Q16P - Organic Chemistry (Mcmurry)

Question

What product would you obtain from a base-catalyzed Michael reaction of 2,4-pentanedione with each of the following α-β unsaturated acceptors?

(a) 2-Cyclohexenone 

(b) Propenenitrile

(c) Ethyl 2-butenoate.

Step-by-Step Solution

Answer

The addition of a nucleophilic enolate ion donor to the β- carbon of an α, β-unsaturated carbonyl acceptor always gives a conjugate addition product and the reaction is catalyzed by a base like $N{a}^{+-}OEt$.

Formation of enolate ion by the attack of a base at acidic α-hydrogen:

Formation of products by Michael addition reaction in the: