a simple enolate.

• Michael addition of aldehyde or ketone enolates
• Addition of hydrogen halides to conjugated dienes
• Addition of halogens to conjugated dienes

© Dr. Ian Hunt, Department of Chemistry