Enolates of aldehydes or ketones add to the a,b -unsaturated to form 1,5-dicarbonyls.


This reaction is called the Michael addition. Propanone [1] reacts with a,b -unsaturated [2] to form 1,5-dicarbonyl [3]
Michael Addition Mechanism:

Stage 1. Formation of the enolate.



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



Step 3. Acid-base equilibrium



Step 4. Keto-enol tautomerism


{note}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{/nota}