Enolates of aldehydes or ketones add to the a,b-unsaturated to form 1,5-dicarbonyls. This reaction is called the Michael addition.


Propanone reacts with a,b-unsaturated to form 1,5-dicarbonyl

Michael Addition Mechanism:

Stage 1. Formation of the enolate.

Stage 2. Nucleophilic attack of the enolate to carbon b of the a,b-unsaturated.

Stage 3. Acid-base balance

Stage 4. Keto-enol tautomerism

The Michael product can condense via an intramolecular aldol, forming an a,b-unsaturated. The set of the Michael addition and the final aldol is known as the Robinson reaction